How to Select and Install a Quality Boat Bilge Pump

How many hours do you spend on the water? How often do you need to bail out your boat and ensure it runs perfectly? Is your vessel equipped with all the necessary equipment to stay afloat without any worries? If not, a high-quality bilge pump is a critical gear you must invest in.

A boat bilge pump is a lifesaver if water gets into your boat. And it will. Water will find its way to your boat’s bilge through unstoppable rain, waves splashing over the deck or a leaky icebox. A hole in the hull from a collision and improperly sealed ports or hatches can also be the cause of taking in water.

When you leave a lot of water in the bilge, there’s a risk of destabilizing, electrical issues, mold, and corrosive damage.

Here’s where your hardworking boat bilge pump takes control of the situation. It keeps you from the risk of sinking. 

But you can’t pick just any boat bilge pump. There are different types of these, from manual bilge pump to electric bilge pump. You must also consider your boat’s specifications and the water conditions you’ll be sailing in.

A bilge pump that is too small or weak may be unable to keep up with the water flow, while one that is too large may be inefficient and waste energy.

And if your boat has a nasty, prominent hole, don’t turn a blind eye hoping the pump will magically keep things going. It won’t. You must ensure your vessel is always properly sealed and waterproof.

So, let’s break it down and figure out what type of bilge pump you should get.

Types of Marine Bilge Pumps

Not all boats use the same type of bilge pumps. One factor that goes beyond size and capacity is the method used for pumping. Also, each of these has its set of pros and cons. 

If you have enough information about how each one operates and what its strengths and weaknesses are, you’ll be able to make a better choice for your precious vessel. 

Centrifugal Bilge Pumps

A submersible bilge pump is the most common centrifugal pump for small vessels. These pumps use kinetic energy to move water. The pump has a spinning impeller that pushes water into the discharge. It creates low pressure in the pump that sucks more in excess water.

  • High capacity
  • Easy bilge pump maintenance
  • Affordable
  • Can handle small debris
  • Simple design
  • You must prime it before using
  • It won’t get rid of all the water

Diaphragm Bilge Pumps

If you’re looking for an exclusive solution for your small vessel that can run dry, and push and pull water upward without losing power, then a diaphragm bilge pump is the best choice. These pumps use an actuator to expand and contract a flexible diaphragm. This diaphragm creates a vacuum that sucks water into the bilge pump and then pushes it to the exit point.

There are three types of diaphragm bilge pumps you might have to choose between:

  1. Single-Diaphragm – It’s the standard design with one diaphragm running all the action.
  2. Double-Diaphragms – It is more efficient and creates a better water flow.
  3. Manual Diaphragm Pumps – Uses a lever or a crank to create the vacuum.
  • No need for priming
  • It can remove all the water effortlessly
  • You can use it manually
  • You can install it above the boat bilge
  • Not enough capacity
  • Not good with handling debris

Reciprocating Bilge Pumps

Also known as piston bilge pumps, these work well with high-viscosity liquids. So, they’re especially popular with large ships. This pump uses a piston and valve to do the job. When the piston is drawn up, it produces a suction within the pump that pulls water (or air) via the inlet check valve.

And when it’s pressing down, the plunger compels that same water to depart through its corresponding outlet check valve.

  • Self-priming
  • It can remove all the water
  • You can install it over the bilge well
  • Can use it without power (manual pumps)
  • Doesn’t handle debris well
  • Has a low capacity

Factors to Consider When Choosing a Bilge Pump

You don’t want to wait until you’re on the water to decide whether your bilge pump cuts it. That’s why, before you make a purchase, consider these factors:

Type of Boat

The kind of vessel you have will determine the bilge pump you need. Smaller boats require bilge pumps with lower flow rates and capacities. If you have a daysailer, you can use a portable piston pump. For a ski boat, a single submersible electric pump should do well. However, coastal boats might need automatic electric bilge pumps.

Select the Right Size (GPH)

The bilge pump’s size (measured in gallons-per-hour or GPH) is vital. If you install one that’s too small, it won’t be able to handle the bilge’s water flow. And if you choose one that’s too big for your bilge, you’ll waste energy. 

Usually, 800 to 1000 GPH is enough for a mid-sized boat (26′-30′). You can find bilge pumps in many sizes depending on the manufacturer.

Check the Material Quality

Look for bilge pumps made with corrosion-resistant stainless steel or aluminum materials. These materials will help ensure your bilge pump can handle the harsh marine environment and last long.

Check for Noise Levels

When bilge pumps run, they can get quite noisy. You want to make sure the boat bilge pump you choose is quiet enough so it won’t disturb your time on the water. Of course, you’ll have to consider its power output as well. For instance, more powerful pumps will usually be louder than quieter ones.

Power Source

What’s your ideal bilge pump’s power source? You can choose from electric bilge pumps powered by the boat’s batteries or manual bilge pumps. Electric bilge pumps are better for bilges with more water. But if you’re in a situation where your bilge doesn’t need much power, a manual bilge pump is the best choice. And manual bilge pumps will be your lifesaver in emergencies – like losing power in the middle of the sea.

Installing a Bilge Pump

Bilge pump installation easily qualifies as a DIY project. But before you can get your hands dirty and start drilling holes, you must know where to install the boat bilge pumps.

We recommend installing at least two bilge pumps in your bilge. One should be installed near the bilge’s deepest part and the other one a few inches higher.

The one in the belly will take care of small accidents like rain or box drips. Whereas the other one will handle the bigger bilge water flows.

Step-by-Step Guide

Once you’ve picked a suitable pump and decided where you want to place them, follow the steps below for a smooth bilge pump installation process.

1. Install the Strainer

Drill a hole in the bilge, place the strainer, and screw it to secure. The strainer must be at the bottom of the bilge as it’ll handle the debris work.1

2. Connect the Hoses

Now, connect the intake hose to the pump and route it to the strainer. As for the discharge hose, connect it to the pump. Now, route it through the hull to the outside of the boat.

3. Install the Float Switch

A float switch can be put in the bilge. This switch will automatically turn on the pump when the water level is too high. Make sure you put it in a safe place, away from anything that can hurt it.

4. Wire the Pump

Connect the pump to a circuit breaker or fuse panel. It should be connected to the boat’s battery. Put in a fuse or circuit breaker so that there is not too much electricity.

5. Test the Pump

Once the installation is finished, it’s time to ensure the pump runs efficiently. Fill your bilge with water and switch on the pump for a performance test. It will ensure that you get optimum results from your new setup!

Installation Tips

  • Keep the discharge hoses short for better performance
  • Use waterproof butt connectors to prevent your insulation
  • Vent bilge pump to avoid build-up of fumes and pressure
  • Use a smooth bore hose for better capacity and performance

Bilge Pump Maintenance and Troubleshooting

We have good news if you’re new to boats and bilge pumps. These pumps don’t require much maintenance. But you should check for common signs of trouble nonetheless. After all, who wants bilge pump failure on their hands?


  • Clean the pump and strainer to avoid blockage
  • Inspect the hoses for any cracks and damages
  • Replace corroded or worn-out wiring
  • Make sure your battery is charged to power the pump properly


  • Check the bilge strainer for debris if you hear strange noises while bilging. A blocked pump makes a noise
  • If the pump doesn’t turn off, you might have a problem with the wiring or float switch
  • If your pump has a low output, check for blockages
  • If the pump doesn’t activate, check if the bilge water is too low


Installing the right bilge pump properly and maintaining it for long life will keep your time on the water stress-free and smooth. 

So, we recommend you go through the bilge pump installation instructions carefully. Understanding the basics of bilging and maintenance will save you time, money, and effort!