the water pump was orignally under the sink. In order to achieve one drain line (one of my Airstreams has four--one pair in the front and one pair in the back--didn't want to do that again), I had to locate it back near the water heater. A big plus is that there was room to do so and open up the sink cabinet even further.
I made a module to support the pump and accumulator, that could go in and out as one piece. It also put the accumulator fill port in an accessible location (more on the modified cabinet, but weeks from now, I'm sure). I tested it for leaks before I installed it (it's a semi-pain to get at the screws that secure it to the floor).
One lesson learned here. The crimp tool requires almost 180 degrees of clear space out from the connector. I had failed to note how wide the tool opens and almost couldn't get the last crimp done to install the pump module. This could have been avoided with a little better planning.
In the under-basin detail above, you can see that it was tight getting everything installed and tight, but I can actually get a wrench on every fitting. The yellow wires wrapped around the red pipe were to the switch for the exhaust fan.
Note that the blue line to the water heater has a valve in it. Not a requirement, but I have found that there are times when I'm boondocking that I don't want to take 6 gallons to fill it up. Conversely, there are times when I want to drain the pipes (from my copper days), but don't want to drain the water heater (I'm a firm believe in mass--the fresh water tank and water heater are big enough that it would take a lot to freeze them. Not so, a pipe.) This valve would normally be open all the time.
Bad news. On first test of the system, the valve to the water heater leaks! Not onto the floor, but it doesn't do its job. Crap, bad place (tight) to have to remove and replace. If you have any way to test your valves before putting them in, I highly recommend it. This is a ball valve, which are usually very reliable, but not this time. I'd guess I've experienced a 7-10% leakage of this type in all types that I've purchased, so checking them is a good idea if you can figure out a fixture that will allow it.
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