Sewers and storm drains: Are they two separate systems?

Updated October 14, 2019
Sewers and storm drains: Are they two separate systems?

Do you know the difference between the sewer system in your home and the storm drain system located on your street? If the answer is no, you’re not alone.

  • Water that goes down sinks, flushed down toilets or used to wash dishes and laundry flows through the plumbing in your home and connects into your neighborhood sewer pipes below ground. It eventually travels to a wastewater treatment plant, where it is treated to remove pollutants before the water is sent back to the environment or used to irrigate golf courses, street medians and parks in certain areas in Roseville.

  • Water that flows onto streets and into gutters goes into storm drain pipes that flow directly to local creeks. This water flow is called urban runoff. On the way to the creeks, urban runoff picks up pollutants left by cars, people and pets, and eventually ends up – untreated – in our creeks and rivers.

That runoff is called stormwater pollution. We don’t always see the major effects of stormwater pollution because it’s often out of sight and a cumulative problem. Every pollutant, no matter how small, combines with others to harm aquatic life and affect overall water quality.

Many everyday activities contribute to stormwater pollution. However, there are many ways that you can help lessen impacts to the environment.

To learn more of how to reduce effects to our creeks and rivers, visit