Aug 05 2019Share

Only Rain Should Go Down the Storm Drain

By Warren Tenney

With monsoon season now upon us, we eagerly await the arrival of much-needed rain which will add moisture to our yards, refresh the air, and minimize dust. However, monsoon season can also bring heavy rainfalls that create strong water flows that go over driveways and sidewalks, through streets and parking lots increasing the chance of flooding. These forceful water flows can also carry pollutants such as trash, oil, pet waste, and pesticides into our storm drains contaminating water that eventually flows into our local washes, parks, streams and wetlands.

Stormwater runoff is one of the leading causes of water pollution in the United States. While some of the debris is easily visible like trash items and regular litter, the rain also transports other pollutants which are not as visible but far more harmful, like oil and grease, dissolved metals like lead and copper, and unnatural amounts of sediment from oily driveways, constructions sites, and roadways.

Storm drain vs sewer drain graphicIt’s important to note that not all water is treated equally. The cities have two separate water collection systems. The sanitary sewer system collects wastewater from sinks, toilets, showers and washing machines that is transported through pipes and flows to treatment plants. Whereas storm drains carry water that remains untreated, directly into washes, parks and rivers. While both systems have extensive infrastructure, the stormwater system that includes everything from ditches and culverts, ponds and lakes, curbs and gutters, to wetlands and rain gardens, are not part of a treatment process at any point. This is why it is vital that we all do our part to protect our water and our environment by remembering “only rain in the storm drain.”

Basic stormwater run-off facts can help us better understand the impact contaminated rainwater can have on our environment. In addition, there are valuable tips the cities provide their residents to help us all better understand the role we can play in keeping our stormwater free of contaminants including the following:

Pet waste
Collect pet waste in a plastic bag and throw it away in a garbage can. Pet waste contains bacteria and other pathogens that are not healthy additives to our water.

Automobile Maintenance
Properly maintain vehicles to prevent fluid leaks. Use drip pans to catch leaks. Clean up leaks and spills using an absorbent such as kitty litter or sand. Sweep up immediately and properly dispose. One quart of motor oil can contaminate over 250,000 gallons of water.

Vehicle Washing
Use a commercial or self-service car wash if possible – it is actually more water efficient. If you do choose to wash your vehicle at home, make sure you use a bucket and phosphate-free, biodegradable detergent. Direct wash water to landscaping, when possible. Dispose of wash water into a sink or toilet.

Lawn Care
Use pesticides, fertilizers and other lawn care products sparingly and in accordance with label instructions. Over watering can carry pollutants to rivers and washes. Do not sweep or wash yard debris into the street. Debris can clog storm drain inlets causing flooding.

Household Chemicals
Keep chemicals in labeled, closed containers. Unused household chemicals, including paint, used oil, cleaners, and yard chemicals should be properly disposed or recycled. Take these items to a Household Hazardous Waste site or collection event.

Spill Management
Keep absorbents, such as kitty litter, sand or old rags on hand for cleaning up spills. Absorb spills and immediately sweep into a trash bag and dispose in the garbage.

Pools and Spas
Backwash or drain your pool, spa, or water feature to the sanitary sewer using your home’s cleanout. Or backwash the water to your yard, making sure the water stays on your property. Discharging pool water to the street can contaminate water with chemicals, bacteria and other pollutants.

Trash & Recycling
Bag and tie loose trash. Keep trash and recycling bins closed.

The practice of these healthy household habits by all of us can keep common pollutants off the ground and out of our stormwater. In the end, clean runoff is a community effort that begins long before it rains.

For 50 years, Arizona Municipal Water Users Association has worked to protect our member cities’ ability to provide assured, safe and sustainable water supplies to their communities. For more water information visit

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