mikev

Water Filtration and Reverse Osmosis

23 posts in this topic

Hello, I am looking to put a water filtration system on my coach. I just saw a system at Costco. It was a Watts Premier 4 stage "RO" (Reverse Osmosis) system. Has anyone had any experience with RO systems in a MH? I have been cleaning and treating my freshwater tank regularly but am somewhat shy about using the water for drinking without a good filtration system, our city water is fine but you are never quite sure of a RV resorts water.... I plan to plumb in something that would filter both incoming city-resort water and my fresh water tank water.

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First, if you have a clean fresh water system there is no reason not to drink the water. We use a sediment filter and a secondary carbon filter on all incoming water so the tank is as clean as any water source you can find.

Second, assuming you are only wanting to use the RO for your drinking water be aware that most RO systems discard 2 gallons of water for every gallon of water they produce. If you dry camp much you are going to lose a lot of usable water to the RO process or dump "dirty" water from the RO back into your fresh water tank. I suppose if you plan to head for Mexico you would need something like that (or bottled water) to ensure a good fresh water supply, but otherwise it is likely over-kill. If you want a "fresher" water supply for drinking water I would suggest that you simply install a separate drinking water filer with a separate output. Several versions are available. We have "water-through-the-door" on our refrigerator and this supplies water to the ice maker as well. I have a separate filter on this line which filters "everything" from this line only. I have clean ice and bottled water quality drinking water. I buy one bottle of water every 6 months or so and reuse that one bottle over an over with this water source.

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WARNING! WARNING! Wil Robins. You do not want to use a carbon filter for filling your fresh water tank. If you use a carbon filter you remove clorine from the water going into your fresh water storage. Clorine keeps your water free for Bacteria and Algee. You can become quit ill from that water if it sits for any length of time in your tank. Your are much safer putting your filter inline after the tank and fresh water inlet and the pump. Then you are filtering only the water just before you use. There was a hotel in Florida that filtered it water through the whole system and 1 guest died and several became ill. (sorry for any missed spelled words)

Most city water is fine for your tanks then it can be filtered for taste and smell just before you use.

Happy RVing

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Warning or no warning, we have been doing just that for the last 10 years and it works great for us! Sometimes my wife says "you're sick", but I don't think that's what she is talking about. We don't keep water in our tanks for very long since we full-time, but I guess we also have the same charcoal filtered water in our tanks all of the time since every drop in goes through the filters.

Now, the question becomes how long are the filters really filtering (did I change them often enough) how well are they actually filtering (did I buy the cheap stuff) and how much could they filter in the first place (I think you can figure that one out).

I use, and will continue to use, a sediment filter followed by a charcoal filter, before I allow any water into my fresh water holding tanks. I then use a super fine filter from the tank to my drinking water/ice maker connection but I often drink water right from the tap (GASP!).

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Warning or no warning, we have been doing just that for the last 10 years and it works great for us! Sometimes my wife says "you're sick", but I don't think that's what she is talking about. We don't keep water in our tanks for very long since we full-time, but I guess we also have the same charcoal filtered water in our tanks all of the time since every drop in goes through the filters.

Now, the question becomes how long are the filters really filtering (did I change them often enough) how well are they actually filtering (did I buy the cheap stuff) and how much could they filter in the first place (I think you can figure that one out).

I use, and will continue to use, a sediment filter followed by a charcoal filter, before I allow any water into my fresh water holding tanks. I then use a super fine filter from the tank to my drinking water/ice maker connection but I often drink water right from the tap (GASP!).

Bill I mean you no disrespect. However if you will look in the FMCA Forum under "Water and Holding Tanks", "Mold in fresh water hose", there are several comments about mold. As of today my reply of Decemder 14, 2009 is the last post in that topic and you may see where I quoted a Fox News.com report.

I wish only good health to you and your wife.

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No disrespect taken. I can tell you, however, that I recently pulled my 165 gallon fresh water tank (20 years old) and replaced it with a new one due to fatigue failures. There was not any sign of anything out of the ordinary. It was the exact same clean "plastic" as the tank I replaced it with so I am not sure what possible health problems might have been created by the way I load and use water in my tanks. I really doubt that any of the carbon filters sold at Camping World or the RV water filter dealers do such a good job as to remove all chlorine and I doubt that there are many (if any) users who are faithful enough to replace these filters after filling their tanks with 2000 gallons (or as stated) of water, so even if the filters worked perfectly for the first month or 2 their abilities would be greatly diminished by the time someone got around to installing a new one.

