Owning a swimming pool or spa can be a great way to enjoy the outdoors, but draining or maintaining them improperly can harm our creeks, watersheds, and ocean. Pool and spa water often contain chlorine, bromine, copper, silver, algaecides, and other chemicals that are extremely toxic to aquatic life. For perspective, chlorine levels about 0.01 ppm can harm fish and wildlife, yet most pools are maintained at 2-4 ppm, hundreds of times higher. With a few simple steps, you can help protect the fish, insects, and other critters that depend on clean water.

Where should pool and spa water go?

The preferred method is to discharge dechlorinated water onto a landscaped area. Plants and soil act as natural filters and help prevent from reaching storm drains and creeks. This option works well as long as:

• The water is fully dechlorinated or debrominated (use extra caution with bromine as it is extremely persistent)
• The pH is between 6.5 and 8.5
• The land area is large enough to prevent erosion or runoff into gutters or storm drains

If landscaping isn’t an option, the next best choice is the sanitary sewer system. Contact your local sanitary district first to make sure the discharge won’t cause problems downstream.

Discharging to the storm drain should only happen when all other options are not possible, and only when:

• The water is completely dechlorinated/debrominated
• Copper and silver concentrations are safe for aquatic life
• The pH is between 6.5 and 8.5
• The water is free of unusual color, dirt, suds, or algae
• No filter media or acid cleaning waste is discharged
• The water has cooled to ambient temperature

How to Dechlorinate Pool Water

Dechlorination takes time, so plan ahead.

• Natural dechlorination:

Sunlight will gradually reduce chlorine levels as long as no new chlorine is added. Remove chlorine sources from the pool and filtration systems and allow about four days of sunshine before testing and draining.

• Chemical dechlorination:

Check with your pool supply store or maintenance professional for options such as sodium thiosulfate. Read instructions carefully. Determine your pool’s volume and current chlorine level to calculate the correct dose. For example, a 20,000-gallon pool with 2 ppm chlorine requires 450 grams of dechlorinator. Mix the product in a bucket of warm water and distribute it evenly throughout the pool. Allow the water to cycle through the filtration system twice before re-testing and draining.

Disposing of Filter Rinsewater and Backwash

Filter rinsewater and backwash contain concentrated pollutants and must never be discharged to streets, storm drains, or creeks.

• Rinse cartridge filters onto a dirt area and mix the residue into the soil
• Backwash sand and diatomaceous earth (DE) filters onto a dirt or rocked area
• Keep all backwash discharges out of the street and storm drain
• Temporary wash areas must fully contain all washwater. If washwater reaches gutters, creeks, or storm drains, the area is inadequate.
• If you do not have a suitable dirt area, contact your wastewater treatment authority on discharging to the sanitary sewer (Pretreatment may be required to remove DE and prevent sewer blockages). A permit is required.

General Pool and Spa Maintenance Tips

• Clean your pool or spa regularly and maintain proper chlorine levels, filtration, and circulation
• Manage pH and water hardness to reduce copper pipe corrosion, which can stain your pool and harm creeks
• Try less-toxic alternatives before using cooper algaecides. Only use copper if other methods fail
• Dispose of unwanted pool chemicals properly. Many are considered hazardous waste! Visit the Less is More website for hazardous waste disposal information.

For more great tips to help prevent storm drain pollution and protect creeks and the ocean, check out our Homeowner’s Guide in English and Spanish.