Bilge Maintenance

The bilge is the lowest internal part of your boat’s hull, where water collects, along with spilt and leaked fuel, oil, antifreeze and other toxic liquids. Any accidental discharge of oil is both illegal and detrimental to the ocean as it is toxic to marine plants and animals. A single quart of oil (4 cups) can create a two-acre oil slick! Conducting regular bilge inspections and quickly addressing any required maintenance will prevent oils from sneaking into the ocean. 

Bilge maintenance tips:

  • Check for unusual growth, unpleasant odor and mildew.
  • Check limber holes (drain holes through the frame of a boat) are clear to ensure water and other liquids can pass freely.
  • Keep your engine tuned. Check for any leaks and drips.
  • Secure an oil-absorbent pad under your engine and an absorbent bilge sock next to (but not interfering with) your bilge pump.
  • Keep oil and fuel-saturated absorbents away from heat or sources of ignition in well-ventilated areas.
  • Discard used oil pads and bilge socks according to state and local regulations.
  • Consider installing an oil/water separator.
  • If there is too much oil for a bilge sock to absorb, remove oily water at a bilge pumpout station.
  • Do not use dish soaps to make a spill disappear. It causes the oil to break down into tiny particles, which if pumped out, make the spill much harder to contain and clean up. Dish soap is also highly toxic to marine life.

Recommended products:

Duke Marine Lab in North Carolina and BoatU.S. Foundation conducted independent testing of 21 bilge pads. They found that many of the products sold were not effective and some were highly toxic. The 3 products below were the most efficient and had low toxicity levels:


The Environmental Protection Agency (EPA) defines bioremediation as a “treatment that uses naturally occurring organisms to break down hazardous substances into less toxic or non-toxic substances.” In short: oil-eating bacteria ingest the oil, turning it into a harmless substance. For these bacteria to work in your bilge, they need a small amount of water at 40°F minimum, and several weeks or months to work. This is good as a long-term oil treatment, but ineffective in short-term or accidental spill situations. NavalKleen Small Craft Formula is designed for use by recreational boaters.

Green Boating Guide: