Reducing Phosphorus Pollution to Improve Water Quality

Colorful dishes. Photo courtesy of Brook Beeler, WA Dept. of Ecology.

In the ongoing effort to improve water quality in Washington’s waters, the state is reducing one of the most common causes of pollution: phosphorus in household products.

In Washington State, at least 260 bodies of water are polluted because of nutrients like phosphorus. Phosphorus is a common ingredient in household detergents and fertilizers, where it is often described as “phosphate.” It is used in many industrial processes. Phosphorus also occurs naturally in soil and human and animal wastes.

In water, phosphorus behaves as a fertilizer, accelerating plant and algae growth. When plants and algae die, bacteria consume oxygen that is dissolved in the water. When this happens, less oxygen is available for fish and aquatic life that need oxygen to survive. Excess phosphorus in drinking water is difficult to remove, and also can require an increase in treatment chemicals which adds cost.

Where phosphorus comes from

Industry and wastewater treatment plants account for about half of the phosphorus contributed to Washington waters. The other half comes from a variety of “nonpoint” sources. These sources are hard to trace with no obvious point of discharge, such as stormwater runoff, septic tanks, and agriculture.

Why phosphorus reduction matters

Dishwashing detergent accounts for an estimated 10 to 12 percent of the phosphorus entering municipal wastewater plants. Treatment plants can remove much of the phosphorus in wastewater, but they cannot treat and remove all phosphorous. The phosphorus that treatment plants cannot remove is released into Washington’s waters in treated wastewater.

When we reduce our use of phosphorus-based products we can considerably improve this pollution problem. The best way to protect our state’s water is to avoid putting phosphorus into it to begin with.

There are alternatives to phosphorus-containing detergents that can be just as effective at food removal and spot reduction as phosphorus-containing soaps.

Can't find your favorite phosphorus-free brand at your local store?

Use our printable information cards to let the store manager know that there are environmentally-friendly products available.

Fact:

One pound of phosphorus can grow 700 pounds of algae.

Source: Historical Perspective of the Phosphate Detergent Conflict, Chris Knud-Hansen, 1994.

Last updated June 2008

What the law says about phosphorus*

In 1994: Washington State made it illegal to sell laundry detergents containing more than 0.5% phosphorus by weight and dishwashing detergents containing more than 8.7%.

Beginning July 1, 2008:In Spokane County it will be illegal to sell dishwashing detergent containing 0.5% phosphorus or more by weight.

In Whatcom County it will be illegal to sell dishwashing detergent containing 0.5% phosphorus or more by weight.
Single-use packets, such as tablets or gel packs of detergent, may contain a maximum of 2.0 grams of phosphorus per packet.

In July 2010: The amount of phosphorus allowed statewide will be no more than 0.5%.

* This does not apply to the sale or distribution of detergents for commercial or industrial uses.

For the complete history of the bill and the session law visit the Washington State Legislature website.