Now, if you put on a new filter, fill your tanks and then let them sit for the entire Winter season your results might be different than those that I have found as a full-timer.

Additionally, over the last 10 years, I have added bleach to my fresh water tank twice, driven around for a good sloshing, flushed much of this water through all of the known water lines and then drained it all out. I doubt that made any real difference, but I did do that for the 2nd time about 5 years ago.

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Like Bill I use a charcoal filter and have for 6 years with no ill effects and no mold or algae in my fresh water tank. I have left the water in the tank for as long as a month or so although if I am not using it from the tank I usually dump it every two to three weeks.

We lived in NH for 18 years and had a well with with no chlorine and stored water in five gallon containers in case the power went out. I kept them for over six months with no visible signs of anything growing in them.

As a kid growing up in West Texas we got our water from a cistern that was filled with water that ran off the roof. No chlorine and no problems. We probably developed immunity to the bacteria involved.

Maybe I still have it (immunity) because we drink the water from the tap everywhere we go. I might be somewhat more careful in MX though.

Obviously there can be pathogens in water and reasonable care should be taken but I think the obsession with water that has developed in the last 20 years or so has little basis in fact.

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Hello,

I just installed the Costco Watts reverse osmosis system about a month ago in our motorhome and it works great. I send the drain water back into the main water tank since it is not all that polluted anyway and that water is only used for washing dishes, laundry, showers, etc. The super clean reverse osmosis water is sent to the refrigerator to make ice cubes, cold water for drinking and it is also sent to the insta-hot faucet for making hot drinks with super clean water.

I add some bleach to the main water tank normally to kill any bacteria that may come from adding water during our travels.

A sediment whole coach filter is in-line right after the main water enters the coach before the main tank.

The charcoal filter ( an additional one, because the unit from Watts also has one), is before going into the regfrigerator.

I have installed Culligan systems and Watts systems before in differing applications, and the new one offered at Costco is about the easiest one I have ever installed. I do not use the faucet that comes with the unit, and I have to purchase additional fittings to route the system where I desire it to go, but the end usage of this system is wonderful.

We have sediment reduced, bacteria treated, and reverse osmosis treated water all from a single, simple system.

You will need at least 40psi for the system to work effectively.

Hope this helps and encourages.

Thank you,

Tim Sparks

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Hello,

I just installed the Costco Watts reverse osmosis system about a month ago in our motorhome and it works great. I send the drain water back into the main water tank since it is not all that polluted anyway and that water is only used for washing dishes, laundry, showers, etc. The super clean reverse osmosis water is sent to the refrigerator to make ice cubes, cold water for drinking and it is also sent to the insta-hot faucet for making hot drinks with super clean water.

I add some bleach to the main water tank normally to kill any bacteria that may come from adding water during our travels.

A sediment whole coach filter is in-line right after the main water enters the coach before the main tank.

The charcoal filter ( an additional one, because the unit from Watts also has one), is before going into the regfrigerator.

I have installed Culligan systems and Watts systems before in differing applications, and the new one offered at Costco is about the easiest one I have ever installed. I do not use the faucet that comes with the unit, and I have to purchase additional fittings to route the system where I desire it to go, but the end usage of this system is wonderful.

We have sediment reduced, bacteria treated, and reverse osmosis treated water all from a single, simple system.

You will need at least 40psi for the system to work effectively.

Hope this helps and encourages.

Thank you,

Tim Sparks

Hello Tim, how do you deal with water from a shore connection, does it go through the Watts system too. I spoke to a Watts technician and he said that the rejected water is generally cleaner since it has been cleaned by the multiple filters, it just has a higher value of "pollutants" after the RO membrane as it is sent back to the main tank. However the cycling of water, replacement/replenishment from the fresh water tank on an ongoing basis will naturally deal with the issue. Also as the water is brought back through the RO system it is fully cleaned once again. I was thinking of plumbing in the system and having two sets of valves, one to pump water from our fresh water tank with the discharge water returning to the tank, and the other having the externally connected water go through the RO system and then the discharge go to the holding tanks. How did you deal with the external water connection?

