Human sewage from boats creates environmental and human health problems, affects drinking water quality, recreational activities, reduces oxygen available to aquatic life, excess nutrients cause algal blooms (block sunlight penetration). Vessel sewage is more concentrated than domestic sewage because people on boats use less volumes of water for sanitary purposes than do people on land. A single boat discharging the contents of its holding tank into the waters of a harbor may pose little human health risk. However, if several hundred boats, on the other hand, are docked in a harbor with a poor flushing rate, and they dump their toilet wastes directly overboard, that can present a definite problem.





  • Learn how to use a pumpout by watching this video or check these 10 easy steps

  • Do not want to deal with sewage? If you don't want to service the holding tank yourself, consider using a mobile pumpout service.

  • All boats with installed toilets must have a Coast Guard-approved Marine Sanitation Device (MSD) if operating in U.S. navigational waters.

  • Boats without toilets- use a portable toilet on-board and empty at a dump station.

  • If you have a Y-valve with a through-hull fitting that allows direct overboard discharge, it must be secured in a closed position (using a padlock or non-releasable wire tie) when within the 3-mile limit.

  • Never discharge any sewage, treated or untreated, in a Federally designated “no-discharge area.”

No Discharge Areas in California:

  • Avalon Bay Harbor (Los Angeles County)
  • Dana Point Harbor (Orange County)
  • Lake Tahoe (Placer & El Dorado Counties)
  • Oceanside Harbor (San Diego County)
  • San Diego Bay (San Diego County)
  • Upper & Lower Newport Bay (Orange County)
  • Channel island Harbor (Ventura County)
  • Huntington Harbor (Orange County)
  • Mission Bay (San Diego County)
  • Richardson Bay (Marin County)
  • Sunset Bay (Orange County)

Many chemical disinfectants and deodorizers used in Marine Sanitation Devices (MSDs) contain chemicals of concern including: Chlorine compounds (including sodium hypochlorite), formaldehyde, paraformaldehyde, ammonium compounds, glutaraldehyde, paradichlorobenzene, or anti-microbials (such as Dowicil or Bronopol). It only takes one-tenth of a part per million of chlorine to harm or kill aquatic organisms in the vicinity of a discharge. Use enzyme and bio-active treatments when possible as these are biodegradable and less toxic treatments. Whatever you use, follow instructions carefully and use the recommended amount for treatment.

Trying to solve a smelly problem? Learn more about Green Solutions for Smelly Problems.

  • Empty your holding tank on a regular basis. Full and overfull tanks are difficult and dangerous to drain. Keep a pumpout log on your boat to keep track of your holding tank capacity.

  • Periodically rinse the entire system with water. Connect a hose to the deck fitting for the holding tank and fill the tank with fresh water. Use the pumpout to pump the water out. Repeat if necessary.

  • Clean with a vinegar solution. Before you add any holding tank treatment, use a vinegar solution, about once a month, immediately after a tank has been emptied. This solution will help to reduce scale buildup and it will keep the walls of the hose clean.

  • Deodorize with borax and baking soda To clean and deodorize the boat's head, use a mix of 1/2 cup borax per 1 gallon of water. Clean frequently with a solution of baking soda and water, and sprinkle baking soda around the rim.

  • Change the hoses when needed. Over time, the system hoses, made up of a rubbery material, start absorbing the sewage smell. Perform the following quick test: Wet a rag with hot water and put it around the hoses for a few minutes. Remove the rag and if the rag has a bad odor, like sewage, the odor is permeating through the has and it's time to change it.


Report sewage discharges to California Office of Emergency Response (800) OILS911 (645-7911) and National Response Center (800) 424-8802

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