How to Install a Washdown Pump 

The simplest way to clean fish guts, weeds, dirt and other debris brought aboard your boat is by having a washdown pump installed and ready to go.  

A washdown pump system is exactly what it sounds like: a water supply and a pump. The pump draws in external seawater (or raw water) via a thru-hull and pumps it up above deck, where a hose is connected to clean off your boat after every use. You don’t need much to install a washdown system. If you already have a seawater (or raw water) line in your boat, you can use it to feed the washdown pump, so all you’ll need besides the pump itself is the hoses and clamps to install it.

If your boat doesn’t have a seawater line, you’ll need to install a thru-hull, seacock and strainer to supply your washdown system, as well as the washdown pump itself.

Which Washdown Pump Should I Get?

Get a washdown pump powerful enough to raise the water from the point it enters the boat to the point it exits the hose while maintaining a respectable pressure. 

A washdown pump’s performance is measured in its capacity to pump gallons per minute. The higher a pump’s capacity, the more water pressure it generates. Get a washdown pump that meets capacity requirements based on the size of your boat. For example, a 3GPM washdown pump will be capable of producing up to 50PSI, which should be more than adequate for a typical small-to-mid-sized boat.

The other important consideration when choosing a washdown pump is where it’ll be installed. So if a particular pump is too large to fit the allotted housing, you’ll either have to choose a smaller alternative or a different location to mount it. 

Installing a Washdown Pump

Step 1. Choose an accessible location to install the pump, keeping the length of plumbing pipes and electrical wires to a minimum. Most pumps need to be installed in areas that stay dry.

Step 2. Mount the pump to a sturdy part of the boat such as a bulkhead, using a rubber insulator between the pump and the boat to reduce vibration and noise passing from the pump to the boat. 

Step 3. For a boat with an existing seawater line, add a T-connector or Y-connector into that line to supply the washdown pump without having to install another thru-hull. If there’s no existing seawater line, install a new thru-hull fitting complete with a seacock shut-off valve to supply the washdown pump.

PRO TIP: Don’t use the inboard’s raw-water intake line, as the washdown pump may steal too much of the motor’s cooling water. Only use a marine-grade hose with a higher PSI rating than the washdown pump’s capability. 

Step 4. If the washdown pump is below deck, install a washdown outlet plate through the deck, and run the pump’s outlet hose to the underside of the outlet plate.

You can attach a regular hose and spray nozzle to the topside of the outlet plate whenever you need to clean your boat. If the washdown pump is in a storage locker, connect a coiled hose to the pump’s outlet hose and keep it stowed in the locker until it’s needed. 

PRO TIP: Install an accumulator tank after the pump’s outlet and check valve to reduce water pressure spikes from the pump. Fewer spikes means a longer lifespan and less battery power needed to power the pump.

Step 5. Use marine-grade wire that is the correct gauge for the amps your washdown pump draws. Add marine-grade crimp-on butt connectors with heat-shrink tubing for all connections. 

Run the pump’s electrical circuit to and from your boat’s electrical distribution panel, and make sure the circuit has its own fuse or breaker.

If your boat doesn't have an electrical distribution panel, run the pump’s electrical circuit directly to and from the battery, with an inline fuse close to the battery terminal in the positive wire. Install a waterproof on and off switch for the washdown pump.

Additional Washdown Pump Installation Tips

Add an inline strainer or filter between the thru-hull and the washdown pump’s inlet to prevent debris from damaging the pump. If you had to install a new thru-hull to feed the pump, add a new strainer too. Make sure there’s a check valve at the washdown pump’s outlet to stop any backflow into the pump, if it doesn’t already come with a built-in check valve.

With a washdown pump system installed, you can now supply water to just about anywhere on your boat. You could plumb the pump’s outlet to supply anything from a shower to a fish descaling and cleaning area. And you can use it to hose off the anchor or even your dog! Whatever you put it to use for, a boat washdown pump is definitely worth the investment.