Swimming Pools, Hot Tubs and Spas
Throughout this Web site, "pool" or "pools" will be used in reference to swimming pools, hot tubs or spas operated on private, residential properties, both indoors and outdoors.
The City of Toronto’s sewer system
The City of Toronto has different types of sewer systems.
- A sanitary sewer carries the water from the drains and toilet in your home to the City’s wastewater treatment plant for treatment before it is released into Lake Ontario, several kilometres from shore
- Toronto also has storm sewers which carry rain and melted snow away from houses and roads through large grates on the ground, known as catchbasins. Anything entering a catchbasin enters the storm sewer system and goes directly into the nearest creek, river and, eventually, Lake Ontario. This water, referred to as stormwater, is not treated.
- In some older parts of the City, there is a combined sanitary and storm sewer system. During times of heavy rain, these sewers may overflow, wastewater may mix with stormwater, and may even be discharged into Lake Ontario without proper treatment.
Toronto is working to better manage stormwater in the City through the Wet Weather Flow Master Plan and other initiatives.
Your responsibility
As the owner of a private swimming pool, hot tub or spa, you (and any pool service providers you hire) have a responsibility and legal obligation to safely maintain and operate your pool, hot tub or spa in compliance with the City’s Sewer Use By-law (also known as Municipal Code Chapter 681-Sewers).
The City of Toronto sets out requirements for the proper operation, maintenance and seasonal closure of pools, hot tubs and spas that will protect the quality of water in Lake Ontario and, ultimately, your drinking water quality.
The City’s pool discharge requirements are set out in the “Environmental Best Management Practices (BMP) for Swimming Pools and Hot Tubs/Spas”. This BMP will provide you with what you need to know about operating your pool, hot tub or spa in compliance with the City’s Sewer Use By-law and the BMP.
As well, you (or your hired pool service provider)are legally obligated to report a spill to provincial and municipal authorities if your pool water has been spilled into a stream, river, lake or the storm sewer systems (without proper treatment).
The City of Toronto’s responsibility
The City of Toronto has a responsibility to ensure compliance of the Sewers Bylaw and to protect the environment. This may include inspections,examinations and collection of wastewater samples for analysis. If necessary, the City may also order corrective measures under the authority of the Toronto Municipal Code Chapter 681 and,if needed, take matters to court.
Why is water from chlorine and salt water pools a concern?
The water from pools is filled with chemicals you need to keep your pool clean and safe for swimming. The main chemicals found in pools are chlorine/bromine, salt, copper-based algaecides,nonylphenols and nonylphenol ethoxylates. These chemicals are harmful to the fish and organisms that live in the creeks and rivers across Toronto and Lake Ontario. The thousands of residential pools in the City of Toronto can have a significant negative impact on creeks, rivers and ultimately Lake Ontario. That is why Toronto sets requirements on how to discharge pool water.
Where should I discharge the water from my pool?
The water from chlorine pools must be dechlorinated prior to discharging to the storm sewer system. But this should not be done during a rainy day as it will overwhelm the storm sewer system.
The water from salt water pools has such high levels of chlorides that this water cannot be discharged to the storm sewer system—it must be carefully discharged to the sanitary system connection located on your own property.
The water from both chlorine and salt water pools can also be discharged onto your property surrounding your home, if it can be properly absorbed into the ground without flowing onto your neighbour’s property. Before trying this option, you must consider the slope and surfaces of your property, as well as the proper rate to discharge the pool water so it will be fully absorbed on your own property (not run off onto neighbouring property). If discharging to the sanitary sewer system or onto your property is not possible, salt water pool water must be hauled by a Ministry of the Environment-approved hauler.
Rain water or melted snow collected on your pool cover can be discharged to the storm sewer system as long you remove leaves and other debris first.
The backwash water from the filter must be filtered and dechlorinated if going to storm sewers, otherwise it must be discharged to the sanitary sewer or onto your surrounding property if it can be properly absorbed into the ground.
By keeping Lake Ontario healthy, we are ensuring that we have a safe source from which to produce our drinking water.
Ravines and Valleys
Pool water (of any kind) can never be discharged into a ravine or valley, or onto the ground near to a ravine or valley. Pool water will cause erosion to the land banks and serious damage to vegetation.
More information
Download a copy of the:
- Environmental Best Management Practices (BMP) for Pools and Hot tubs/Spas (PDF)
- Sewer Use By-law (PDF)
- Swimming Pools, Hot Tubs and Spas brochure (PDF)
The Pool and Hot Tub Council of Canada is supportive of the City’s new measures to regulate pool discharges into the sewer system.
Toronto Water
Environmental Monitoring & Protection Unit
30 Dee Avenue
Toronto, ON M9N 1S9
Tel: 416-392-9940
Email: p3help@toronto.ca
To report a pool water spill call:
- Ministry of Environment 24-hour reporting number:
Tel: 416-325-3000 - Toronto Water 24-hour reporting number:
Tel: 311.