Jan 25 2021Share

Only Rain in the Storm Drain

By AMWUA Staff

This weekend we have finally got some much-needed precipitation, and we hope that more will still fall in the Valley to start our week. We tend to go for an extended period without moisture. Yet, when it does rain in Arizona, we know it can often come down quickly and can even cause flooding, creating strong water flows that go over driveways and sidewalks, through streets and parking lots. 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, which is why Phoenix Water Services is focusing on the prevention of stormwater pollution during their 2nd Annual Stormwater Awareness Week. While some debris is easily visible, such as trash items and regular litter, the rain also transports other less visible, more harmful pollutants, like oil and grease, dissolved metals like lead and copper, and unnatural amounts of sediment from oily driveways, constructions sites, and roadways.

It’s also 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 transported through pipes and flows to treatment plants. Whereas storm drains carry water that remains untreated directly into washes, parks, and riverbeds, which then can seep into our aquifers. While both systems have extensive infrastructure, the stormwater system that includes - ditches and culverts, ponds and lakes, curbs, and gutters, is not part of a treatment process point before the stormwater can find its way into our groundwater. This is why we all must do our part to protect our water and our environment by remembering “only rain in the storm drain.”

Basic stormwater runoff facts can help us better understand the impact contaminated rainwater can have on our environment. Here are some valuable tips 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. Just remember to sweep it up immediately and properly dispose of it. 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 because it is more water-efficient. If you choose to wash your vehicle at home, make sure you use a bucket and phosphate-free, biodegradable detergent and direct wash water to landscaping when possible. Make sure you dispose of wash water into a sink or toilet.

Lawn Care
Use pesticides, fertilizers, and other lawn care products sparingly and following label instructions. Overwatering can carry pollutants to rivers and washes. Do not sweep or wash yard debris into the street because it 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 appropriately disposed of or recycled. Take these items to a Household Hazardous Waste site or collection event in your city.

Pools and Spas
Backwash or drain your pool, spa, or water feature to the sanitary sewer using your home’s cleanout. Discharging pool water to the street can contaminate water with chemicals, bacteria, and other pollutants.

Trash & Recycling
Bag and tie up loose trash. Also, make sure you keep trash and recycling bins closed.

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

For over 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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