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schoonmakerjon

Fresh water tank replacement

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All, I'm evaluating replacing the RV fresh water tank.  It is the original and ~20yrs old.   The tank's drain fitting has a minor leak, (see pic, lower right) that I've repaired once, sealing with SikaFlex 221, having some success, and not completed fixing.   The tank is ~45"long x 22"tall x 21"deep, and I expect this is ~80gals+.  the standard tanks are available online and YouTube videos illustrate how to insert and seal the fitting outlets.  This tank needs 4 outlets, a drain, water pump connection, fill port and air vent.  I am interested in anyone having taken this DIY approach and understanding the work effort and the reliability of these outlet seals.

Another approach is to go to a plastic "welder" providing the dimensions and port/outlet locations.   I understand these plastic "welder" will then custom build the new tank.  This new tank would basically "pop-in" and I would only need to make the necessary connections, water pump, etc.   Alternatively, I could take the coach to the plastic "welders" and they would build and install.   Again, I'm interested in folks that have taken this custom build approach and your overall cost and success.  Please advise any recommendations/suggestions and overall experience.    Thank you.

water_tank.jpg

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1 hour ago, richard5933 said:

If the tank is in good condition other than the leak, you can have the tank repaired and a new drain fitting installed.

I think that is the way I would go.

Bill

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Bill and Richard,   this is quite helpful.   what groups do these repairs?   Plastic welders?  Tank specialist?   Easily found via an Internet search?   Please let me know any supplier pointers.

Also, I've found some Uniseal products that could fit/seal this opening and these products indicate a reliable seal.   Do you all have any pointers about these Uniseal products?  There are numerous YouTube videos illustrating application/use.    thank you.

 

     ---  Jon

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A Plastic Welder would be where I would be looking. It does take a special torch to do the process. The last time I saw it it was a hot air gun using heated nitrogen with a feeder tube for the plastic rod as a filler material. Kind'a like a Hot Glue Gun.

Seeing your tank, it may have to be removed to do the weld due to space restrictions. However that may have changed since I last saw the process working,

Herman

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You're likely looking for a company that does spin welding. That's what the technique is called that is used to install the new fitting. Who ever does that should also be able to handle other repairs to the tank.

If you can't find a shop by using that term near you, try looking for the nearest plastics supply house. They should be able to direct you to a shop in your area that can do the work.

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8 hours ago, schoonmakerjon said:

Also, I've found some Uniseal products that could fit/seal this opening and these products indicate a reliable seal. 

Not familiar with that product but I bet there are some epoxy products that will work on that type of plastic. I don't know how much it would cost to have a shop do a hot air weld repair but they have guns on Amazon for around $100.00 + https://www.amazon.com/s?k=hot+air+plastic+welder&hvadid=77653062753171&hvbmt=be&hvdev=c&hvqmt=e&tag=mh0b-20&ref=pd_sl_7y3qv1xc3o_e

I would look at you tub and look for videos on how to do it. Then decide if it is something you want to try.

Bill

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Uniseal products are rubber seals which use a tight friction fit. Insert the seal into a hole in the tank, and then a PVC pipe is inserted into the rubber seal. The seal is made by a tight friction fit. Although some have used these as permanent solutions, I'd only use them as a temporary solution, as the rubber is going to harden and shrink over time.

Trying to glue a plastic tank is difficult, especially near the drain or other parts of the tank which are always wet. On the top it is easier to use glue or epoxy since there is no water pushing on the repair, but even then it's difficult to get things to stick permanently to the type of plastic used in most water tanks which is why they use spin welding.

The best solution is to get a new fitting put on with spin welding. Next would be to use a plastic welding gun and some appropriate plastic welding rod to make a repair. I've done this, and while there is a learning curve it's not that difficult for anyone who is used to doing similar things.

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Any competent auto-body shop should be able to plastic-weld the pipe into the tank, IF you can clean all other sealants off the parts. You must know the type plastic of the tank.

Edited by rayin

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30 minutes ago, manholt said:

Richard, I remember when you went thru the learning curve on your tank!  Perhaps you can PM the OP and help out?

Good point. My leak was along a seam line and quite easy to fix. A crack next to a fitting is slightly different, but depending on the severity of it there is still a chance an easy fix would work.

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