Close your pool without polluting

Having a pool at home is a great way to keep cool during the summer heat. Pool owners know that a lot of work goes into keeping the pool water clean, algae-free and at a safe pH level for swimming. Chemical sanitizers, such as chlorine and sodium chloride, are needed for safe pool operation and maintenance. However, these chemicals can also harm rivers, plants and animals if they are drained directly into the stormwater system from ditches and storm drains on the road.

Learn how to close an outdoor pool for the winter in a safe and responsible way to prevent chemicals from entering the stormwater system and Lake Ontario, the source of Mississauga’s drinking water.

Clean and test the pool water

Skim the surface of the water to remove any leaves, grass clippings and other debris. This will ensure the organic material doesn’t decompose in the pool water over the winter. If there is an automated pool cleaner, remove, drain and dry it before storing it until next year.

Test the pool water to measure its chlorine level and pH. Treat the water to reach a neutral pH of 7.0. Once treated, the water will need to sit for a minimum of seven days without adding chemicals or algaecides. Before draining, confirm that the chlorine level is at zero.

Lower the water level

A swimming pool or spa owner must properly drain their swimming pool or spa in accordance with the City’s Storm Sewer By-law 0046-2022 and Debris and Littering By-law 0219-1985. Drain the pool during dry weather to ensure that the stormwater and sanitary sewer pipes don’t have excess water from recent rainfall. Read the Safe Practices for Pool and Spa Water Disposal for full details.

For in-ground pools treated with chlorine, attach a flexible hose to a pump, ensuring the hose is long enough to reach the curb. Do not drain water onto neighbouring properties. Drain the water level until it is four to six inches below the skimmer, or the filtration system that removes debris from the pool. This will prevent any rain or melting snow from entering the system over the winter, freezing and causing damage.

For salt-water pools and spas, use a hose to slowly empty the water into a sanitary drain inside the house like a basement sink, shower or floor drain. Be careful not to flood the drain or the connection to the sanitary sewer. Never drain salt water onto neighbouring properties or into storm drains on the road. The salt in the water can’t be removed and it can harm rivers, plants and animals if drained directly into the stormwater system.

Soft-sided temporary pools should be fully drained and cleaned. Pipes, pumps and the liner should be drained until dry and stored in a protected area during the winter. It may be possible to leave the collapsed empty vinyl pool in place, if it is covered with a waterproof tarp and protected from pets and weather damage.

Remove equipment and clean filters

Once the water has been lowered, remove ladders, cleaning equipment or pool toys. Rinse them with water and allow them to dry thoroughly, before storing them.

Wipe down the exposed sides of the pool to remove any dirt or residue from the liner. Dispose of any spent pool filter cartridges with regular household waste. Dispose of any hazardous leftover pool chemicals at a neighbourhood Community Recycling Centre.

Winterize the water and install a cover

Chemicals, such as non-chlorine shock and algaecide, can be added to the water that will be left in the pool over the winter. This winterizing treatment helps control the growth of microbes and algae when the water temperature is above freezing. Non-toxic antifreeze can be added to disconnected pool piping, skimmers and pump to resist frost damage. Antifreeze should be removed in spring before start-up.

Lastly, install a winter cover secured across the pool’s surface. This cover will help prevent people and wildlife from falling into the pool, as well as keeping the water as clean as possible until the following year.

For more information about the stormwater infrastructure around your home and in the city, visit mississauga.ca/stormwater.

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• Stormwater