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Hello Tim, how do you deal with water from a shore connection, does it go through the Watts system too. I spoke to a Watts technician and he said that the rejected water is generally cleaner since it has been cleaned by the multiple filters, it just has a higher value of "pollutants" after the RO membrane as it is sent back to the main tank. However the cycling of water, replacement/replenishment from the fresh water tank on an ongoing basis will naturally deal with the issue. Also as the water is brought back through the RO system it is fully cleaned once again. I was thinking of plumbing in the system and having two sets of valves, one to pump water from our fresh water tank with the discharge water returning to the tank, and the other having the externally connected water go through the RO system and then the discharge go to the holding tanks. How did you deal with the external water connection?

Yes, the shore connection is also treated by the Watts before human consumption. I put the Watts module under the sink in the galley. I tied it into the connection that was already present for the Insta-hot, then took another line over to the refrigerator with another "T" connector. My normal sink water is not R/O treated, so it would come straight from the tank or the city connection.

I hope this explains my set up better.

Tim

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I don't see what the problem is. I have an external 3 filter system that then goes through a RO membrane and into the main tank. The whole coach is on RO - no more water stains and we always have good drinking water wherever we go. I drain the tank and let it dry out when we get home. It is also great for washing my coach as my house water has an extreme amount of minerals and leaves water stains.

Just my 2 cents worth.

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Mike:

I have the exact Watts system you are looking at installed in my motorhome. I put it in about 6 Mos.ago and am very pleased with it. There are several things to consider. RO systems do not like hard water as it cuts the membrane life short. I am sitting at my ranch in Nevada and the water is terrible so I installed a water softner in a shed and run the water through it before it reaches my motorhome. This way I have soft water for the motorhome and RO water for drinking and the ice maker. The info that RO systems use about 2 or 3 times more water than they produce is true. This does not create any problems while hooked up to sewer, but is a problem if on your tanks. In talking to Watts about this problem their tech suggested that I run the RO waste water back into the white tank as it is not contaminated in any way and can be used. This keeps from loosing this water when dry camping. It would be necessary to put a valve into the system so you ran your water out into septic when hooked up to city water. I have not done this yet but plan on pursuing this before we go back to full timing. DO NOT WASTE YOUR MONEY on a Permeate pump which supposedly would reduce the water wasted. I tried one and it just does not work in a motorhome and I almost burnt up my water pump. You will have to change to a higher pressure water pump as you need to have at least 40 - 80 lbs at the RO.

The install went really easy and if you want to call me I will tell you what little I know.

Jack H. Davis- 775-315-0280

2002 Bounder 39z

2007 Trailblazer

3 Yrs 8 Mos till we can go back to fulltiming!!

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Whole house RO? With a 165 gallon fresh water tank it would take running almost 500 gallons through the RO to fill the tank and the Home Depot version says it produces 11 gallons PER DAY. We also full-time so there is no such thing as letting things dry out when we get home. I am pleased to hear that is works for you but it is not a terribly practical solution for most RVers. I would be replacing filters faster then I could buy them

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FOLKS! An RO system, first of all needs at least 60 PSI to work properly, you must have also a one gallon reservoir and the RO itself. This will take a great deal of space and yes it will waste 1 gallon of water for each gallon it produces.-- If you are dry camping this will not be the way to filter water -- unless you have a 60 PSI water pump and at least 4 batteries just to fill the one gallon tank -- yes it will drain your batteries since it will keep the pump going for a very long time until it makes the one gallon it requires for the system to stop.--- The best small filter I know so far is the PUR filter I use it at the faucet.

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After getting a bad tank of water, I installed 2 water filters and a reverse osmosis system in the Fleetwood Discovery. It has worked extrememly well. The quality of the water is consistent, the water feels like silk and ice cubes are clear. My system first filters the water through a micron filter, then carbon before going into the RO. I fill my water tank and draw water via the water pump. This way I also get consitant water pressure. I purchased my unit from "Your Water Source". Ken and Paula can be reached at 206-369-7724.

Steve Masterson

Blue Sky Ranch

F272580

rvtraveler100@Yahoo.com

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I installed an RO unit in my 2003 Newmar Dutch Star 40’ as one of the very first modifications. We have had an RO unit in our home for years and not knowing what the quality of water is at the various RV parks we’d be staying in, not to mention the potential for bacterial, viral and who knows what other contamination in the fresh water holding tank I considered the installation of an RO unit to be essential.

I installed a Watts “Zero Water Loss†system under the kitchen sink with a separate faucet for RO only. We have a “whole house†cartridge type filter for all incoming water and I didn’t feel it was necessary to use RO water for anything other than what we drink or cook with (i.e. not shower, sinks or toilet).

