Pollution Prevention


While the wastewater treatment plant effectively removes organic material from wastewater, it is not designed to remove most chemicals, metals, and small plastics. So, when these items are sent down household drains, they pass through the system untreated and end up in the Napa River and eventually the Bay, where they may threaten sensitive aquatic life.


The best way to protect water quality and the environment is by preventing pollution before it happens. And prevention is a lot easier and less expensive than cleaning up after the fact! So we offer some tips for residents and business owners to help you start taking simple steps towards pollution prevention.

  1. Downspouts & Sump Pumps
  2. Home & Garden
  3. Medications
  4. Pools & Spas

Downspouts & Sump Pumps

Napa gets about 24 inches of rain a year, and most of that falls during short storms with heavy rainfall. To channel that water off of their property quickly, some people connect their downspouts or sump pumps to the sanitary sewer. The problem with this drainage “solution” is that extra rainwater sent to the sanitary sewer during storms can overwhelm the sewage system. The resulting overflows cause raw sewage to run into streets and flow to creeks and the Napa River. This creates a health hazard for humans and wildlife alike. Plus connecting your downspouts or sump pump to the sewer is illegal!


Check to make sure that your downspouts or sump pump are draining to your yard or the gutter, never to the sewer. Some possibilities for keeping rainwater out of the sewer while protecting and enhancing your property are:

  • Connect your downspouts and sump pump to the storm drain.
  • Direct your downspout to a lawn or landscaped area where water can soak into the soil.
  • Direct your downspout to a rain garden (PDF). A rain garden is a shallow depression that collects rainwater and is often planted with native plants. Besides managing runoff on your property, a rain garden can also allow water to percolate into the groundwater and helps to filter out pollutants. See a list of plants (PDF), including natives, that work well in rain gardens.
  • Install a rain barrel under your downspout to capture water for use when it’s dry.

Think your downspout or sump pump might be connected to the sewer, but don’t know how to check? Call us at 707-258-6000 and we’ll come take a look and let you know.

Bay Area Green Business Logo

Shop Green Businesses

Do your part! By choosing Green Businesses you help to protect our environment, because Green Businesses prevent pollution, reduce waste, conserve resources, and reduce greenhouse gas emissions. You can search for Green Businesses in the Bay Area and throughout California on the California Green Business Program website. You can also learn about the Napa County Green Business Program.