The best way to understand a water pump is by imagining what RVing would be like without one. An onboard water pump is designed to move water through the plumbing pipes when the RV is not connected to city water. Which means that without a functioning water pump, any time you would want to shower, drink a glass of water, cook, replenish the icemaker, wash dishes, flush the latrine, water plants or clean the sand from your feet at the outside shower, you would first have to hook up the RV to a city water outlet or operate a hand pump.

Fortunately, you do have an onboard water pump, and for all the convenience the pump provides by delivering water straight to the faucet, this component requires only two things to function – electrical power and fresh water. Power to operate the water pump is supplied by the house batteries. If you know the batteries are charged but the water pump does not turn on, check the battery cut off switch and the fuse located in the house fuse panel. Water needed to operate the water pump is pulled from the fresh water holding tank. Never attempt to run the water pump without ample water supplies and risk damaging the pump.

The water pump is an on-demand component. Turn the pump off when not in use to avoid excess cycling that can damage the pump. If the water pump ‘short cycles’ when all the faucets are off, this usually indicates air in the lines.

A screen is installed between the water pump and fresh water tank to filter debris. Buildup on the inlet screen can cause valves inside the pump to jam. Inspecting the screen and removing particulates should be added to your routine maintenance schedule. Prior to cleaning the screen, disconnect battery power and turn off the incoming water supply.

When all faucets on the RV are closed, static pressure is generally 75-85 PSI once the pump cycles off. With one open faucet, operating pressure runs around 65 PSI and the water pump will run at normal speed. If another faucet is opened at the same time, water pump speed will increase.

The Aquajet water pump is known as a variable speed pump that uses a circuit board to limit the pump according to current by the outlet pressure and flow. A drop of 15-20 PSI when one water faucet opens is considered normal. Adjustments to the water pump motor should only be made by an authorized service center upon pre-approval of the water pump manufacturer to prevent voiding the component warranty. Adequate ventilation around the pump is required to offset high temperatures generated by the water pump when in operation. Do not insulate the water pump in an attempt to lessen noise or prevent freezing and risk damaging the pump. If the water pump seems to be making an unusual amount of noise, it may be time to replace the pump.

Multiplex systems are designed by programming each switch with the address of a particular channel module. In the case of the water pump, the module is ‘F’ and the channel is 7. When the water pump switch is pressed, a command is sent to the multiplex controller to activate channel 7 of the F module. Module F receives this command, engages channel 7, and sends a command back to the multiplex controller that channel 7 is active. The multiplex controller then sends a signal to the switch to turn on the indicator light. The activity in the module depends on the type of module. A latching module latches or unlatches an

Without a functioning water pump, any time you would want to shower, drink a glass of water, cook, replenish the icemaker, wash dishes, flush the latrine, water plants or clean the sand from your feet at the outside shower, you would first have to hook up the RV to a city water outlet or operate a hand pump.

internal relay. A FET module uses Pulse Width Modulation (PWM) to control duration of the power applied to the load. PWM quickly switches power on and off. The faster PWM operates, the brighter the light. The process occurs so quickly we can’t see the actual power pulse, but only that the brightness in the light is changing due to the inability of the filament in the bulb to fully energize. The control module may have a dipswitch setting. Changing this module requires coinciding the current dipswitch setting. Absence of the LED light in the multiplex switch may indicate a blown fuse.

Winterizing the water pump is necessary to protect the system against freezing outdoor temperatures. If you winterize the RV using antifreeze, turn on the pump once the solution has been introduced into the system and run the pump long enough to move antifreeze into the pump. Winterizing the RV by blowing air through the lines to remove water will require that you remove all water from the pump and disconnect the inlet and outlet fittings until it is time to put the water pump back in service.

RVers who prefer remote camping locations often carry a back-up water pump to avoid interrupting their dry camping plans if problems arise with the current component. Check with your service representative to obtain the proper replacement. Model numbers may differ. If you are interested in upgrading the water pump, first take a close look at the power requirements to be sure your vehicle systems are adequately sized to handle the increased load.

We all appreciate the freedom of enjoying the RV away from shore power services, not only while camping, but also as we drive along down the road. The water pump helps provide us with that independence, and with proper care and maintenance, you can rely on water at the faucets no matter where your travels may lead.