The Watts “Zero Water Loss†system incorporates a pump which, in a household situation is designed to pump the excess water that would normally go into the sewer, into the hot water line, thus eliminating the loss of approximately 5 gallons for every gallon of RO water produced by the RO system. At the time I thought that the pump would be necessary in order to pump the excess water back into the fresh water holding tank, but in retrospect I found that this is not necessary. A standard RO system will work just fine.

The first summer that we used this system I discovered that by having the excess water return to the fresh water holding tank we would have a problem with the fresh water tank overflowing when we were hooked up to the water supply in an RV park for an extended period of time. This could be remedied by periodically turning off the incoming water and using the water in the holding tank (which, of course required running the motorhome’s water pump). After the first summer I installed a valve under the sink and ran a second line to the sink drain pipe which allowed me to select either sending the excess water to the fresh water tank or to the gray water tank depending on whether we were in an RV park or dry camping. I also installed a switch to turn off the RO pump if, for whatever reason, I didn’t want to be producing RO water (such as if the fresh water tank were to run dry while dry camping). This switch, of course, would not be necessary with the standard RO system (i.e. one other than the Watts “Zero Water Loss†system).

We have been very happy with this system, as have our friends in whose coach I installed a similar system, and have felt much more confident about the quality of the water we are ingesting as we’ve traveled in 44 states and 9 provinces.

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I've had whole house RO in my coach for 5 years, and it is the nicest thing we have added bar none. My wife loves it; never spots in the shower, faucets don't corrode, drink from any faucet any time; I can pull a bucket of rinse water for the coach or windows that will dry streak and spot free. I did the installation which was fairly easy if you have some plumbing schematics or can figure out your coach's plumbing routing. We camp in the southwest where the water is rank (>800 ppm Total Dissolved Solids), and in Mexico where it is of questionable purity and also high in TDS, and have zero issues wherever we fill up, except for what to do w/the reject water (more on that below). Got my setup from Vagabondwater.com; there are other great dealers for water products as well. Service is pretty important because each configuration has at least some variables. For whole house RO, the fill rate of your tank in an RV setting will be central to finding a good system. It will be hard to get satisfactory fill rates from any of the small membranes, regardless of manufacturer claims; I want to fill my tank and don't want to take 12 hours to do it (tho I can fill overnight the day before unplugging if I remember) because sometimes you decide you need to head out and didn't think ahead. I also have a semi-automatic control, pushing a button to start the fill cycle, with a float switch in the tank to shut it off; a latching relay opens & closes the input valving as needed to start/stop the fill cycle. If I'm boondocking for a while, I bypass the semi-auto system w/a manual valve & watch to see I've got the last 5 gallons in the tank for good measure.

Under-sink type RO is another good alternative, but you don't get benefits all around the coach. Definitely send reject water back to the main tank if you are going to do this. I've heard some send the reject to the sewer, which is nuts.

A couple of posts mention a minimum input pressure. Mine can fill from city pressure or I can valve over to a booster pump. I could literally fill my tank from 5 gallon buckets if needed using the booster. I have filled from city pressure down to 25psi, which is slow slow slow, but it works. North of 60 is better. My booster sends input pressure to over 100. Higher pressure runs the RO membrane both faster on thru-put, and higher in pollutant removal (I'm getting north of 97% removal of dissolved junk in the water always, 98%+ using the booster so 800 parts per million dissolved pollutants becomes less than 16ppm). I have a "comparitor gauge" that shows ppm on input water & output, so water quality is easy to check any time w/push of a button.

Reject water from a single membrane is variable w/my system which is fairly deluxe (I dial in the desired reject %). Generically RO systems use a 1:3 ratio w/1 gallon product water to 3 gallons of input, so 2 gallons reject water. When I had a one-membrane system, I used 1:3 (33% product water) if I had a use for the reject water, and 1:2 (50-50 product to reject) if I was sending the reject water down the sewer. I have since added a second membrane which takes its feed from the first membrane's reject water. Now it is 3 in and 1.67 to the tank, 1.33 to the sewer or plant watering as applies. On our lot in AZ, I water the plants w/the reject water, which they love (our palm trees are bigger than the neighbor's which only get bubbler water when the timer waters plants. In Mexico where water is much more dear, I dial the reject rate to 50% so I get 2.25 gallons product from 3 gallons input (0.75 gallons reject).

