Noisy water pumps are a very common complaint among RV owners. Some RV manufacturers use the cheapest pumps and installation methods to reduce cost, but this often results in “water hammer,” chattering pipes and floor vibration.
There are simple, low-cost steps you can take to quiet your system.
A typical water pump will be secured by four screws. Remove the screws and slip a rubber mouse pad under the pump. Re-secure the pump, being careful to not over-tighten the screws. Using a mouse pad will help to isolate the pump vibrations from the floor.
Locate rattling water pipes. Turn on the pump. Have a friend open and close any faucet while you try and locate where the rattling noise is coming from. Typical areas are where the cold water pipe passes through or runs along a cabinet wall. In this case, the cabinet acts like a sounding board and increases the noise.
Wrap the pipe where it rattles against the cabinet or flooring, with 1/2-inch foam insulation. It should slip right over and not require any securing to the pipe, but a little duct tape on each end of the insulation wouldn't hurt. Repeat this step until you have insulated all rattling pipes.
Sometimes water pumps can rapid cycle on and off rapidly (in less than 2 seconds) during low flow conditions. This can cause pulsations in the water system and create noise. To determine if adjustment is necessary, turn a faucet on to a lower than average flow of water. The pump should cycle, but its off time should be 2 seconds or longer. If the cycling is correct, no adjustment is necessary. If the pump is cycling rapidly, increase the setting by turning the adjustment screw on the pump clockwise (one turn maximum) until the pump operates with at least 2 seconds of off time.