RV Water Pump Problems: Low Pressure, Cycling and Noise

When you are not hooked up to city water, the pump draws water from your fresh tank and pushes it through the lines. A pressure switch on the pump turns it on when you open a tap and shuts it off once the lines are back up to pressure. That on and off behaviour is normal. Once you understand it, the symptoms below are much easier to read.

Many RVs also have an accumulator tank. This is a small pressurized chamber near the pump that smooths out the flow and cuts down how often the pump kicks on. If yours has one and it loses its air charge, the pump will cycle more and the water may pulse at the tap.

Start with the simple things. Make sure the fresh tank actually has water in it and that your house battery is well charged. A low battery slows the pump motor, and weaker flow is often the first sign. A clogged faucet aerator or shower head can also cause low flow at one fixture while the rest of the rig is fine.

Most pumps have an inlet strainer, a small screen on the intake side that catches debris from the tank. If it fills with sediment, the pump struggles to pull water. A loose fitting on the intake side can also let air in, which makes the taps sputter and spit. Look for a cracked strainer bowl or a fitting that is not snug.

In Alberta, one very common cause shows up every spring. If the winterizing bypass valve is still set to the antifreeze position, the pump may draw air or pink fluid instead of fresh water. Check every bypass valve before you assume the pump has failed.

If the pump runs for a second or two every few minutes with everything turned off, water is escaping somewhere and the pump keeps topping the system back up. The cause might be a dripping tap, a toilet valve that does not seal, a loose fitting behind a panel, or a slow drip under the rig. Check cabinets, under the sinks and around the water heater for damp spots.

If you find no water anywhere, the leak may be inside the pump. A worn check valve can let water flow back toward the tank, so the pressure drops and the pump restarts. Hidden leaks are worth chasing quickly, because water sitting inside walls or floors is how soft spots and delamination start.

Rapid cycling while a tap is only partly open is a different thing. Many pumps do this by design at low flow. It is not usually a fault, though a working accumulator tank can make it gentler.

Pumps are never silent, but a loud hum or rattle often comes from the mounting. Rubber isolator feet wear out, mounting screws loosen, and rigid plumbing right at the pump can carry vibration through the floor. A pump that runs but moves no water may be running dry or have an air lock. Running a pump dry for long periods can damage it, so switch it off while you investigate.

If the pump does nothing at all, check the pump switch, the fuse or breaker for the pump circuit, and battery voltage. Freeze damage is also common here. A pump that was not drained or protected before a cold snap can crack its housing, which often shows up as a leak at the pump itself.

Bring it to Horton RV Services in Calgary if you cannot find a leak, if the pump keeps cycling after you have ruled out taps and toilets, if you see water damage, or if the pump has freeze damage or electrical problems. We can test the pump, pressure switch and plumbing, and track down hidden leaks before they turn into floor or wall repairs.