RO membranes degrade w/time, hardness of input water, reject % and some other input variables. If you use the standard 1:3 product to input ratio, you are washing the membrane surface at the optimal rate. Lower reject rates will trap stuff in the membrane surface and cause it to degrade faster. My membranes are 2.5"x20" or so (way larger than the under-sink type) and should last about 5 years under RV use. Like tires I expect them to die from age rather than gallonage limits. I could pre-treat for hardness while in AZ, like one post above, but because the membrane life wouldn't be affected much, I'll just send local water thru the membrane & replace as needed. Membranes are not cheap, but if they die from old age then I'm getting my best monetary efficiency out of them anyway. Under sink type membranes (and filters) come in various canister designs. FWIW I'd stay away from the proprietary designs; mfgr's change designs over time and once your replacement type is no longer available, you have to replace the system or do an interesting replumbing project rather than a drop-in replacement. Push-type PEX fitting canisters will likely be around, while proprietary spin-on types likely will change. Not that it isn't a good system, it is, but the GE Merlin setup (google) is one of those expensive element types that I expect won't be around in 5 years or will have an incompatible successor. I'd rather replace cartridges (i.e. just the membrane and filter elements) in standard config's, even if the housings cost a bit more to start. The push-type-PEX canisters are pre-fab w/housing and element inside, but have been around for some time already, so you can probably switch brands if your original supplier goes out of business. I see a lot of sleek looking proprietary canisters recently, and don't think they will be a bargain over time. Don't buy extra membranes, as they may be degraded by the time you want to swap.

As to filters, here are some suggestions.

1) two-stage filtration is a good compromise for RV'ing. First a sediment filter, and second a carbon block filter. 2.5" x 10" canisters make a good setup, can be plumbed together and inline from your hose connection so all city or all tank fill water gets filtered. Canisters also make a perfect system disinfection point- remove the cartridge media, add chlorine to the canister, spin it back on, then fill your tank; rinse and you are good to go. No more pouring chlorine down a hose and spilling it on yourself or clothes (or at least less spillage for the less adept). My canisters are permanently mounted in the basement for convenience. Don't buy clear housings for an exterior or lit location which will grow algae from the sunlight; opaque is better.

2) Sediment filters: these are inexpensive to change, and should be changed every 6 months regardless of use. Stuff grows on the media as it gets trapped there and a year old filter will get kind of interesting (which is bad for your water, tho good for a grandkid who wants to learn biology and has a microscope available). Sediment filters are rated by micron level of junk removal. 5 micron is the max I'd suggest. I'm now trying some 0.5 micron cartridges which remove most cyst-type bacteria (bacteria like giardia and cryptosporidium roll into a ball and form a hard cyst shell that is impervious to chlorine, and they are very small, i.e. will pass a 1 micron filter). The cyst type bacteria are the worst and most treatment resistant germs. 0.5 micron will also trap some viruses, tho most viruses are very very small, and hopefully killed by chlorine in city water, or filtered out by soil in well water served RV parks. I use depth-wound string filter elements for sediment, but thick spun polypropylene are good also. Pleated paper filters are ridiculous; there just isn't enough media to trap much for long. Sediment elements are so cheap that going a little bit cheaper is a fools errand IMO. 5, 1 and 0.5 micron elements are easy to find and cheap to buy.

3) Carbon filters: You will find granular carbon, and carbon block filter elements. For an RV I would not recommend any element that doesn't say carbon-BLOCK. The "block" part means the carbon was crushed and reconstituted to a block that your water must pass thru. Water can pass between and around granules of carbon and get zero filtering from it. Another, and significant issue IMO is the initial cleaning required for granular carbon- you will see some black carbon in the initial 5 or so gallons passing thru a granular carbon filter as it gets its final wash, and this carbon goes right into your system (plumbing or tank). Block type elements have little or no wash-out carbon. Usually the finer micron granular elements have more wash-out carbon, but quality of construction is a bigger variable, i.e. cheap granular filters will wash out a lot. Carbon is very aggressive in adsorbing chlorine. The carbon block element I use has 120 acres of pore surface area (that's correct, 120 acres in a 2.5x10 element) to grab chlorine and other stuff. As stated above, if you have a really good carbon-block element, you will have effectively zero chlorine in your tank. Over 5 years I had for a short while a moldy taste to the water out of one tap in the coach. Finally I used a cup of high-chlorine water (added 2 tblspn's bleach) to immerse the strainer end of the faucet, and that killed the mold and it hasn't come back. The moldy taste only happened when we didn't use the coach for a month or more, and went away after a day's use regardless. Never had a problem w/the tank, and have never disinfected the tank; I drain it when it will set for a long period. 10, 5 and 1 micron carbon block filter elements are readily available and run $15-25 each. I recommend changing them every year. Again, over time a carbon block element will trap stuff that grows on it, so yearly or less is important regardless of gallonage run thru it. For aggressive filtration- 0.5 micron sediment, then 1 micron carbon-block. I don't see much advantage to filter costs above 5 micron sediment/10 micron carbon-block. If an element doesn't say carbon-block, it is granular.

