Keep your water pressure under control


By Greg Illes

RV water systems are designed for modest water pressures. The typical built-in 12-volt pump produces a maximum of 45 psi or 55 psi, which is enough for a decent shower. But when you hook up to “city water” there are no guarantees.

I’ve been connected to water supplies as low as 18 psi (wow, does that take a LONG time to fill the fresh tank), and as high as 125 psi, which is enough to damage water system components. It’s always a Russian-roulette game, and it’s one you really don’t want to play.

The short story is to always test the water hookup before you hook up. But this involves digging out your water-pressure gauge (now which drawer was that in?), screwing it onto the faucet, testing, unscrewing, and then (finally) attaching your water hose. For most of us, it kind of begs for laziness (“Oh, it’s probably okay”), which can be an expensive mistake. A handier solution is to make up a water quick-connect assembly with integral gauge.

Here’s all you need, available from any local hardware store:
•Water pressure gauge
•Water manifold Y-fitting with shut-off valves
•Short flex-line “hose-saver”

The Y-fitting female attaches to the flex-line and then to the city-water faucet — the flex line allows attaching the setup to even the most inaccessible faucet. The water-pressure gauge attaches to one of the Y-fitting male outlets and your water-hose to the other.

When you are ready to hook up screw the flex line onto the city-water faucet, turn off the valve going to the hose, turn on the valve going to the gauge, and then turn on the city-water valve. The gauge will show you what pressure you have. If it’s okay, turn on the Y-fitting hose valve. If the pressure is too high, of course you’ll need a regulator — but you don’t need to employ such a flow-restricting device if the water pressure is under 80 psi.

Leave the whole setup attached to your water hose and you’ll never get lazy. This dandy apparatus will keep you honest, always providing the important pressure reading whenever you connect your precious RV water system to that strange faucet.

Greg Illes is a retired systems engineer who loves thinking up RV upgrades and modifications. When he’s not working on his motorhome, he’s traveling in it. You can follow his blog at

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