Water Quality > Nonpoint Pollution > Phosphorus Detergent Information

Reducing Phosphorus Pollution to Improve Water Quality

Contents:

• Why it matters
• Where phosphorus comes from
• Why reduce phosphorus in dishwasher detergent
• New dishwasher detergent law as of July 1, 2010
• For more information

---

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.

Why it matters

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 reduce phosphorus in dishwasher detergent

Automatic dishwasher 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.

Back to top of page

Last updated July 2010