If you want some additional reading, get The Drinking Water Book by Colin Ingram (less than $20 delivered from Amazon IIRC). The subject matter is distilled for a lay reader (i.e. don't need water chemistry or sophisticated plumbing background), quite thorough, and pretty interesting for folks like us who travel around and get water from multiple sources. I was the engineer for a local water district for a while. Sorry for the long post; hope it is useful. Mike

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Mike,

Welcome to the FMCA Forum.

Thanks for the EXCELLENT and nicely detailed post.

Brett

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Overall a very good summation article by engineermike. Thanks Mike.

I spent many years as the owner of a water purification company designing and building RO systems commercially. We only sold larger commercial RO's so I don't have much specific info on small 50-75gpd RO's other than the theory is the same for all sizes of RO's. The biggest problem with water filtration and purification advise is that there is not one solution for everyone as water is different everywhere you travel. Many towns have 2 or 3 different water sources so what works on one end of town does not necessarily work at the other end of town. The advice I have given in my professional life was that there is no "one size fits all" solution.

Returning waste RO water to the water tank without monitoring as Mike does is not a great idea in the long haul as for every gallon of water produced the waste water contains twice the mineral (dissolved salt) concentration and an inefficient small RO can become useless pretty quickly as the membranes will become plugged, especially with hard water. Can be done but should be monitored as Mike does.

Removing chlorine can be a dangerous practice without applying very regular sanitization cycles. The best example I can use is to fill a bucket of water. Let it stand around for a few days and then feel the insides of the bucket below the waterline. The bucket will be slimy. This slime is commonly called biofilm. If bacteria are introduced into a biofilm rich environment the bacteria count will quiet literally explode, as it is like they have an endless buffet of food. While many may have no problems with this practice, you do so at your own risk. As one member mentioned earlier in the posts, people can become very sick and die if something goes wrong. But many people never have a problem.

You also need to factor in that many RV parks have people practicing unsanitary water connections. One neighbour in a park in Vegas told me he had the perfect water inlet system coupled to his sewer flush-out. What this amounted to was a simple "Y" connection. One side to fresh water inlet and the other to sewer flush out. No backflow prevention. He said prior to switching to using purified water purchased in bottles they always had upset stomachs. No guess as to why that was. Residual (free) chlorine levels remaining in city water are not sufficient to deal with raw sewage being injected downstream from chlorine injection sites. You may not be doing something like this, but your neighbour just might.

It also must be considered that not all bacteria, moulds, algae, etc are killed by chlorine as Mike indicated. Chlorine does not kill everything and in most cases just prevents growth while maintained with chlorine. Remove the chlorine and the growth is resumed. I have had many cases over the years, where once chlorine was removed prior to RO membranes, the algae bloomed and the pipes were completely green as the algae grows back very fast as the food provided by the algae that did die, provides the food source. A good practice is to try and eliminate light, food and warmth to maintain low bacteria counts. Mike's suggestion to use darker filter housings versus clear ones is a good one. Most RV's are typically located in warmer environments and this is a reason to be more cautious than cavalier with sanitization as bacteria log counts can go from a count of less than 10 to millions within 24 hours under the right conditions.

You may not choose to use RO, UV or ceramic filters but to presume all is well because you can't taste or smell anything wrong is no guarantee for success. You can't taste the bugs that give you the flu either.

I personally use small micron filtration for our entire RV coupled with water softener and monitored UV sterilization. We travel in US, Canada and Mexico full time and drink the water everywhere we go.

For what its worth, our worst water found to date, was not in Mexico, but in Swan Lake at the north end of Vernon, BC Canada. Filters were useless after one week of use. The water was full of sediment as well as tannins (stained surface water) and is under a 12 month boil water advisory by the health department for these reasons. The people staying in the park were unaware that they should not have been drinking the water. No notices were published (required by law) in the area or by the RV park who were aware of the problem.

Hope this helps.

Adrian Thompson

The Water Guy

adrian@writeslice.com

www.writeslice.com

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Adrian- I think we've pushed the envelope on this thread, for the better. Coupla thoughts.

