As usual, we sometimes get into comparing apples and oranges, with the occasional red herring thrown in to get our eye off the ball. In this case, the apples and oranges are boat vs. and home water systems. Also, pressure switch/accumulator vs. computer controlled VSD based boat systems. The red herring I accidentally threw in was the voltage/current issue which had several listees focusing on the wiring- gauge and integrity. This was never the problem. I expected the 5.7 vsd pump to act like a household system; turn it on and bam, pressure. For example, as you crank open the galley faucet, the pump speed ratchets up to meet the flow demand. However short a period, opening the valve completely takes a bit of time. But, when the Tecma toilet flushes, the solenoid snaps open almost instantaneously, opening a 1/2" hole in the system causing a huge pressure drop. I tried paralleling my 4.5 and my 5.7 VSD's. I'm convinced the flow rates are not additive; I didn't get 10 gpm. The paralleled pumps still can't handle the faucet/toilet trick but they can almost handle the two faucet scenario. Almost. Oh, and by the way all these DC pumps have 1/2" NPT fittings, restricting inlet and outlet flow rates. I started researching 120 VAC shallow well pumps and came across the fact that the normal household flow rate is 8-12 gpm at 40-60 psi. That's why I could never see the water pressure I wanted. Sears has a 1/2 HP pump that will supply this flow and pressure for $150. With pressure gauge, bladder accumulator, etc. I can put the system online for <$200 in not much more space than my current 12vdc system. I have a full time inverter so the 120 VAC isn't a problem. Now, what to do with $500 worth of DC pumps? Regards. Larry