The fresh water tank in our previous fifth wheel started filling on it’s own. I noticed water dripping under the trailer and determined it was coming from an over-full fresh water tank. I knew the last time I looked it was near empty and I didn’t fill it. I drained the tank and watched as it refilled over a period of a few days.

The problem was a bad check valve on the water pump. The valve is meant to prevent city water from leaking into the fresh water tank. When this little-known part fails it allows water to flow backward through the pump into the freshwater tank anytime you’re hooked up to city water.

The fix is easy and you can probably do it yourself. Repair the check valve… parts are available at any well-stocked RV parts store… or replace the complete pump if it’s old and you use it a lot.

In my case the fix above wasn’t an option. The water pump was in a place with difficult access. For a water pump we seldom used and which still actually worked, I didn’t want to spend the time and effort needed to get at it. So instead of repairing the pump I put another check valve in the water line at a place I could reach. The pump and the check valve were still working when we sold the rig.

While I’m talking about check valves, the water heater in our new fifth wheel had a check valve go bad. Every time we used the hot water we would hear a buzz. But that’s another tip of the day.

Tips to minimize RV water pump noise.

To minimize RV water pump noise/vibration you should have at least 1 foot of flexible high pressure tubing to both the inlet and outlet ports of the pump. This helps keep the pump’s normal oscillations from being transmitted to the rigid plastic pipes in the RV.

A more expensive way to reduce water pump noise is to replace your old pump with a variable speed pump. While these pumps cost $50 to $75 more the typical water pumps installed in RVs but they dramatically reduce hammer and vibration.

You can also consider installing an accumulator tank. It’s a pressure storage vessel with a bladder inside… air on one side of the bladder and water on the other. Because air can be compressed the accumulator absorbs some of the pump pressure when it pulses making water flow more steady and the pump work more efficiently. The accumulator tank also provides additional water storage to assist the pump in meeting the total demands of the plumbing system.
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The RV Care & Maintenance DVD addresses issues like: information on the proper care and maintenance for the interior of your RV, the exterior of your RV, RV appliances, LP gas system, water system, electrical system, RV generators, RV batteries, chassis & frame and RV tires. Let RV expert Mark Polk, help you to thoroughly understand how to take care of your RV. Watch as many times as you need to.