I run whole house RO for my rig (not an under-sink unit), i.e. the storage tank on board is filled thru two stage filtration, then RO treatment. All water in the coach is RO water, and I run off the house pump all the time (I have a spare pump installed & ready to plumb over, and have used it once when the main pump failed). My reject water goes to the plants or to the sewer depending on best available recipient. Your admonishments about never chlorinating are good food for thought. I will rethink a regular tank & interior plumbing chlorination, even though as you note it may be I'd never have an issue. After all, chlorination is a small chore, takes maybe a relaxed hour every year or so. Good safety practice.

As to under-sink RO units: if an RV owner is using 5 gallons out of 100 for drinking, or even 10, then the increased TDS in the holding tank shouldn't be an issue. My thinking is the tank gets filled every two to five days depending on occupant habits. So there is a periodic but regular inflow of fresh water used for showers, washing dishes, etc. that will keep the TDS to a manageable level. The only exception to this would be if somebody got on the 3 gallon per day, "sailor's rations" sort of usage for extended boondocking (i.e no refill for long periods). The TDS in the holding tank could get pretty high by the end of a ten day camping stint w/no fresh input, and the under sink unit recycling the tank contents around and around. However, the remedy I'd recommend is to take bottled water for drinking and shut off/bypass the under sink unit for extended boondocking. Whole house RO does not suffer this problem, as all water on board is good water and there is no further treatment while camping.

A point you raised about small membrane systems is exactly why I chose to go with the larger whole house setup. Tiny membranes are good for maybe 1-2 years given conditions RV'ers present, but if you park where hardness is bad (like most of the southwest where snowbirds flock for winter, and the water tastes foul), you may be getting RO water from a small membrane within maybe 6 months that isn't really well treated. Hardness can ruin a small membrane proportionately faster than a large one. Good reason to monitor in/out quality of RO water. Also a good reason to rethink the membrane size. If you really park for extended times where water is severely hard, pre-treating w/ion-exchange softening is a consideration, but cost of that versus early retirement of a larger membrane will present cost trade-offs. Softening also requires carrying extra equipment, and recharging the resin media, which accepting a somewhat shorter life on a larger membrane omits. And of course the common misconception that softening alone takes stuff out of water needs to be dispelled; i.e. softening exchanges one kind of stuff in the water for a different, call it preferred, kind of stuff. For my money, I'd rather just take the extra stuff out all together, which requires RO or distillation, and RO is way easier and more turn-key.

Which brings the conversation to membrane sizing versus membrane rating. I have two membranes, rated at 300 gallons per day at 107 psi. Broken down to hourly, that's 12.5 gallons IF you run it at 107psi. To fill my 100 gallon tank from empty would take 8 hours at that elevated pressure, longer with lower input pressure. I've seen really small membranes stacked in pairs w/a "rated" capacity of 300GPD, but that rated flow comes at about 220psi, which the sellers don't bother to state; the real make rate is way, way lower than even 12 gallons per hour under normal conditions, maybe as low as 2 or 3GPH. In addition to the fallacious water make rating, the small size (about comparable to under-sink units which actually make only a handful of gallons per day) is subject to the hardness and other fouling we discussed above. but getting back to make rate, at 60psi, a good park pressure, you will still take nearly a full day to fill your 100 gallon tank from empty. This takes a lot of pre-planning. When I ran a 300GPD membrane at 25 psi, and 3 people taking showers in the coach each day, I needed about 16 hours of recovery time to make sure we had reserve (sometimes the water gets shut off), but that was just staying even w/3 people in the coach! If I'd had one of the 300GPD @ 220psi systems, it would not have kept up, period. Going to the so called "low pressure" 107psi rated membrane, I can make a full 100 gallons in most parks overnight without the booster pump; using the booster I can fill the tank in less than 4 hours. Now for folks that fill w/straight or filtered city water, that will take an adjustment as you are probably filling in less than an hour. But the difference in water is fabulous if the local source isn't good to start, so I gladly make the sacrifice in pre-planning water intake. If I'm partially full, and decide to pull up stakes, I start making water w/the booster pump then go about my chores to break camp (put away chairs, BBQ, mats, etc. In about an hour I've added up to 30 gallons which for us is good for 3 days if we watch consumption even a little. As you can see, lifestyle involves water use rate, and options for fill time. But with a reasonably sized RO system the shift isn't too big.

