Eco-Tip for 8/25/19
Swimming Pool Maintenance
By David Laak and David Goldstein, Ventura County Public Works Agency
As summer fades into fall, swimming pools may be used less, but as any pool owner knows, pool maintenance season is year-round. Covering a pool every night is the best measure to conserve energy, reduce evaporation, and limit chemical use, but pool maintenance raises the biggest one-time environmental issues when pool owners consider draining.
Although some pools are drained on a schedule, pool maintenance experts have differing opinions about water replacement. Many experts agree draining is necessary only for repairs requiring water-free access or to address problems with total dissolved solids. Even super cleaning can be accomplished without draining; you can instead shock the water with a treatment, followed by vacuuming and filtration.
If you do drain your pool, check with your local public works department for permitting requirements. Draining of a pool or spa to the street, curb or storm drain system may violate the Ventura County National Pollutant Discharge Elimination System (NPDES) Municipal Separate Sewer permit unless certain conditions are met. Anything in the storm drain system does not get treated, so it can travel directly to local creeks, rivers and the ocean.
Some local jurisdictions may allow draining into the sanitary sewer but check with your sewer/wastewater service provider to determine if this is allowed in your area. If allowed, pump the water into a sewer cleanout or sewer connection, being careful to prevent flooding.
If your jurisdiction allows you to discharge into the storm drain system, including the street curb and gutter, the following actions must be taken to avoid violation of Ventura County’s permit:
o Reduce the chlorine level to a maximum of 0.1 parts per million (ppm) and the pH reading to 7-8 prior to draining. This can be done by aeration, holding time, and/or the use of sodium thiosulfate.
o Ensure the water is clear of algae and mosquitoes before draining.
o Check to see the drainage path is clear so as not to pick up dirt, lawn clippings or other debris.
o A pool that has been neglected and filled with leaves and debris may need specialized filtration.
o Do not drain your pool to a septic system.
Special consideration is required for drainage of a saltwater pool or spa. In some cities it is illegal to drain saltwater into either the storm drain or the sanitary sewer system, and you may be required to haul the water for disposal via truck. Contact your local public works department for permitting requirements and prohibitions.
Take special care to prevent illegally releasing pool chemicals into the environment. Avoid overuse by reading the manufacturer directions before using any pool chemical.
If you are the owner of a fiberglass pool, take special care to maintain a proper pH level (7.4-7.6). Excess acid in a fiberglass pool results in low pH conditions that can strip copper from heating coils or copper pipes, causing copper pollution. If your pH is lower than 7.2, there is a risk of this corrosive environment in the water. Also, for control of algae, use a hypochlorite shock treatment rather than copper-based algaecides. Release of pool water with high levels of copper to the storm drain system harms aquatic life.
When performing pool or spa filter maintenance, a common practice is to backwash the filter. With backwashing, used filter media and trapped dirt or contaminants are flushed out of the diatomaceous earth (DE) pool filter under pressure. Backwash water contains the same chemical properties of your pool water, plus all the “stuff’ that your filter has removed from your swimming pool. This material may not be disposed in the street, gutter or storm drain system and instead should be bagged wet and disposed in the trash. In some cases, pool filters may have a PVC pipe causing the backwash to flow to a drain that discharges to the street or gutter. If your pool filter backwash has the potential to discharge to the street, installing a DE separation tank can prevent the release of harmful pollutants to the storm drain system. According to the Resource Center at the Poolcenter.com website, a DE separation tank can collect used DE while allowing pool water to return to the pool. The used media, along with the filtered particles, will be caught in a tank allowing you to discard the waste into a trash can. The downside to separation tanks is they need to be emptied after backwashing, and they tend to create back pressure, reducing backwashing effectiveness.
Commercial pools are required to install a properly sized separation tank on the backwash line to any D.E. filter. The separation tank will collect the D.E., so it is not discharged with the backwash water. New commercial pools are also required to have an approved connection to a wastewater discharge system, according to Ashley Kennedy, an Environmental Health Specialist with the Ventura County Environmental Health Division.
By following these guidelines you’re doing your part to protect your local waterways while keeping your pool clean.
David Laak is the Stormwater Resources Manager with Ventura County Public Works Agency – Watershed Protection District and David Goldstein is an analyst with the Waste Management Division
