By Erwin Just
We have all seen it happen; pool water pumped into the sewer under the cover of darkness. The reason? In most municipalities, including the city of Toronto, it is against the law to discharge untreated pool water into storm sewers.
In Toronto, the sewer use bylaw, a.k.a. City of Toronto Municipal Code Chapter 681, sets the allowable limits for swimming pool discharge entering storm sewers as follows:
- Chlorine, 0.01 mg/L (milligrams per litre)
- Bromine, 0.01 mg/L
- Copper, 0.04 mg/L
- Salt (sodium chloride), Nil
- pH, 6 to 9.5
- Acid wash must be neutralized to storm sewer pH limits.
(Note: 0.01 mg/L essentially means zero—no chlorine or bromine is allowed into the storm sewer. More information on discharge limits can be found at www.toronto.ca/water/protecting_quality/pollution_prevention/swimmingpools.htm.)
To help pool professionals understand and comply with the city’s bylaw, it developed, in conjunction with the Pool and Hot Tub Council of Canada (PHTCC), the Environmental Best Management Practices (BMP) for Swimming Pools and Hot Tubs/Spas.
The BMP outlines why aquatic species must be protected from toxins found in pool water and specifically what is required of the industry in order to comply with regulations.
However, some confusion remains as to what is permitted under Toronto’s sewer use bylaw—and which maintenance practices, if any, need to be changed. Based on this author’s experience, the following are some of the key issues that need to be addressed by the pool industry.
Fact versus fiction
Issue: Pool water can be pumped into the storm sewer if left with no chlorine for one week.
In practice: Although this may be true in some cases, pools left for more than a week will still have a chlorine reading above the city’s storm sewer limit. The pool may even become cloudy or green, with only the slightest trace of chlorine. In order to pump pool water into the storm sewer, the discharged wastewater must be tested to ensure it is below 0.01 mg/L, while at the same time keeping all other parameters within city guidelines.
Issue: Algae treatment—The method used to clear a green pool is generally to shock it and add an algaecide. In doing so, pools frequently reach more than 20 parts per million (ppm) of chlorine. Once the algae is dead and has fallen to the bottom of the pool, the water is commonly vacuumed out into the street and the storm sewer. When it comes time to close the pool, owners will often drain the water immediately after treating it with large amounts of chlorine and algaecide, sending it straight into the storm sewer, unaware the discharge does not comply with the bylaw.
In practice: The treatment of algae in swimming pools may pose a greater risk to the aquatic environment than winterizing due to the extremely high chlorine and algaecide levels in the water. Granular chlorine neutralizer should be directly added to the water to reduce the chlorine level to zero, while wastewater discharge should be tested to ensure it meets all storm sewer limits.