I see you picked up on the clear filter canister problem. I see rigs w/a see-though, hose-connected canister filter sitting in direct sunlight outside the coach all the time. If I walk thru a park w/100 spaces, I'll probably see 5 of them, along w/opaque canister setups at another 10 or 15. All that warmth has to be good for something that wants to grow. Adding sunlight makes it a slam dunk that algae and other stuff will bloom.

I never thought when I got into RV'ing that water would be such an interesting topic. Mike

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I agree we have really maxed this thread and I hope some have found it helpful. A few final thoughts for all.

RO can be a great alternative based on your situation. I always like try and bring balance to these discussions as we have the camps of no filtration right through the spectrum to RO. RO is not the panacea some might think.

RO water is typically my first choice as toxins, pesticides, medications, etc are largely removed as well. But RO can be problematic in certain water conditions such as algae laden water systems, tannins, colloidal clay situations. We must remember that RO is still just a very small pore size, filter media and like any filter the right combination of things can kill a membrane (filter) in days to weeks. Many people think magic happens, but all an RO does is provide what is essentially a self cleaning filter. Cross-flow filter I think is a good way to describe it. As water passes through the membrane a cross-flow of water serves to flush the membrane waste down the drain. Hence 1 gallon filtered and 1 gallon to wash the contaminants down the drain.

Because we travel so much and experience so many varying water types, I find filtration and UV an easy safe alternative for our needs. When we return home we drink RO water from one of our 3 retail water locations.

I agree RO really is great for washing the car as it is spot free.

One thing we have not covered is the fact that RO should never be used on microbiologically unsafe water alone, without either something like UV before or after the membranes. UV after the membranes is simplest. There are a couple of reasons for this:

1. Some strains of bacteria can grow through a membrane to the "safe" side and then the membrane is useless and must be discarded. The RO must then receive a full detergent wash and then a sanitization prior to new membranes being installed.

2. Membranes are not guaranteed as microbiologically safe from any membrane manufacturer. If you ever get to watch membranes being made you would never rely on RO alone for safe water. There can and often are some pin holes in the membrane material used for making the entire membrane assembly that you see in your RO unit. The assemblers try and look for these holes on a light board. When they see them they place a circle of glue around the membranes to seal the hole. But some holes may be missed. Assembly is by no means a perfect process. Some membranes are assembled by hand and others by machines.

3. Not replacing carbon filters regularly is a big problem and is the number one cause of membrane failure. If you do not change the carbon filters before chlorine breaks through them a membrane can be damaged very quickly. The reason is that chlorine breaks down the glue they use to make the membrane envelopes and bad water passes to the good water side rendering the membrane unsafe and useless. This is another reason to monitor the in and out TDS levels like Mike does so that you can see if this occurs.

Pressure is an important factor in RO membrane life. Low pressure equals low water velocity of flow across the membranes. The velocity of this water flow is what cleans a membrane. Low flow = short life invariable. Higher pressure membranes typically also deliver better filtration characteristics for chemical and atomic bonding reasons of the salts being filtered. But that is for another discussion forum.

I have placed some articles as I find time on my website at www.writeslice.com. It has links to filtration charts showing different filter media and what micron size is required for filtering different things out of the water. Some might find this an easy chart to understand the place for each filtration type. The Water Filtration section is by no means comprehensive, as I just work on it for fun and to try and help people understand water filtration. If anyone has specific questions feel free to ask away from the website and it sometimes spurs me to write new articles for others to see.

The link to the water section of the site is: http://writeslice.com/water-filtration

Cheers and happy trails.

Adrian Thompson

The Water Guy

adrian@writeslice.com

www.writeslice.com

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Hello, I am looking to put a water filtration system on my coach. I just saw a system at Costco. It was a Watts Premier 4 stage "RO" (Reverse Osmosis) system. Has anyone had any experience with RO systems in a MH? I have been cleaning and treating my freshwater tank regularly but am somewhat shy about using the water for drinking without a good filtration system, our city water is fine but you are never quite sure of a RV resorts water.... I plan to plumb in something that would filter both incoming city-resort water and my fresh water tank water.

There is a company coming out with a new certified water technology that will process any water into bottled water quality for the whole RV or boat.

The system will also allow you to use it in MEXICO and drink the water like bottled water.

It is small and portable it is easily located outside the RV or boat where you connect the hose to the "IN" and a hose to the "OUT" to the RV or boat.

I'm told it will be at Camping World later this summer.

SOUNDS LIKE IT'S WORTH WAITING FOR.

Ciao

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