Sewage discharge (also known as blackwater) contains pollutants including nutrients, metals, toxins and pathogens. Blackwater discharged from your boat can impair water quality, negatively affect aquatic ecosystems and increase risks to human health.

Did you know? Discharge from a single boat over one weekend contributes the same amount of bacterial pollution as the treated sewage from 10,000 people (California State Water Resources Control Board)!

How does blackwater pollution affect aquatic environments?

The Law

Under federal law, it is illegal to dump raw, untreated sewage into navigable U.S. waters, including coastal waters within 3 miles of shore and inland waters (lakes, reservoirs, rivers, etc.). A No Discharge Zone (NDZ) takes this law a step further and prohibits the discharge of both treated and untreated sewage into a designated body of water.

A NDZ is created if a state determines that a body of water either:

  • Requires greater environmental protection and there are adequate pumpout facilities available.
  • Has particular environmental importance (e.g. sensitive areas such as shellfish beds or coral reefs).
  • Or has drinking water intake zones.

It is important to know the locations of any No Discharge Zones and pumpout stations in the areas where you are boating. The U.S. Environmental Protection Agency (EPA) provides a list of NDZs and pumpout facilities by state.

How to prevent blackwater pollution?

There are several ways to handle waste onboard, including the use of an installed toilet with a Marine Sanitation Device, a portable toilet (porta-potty) or a composting head.

Marine Sanitation Device (MSD)

There are three types of MSDs. The most common MSD for recreational boaters is Type III, which consists of a toilet connected to a holding tank that does not have an overboard discharge pipe and can only be emptied at a pumpout facility. Offshore recreational boats generally use MSD Type I, while MSD Type II are found on large commercial vessels. Both types have the capability to pump treated sewage overboard. All MSDs should be U.S. Coast Guard approved.

Portable Toilets (Porta-potties)

Porta-potties are not considered installed toilets, as they don’t use installed water or power. They must adhere to the regulations prohibiting the disposal of raw sewage within the 3-mile limit.

Composting Toilets

Composting toilets don’t require the use of a holding tank or pumpout facility. They are designed to provide an economical, environmentally safe method of dealing with human waste. Depending on frequency of use, they can be used up to an entire summer season without emptying. The following products are recommended for use on boats and both have a proven track record:

Caribbean Charter Vacations

Many yacht charter destinations do not have pumpout facilities. When you arrive, check with your yacht charter company on the policy. We recommend that if there are no provisions in place, pump your waste overboard while underway in deep water away from beaches and anchorage sites. Pumping out your waste near shore is harmful to swimmers, snorkelers, divers, other water operators, and those who eat the local fish and shellfish. 

Green Boating Guide: