Actually, the first impression was that the Aqua Hot on the opposite side of the coach was dripping; but, good detective work and a drop light led me back to the true source: the Manabloc manifold.
I'll spare you all the trials of rebuilding the manifold, replacing connectors, etc. and skip to the end: someone had not properly winterized the rig, and there are tiny cracks from freezing in the top of the stack.
To the rescue came Louise Stout at Viega, who now owns the Manabloc name. She can be reached at 800-976-9819 Ext 220 and is one of those rare treasures we in the RV community love to have working on our side.
Foremost, she told me that creativity on my part to undo the damage done by RV technicians' cross-threading the cold water supply line would parallel their own level of poor methods: it turns out that the threads atop Manabloc manifolds are NOT the standard plumbing variety, that they are a proprietary pitch. She referred me to Pex Supply equpping me with a part number (46414) for the correct 1" female connector that joins up to 3/4" Pex.
Then, she looked up my manifold model number in their computer, pronounced it a rarity no longer in production -- heck, my RV is only a 2007 model -- and put in a work order for their shop to custom-build me its replacement. For $140, I get a new manifold and all outlet connections.
Checking the plumbing manifold should be part of your monthly inspection routine.
Open up the plumbing bay and inspect the floor for water. If power has been off the rig, rusty hardware might be the sole indication of leakage.
Check under the rig for signs of long term leakage. Painted garage floors will have a telltale halo that indicates a leak/evaporation cycle.
Touch the top of the manifold to ensure the recessed aren't harboring water.
Check outlet fittings for security and leakage.
Inspect manifold hardware for signs of moisture, eg rust.