This is my final solution. I cut an adequate hole in the floor to install a drain plus some extra room, then built a drain into a watering dish and "plumbed" it with some adapters and a garden hose that drains into a utility sink in the basement almost directly below.

Then I drilled the side of the dish, dropped the assembly into/over the hole in the floor, routed the hose to the sink, and inserted a small diameter pipe/hose into the bowl that connects back to our reverse osmosis system. The water flow from that pipe to the dish is gated by a 12 volt DC valve.

To control the valve, I bought a commercial infrared proximity sensor that has an AC outlet on it, plugged the 12 VDC power supply — just a run of the mill linear wall-wart — I use to activate the valve into it, and set the IR sensor for a one minute recycle.

So the way it works is, cat walks up, IR sensor sees them, AC turns on, 12 VDC power supply comes up, valve triggers, fresh water comes out of the pipe, they drink from the arc of water — almost never from the dish — which runs for one minute, and the dish drains immediately.

This way, the water doesn't stand. Doubly important with an R/O system, as there is almost no chlorine left in the R/O water, so the water is less able to sit around in the first place without "things" growing in it.

The system works really well. The pic is right after the install, hence the condition of the floor. I need to catch one of the wee beasties drinking when I have camera in hand. Will post when I do.

#cat

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