Storm Sewer vs Sanitary/You Can Do Your Part

Storm Sewer Vs. Sanitary Sewer

Rain, especially Colorado afternoon thunderstorms, causes water to flow down streets. Sometimes, this water flows into a local water body or sometimes it disappears into a drain or pipe. When the water flows into a drain or pipe, some people mistakenly believe that this water is treated. In fact, the water is discharged untreated into a local creek, pond or lake. The mistaken belief that this water is treated results from a misunderstanding between sanitary and storm water systems.

Generally, most indoor water fixtures are connected to the sanitary system. Most outdoor items are connected to the storm water system. A sanitary system captures used water from households and businesses and routes this water to a waste water facility. At the waste water facility, the harmful contaminants are removed and the clean water is released into the environment. Some common every day items that are part of the sanitary system are toilets, kitchen and bathroom faucets, showers and baths.

Storm Water

Unlike a sanitary system, storm water systems only collect storm water and the water is not treated. The collected storm water is transported and released into a local creek, pond, or lake. Some common every day items that are part of storm water system are street drains, culverts, and ditches.


It is important to understand the difference between sanitary and storm water systems because many everyday items such as pet waste, grass clippings, engine oil, or fertilizers accidentally become part of the storm water system. When it rains, water falls to the ground and washes over these pollutants.

These pollutants are then carried by the storm water to local creeks, ponds and lakes, such as Cherry Creek Reservoir. When introduced into the environment, these pollutants, along with other everyday household items, can harm the environment and the people that interact with it.

You Can Do Your Part

Because everyone affects water quality, everyone has a part to play in keeping our water clean. You can do your part by:
  • Maintaining your vehicle so that it does not leak fluids on the ground
  • Properly disposing of pet waste by throwing it away with your trash
  • Following lawn fertilizers, herbicides and pesticides label instructions
  • Not littering
  • Properly disposing of or composting yard waste
  • Participating in the Village’s residential household waste collection program
  • Controlling erosion by encouraging plant growth or ground cover on bare soil
  • Regularly maintaining your septic system, if applicable
  • Never putting any materials into a storm drain or into a ditch
  • Understanding that storm sewers do not treat water