7 Steps for Cleaning a Boat’s Bilge

Cleaning the bilge on a boat is about as much fun as changing a dirty diaper. But if your boat is also your baby, better roll up your sleeves and get it done. 


Although cleaning the bilge is far from pleasant, it’ll have less stagnant water, corrosion, mold and foul odors when you do. If you clean the bilge regularly, the task won't be as unpleasant the next time around. Here are some helpful tips for cleaning the bilge on your boat. 

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Bilge Cleaning Step #1 - Get a Biodegradable Bilge Cleaner

Choose biodegradable bilge cleaners, since they don’t leave long-lasting deposits on your boat and won’t harm the ecosystem if you spill any in the water. Although biodegradable bilge cleaners cost a little more than traditional detergents, they’re safe to use around the seats, mats or carpeting in your boat, making them more versatile than a caustic detergent.

Boat bilge cleaning steps

Bilge Cleaning Step #2 - Let the Bilge Cleaner Do Its Thing

Open the boat’s bilge area and apply bilge cleaner to every surface. If necessary, add a small amount of water to the cleaner so it flows into every nook and cranny. Once the bilge cleaner is applied, leave it to fully soak into the dirt and grime for a couple of hours. Always follow the directions on the bottle, but it's likely that the longer you leave the cleaner to penetrate the dirt, the better results you'll get.

Boat bilge cleaning rinse

Bilge Cleaning Step #3 - Get to Scrubbing

After the bilge cleaner has fully soaked into the various stains and accumulated grime, it’s time to get scrubbing. Use nylon brushes, scouring pads, or anything abrasive that gets to all the hard-to-reach places. Although this step is the least pleasant, the more thorough you are with the scrubbing, the easier it’ll be to clean the bilge the next time around.

Boat bilge cleaning steps

Bilge Cleaning Step #4 - Rinse it Off

Rinse the bilge using as little water as possible: the less water, the better. Use enough water to sluice the bilge cleaner and the dirt and debris down to the bottom of the bilge.

Boat bilge cleaning wash

Bilge Cleaning Step #5 - Carefully Dispose of the Bilge Water

There will likely be traces of oil in the dirty bilge cleaner/rinse water. However, keep in mind that it’s a federal offense to discharge oil into the water surrounding a boat. The violation carries a hefty 5-figure fine, so you’ll have to carefully remove the bilge water from the boat using a sponge and a bucket. Once the bilge is dry, dispose of the rinse water at a waste facility that accepts oil-contaminated water. It’s also illegal to dump oil into the public sewer system, so don’t pour the dirty bilge cleaner/rinse water down a drain.

Boat bilge cleaning waste disposal

Bilge Cleaning Step #6 - Clean Up Oil Spills

If you spill any oil into the surrounding water, clean it up immediately. Use an oil spill kit or absorbent pads to remove the oil from the water. The legal limit for polluting water with oil is 15 parts per million, which is about half a teaspoon per 50 gallons. The Federal fine for oil pollution as of this writing is $10,000, so even the smallest spill must be dealt with. Don’t use detergents on oil pollution in the water because the detergent just spreads the oil wider, and the fine for doing so is more than double the fine for the spill. 

Boat bilge cleaning steps oil cleanup

Bilge Cleaning Step #7 - Prevent the Bilge from Getting Dirty

It’s impossible to keep your bilge completely clean all the time, but you can minimize the amount of oil and chemicals that get into it. Regularly service your engine to minimize the possibility of oil leaks; make sure all hose clamps are tight; inspect hoses for leaks; ensure there’s a drip pan under the engine; keep oil-absorbent pads on board; and clean up any oil or fuel spills immediately. Finally, stay on top of bilge pump maintenance

Following these tips should help keep the grueling task of cleaning a dirty bilge increasingly manageable each time, and also keep you out of trouble with the law.