Draining Your Backyard Pool in Toronto: Where the Water Can Go and What the Sewer By-law Says
Toronto’s sewer by-law asks one question before any other: is it a salt-water pool or a chlorine pool? The answer decides which routes are open to you.
Can I drain my pool into the storm sewer in Toronto?
Only if all five conditions in §681-11T(3) of Toronto’s sewer by-law are met, and only for a conventional (non-salt) pool. A salt-water pool cannot use the storm sewer at all. The five conditions include no algaecides, holding the water for one week after the last chlorine dose, treating it with sodium sulphite to bring chlorine to 0.01 mg/L or less, and copper at or below 0.04 mg/L.
Source: City of Toronto Municipal Code Chapter 681, Sewers, §681-11T and §681-11U (consolidated to May 21, 2026)
I’m Arthur Zhao, a Toronto real estate Broker. Picture a buyer who closed in the spring on a house with a salt-water pool. The summer is over, the pool needs to come down, and the question is simple: the previous owner said they just ran a hose out to the back lane and let it go to the drain at the curb. Can I do the same?
What a previous owner did tells you nothing about whether it was allowed. Toronto’s sewer by-law, Municipal Code Chapter 681, has a specific set of rules for pool water, and for a salt-water pool the answer to that question is no. Here is how the rules are laid out, starting with the question the by-law itself asks first.
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First question: is it a salt-water pool?
Chapter 681 splits pool drainage into two separate sections by pool type. §681-11T covers private residential “conventional non-salt water” swimming pools, hot tubs, spas and wading pools. §681-11U covers private residential salt-water pools and hot tubs/spas.
For a salt-water pool, §681-11U(1) says no person shall discharge the wastewater except in one of two ways:
- To the sanitary sewer, by a permanent or a temporary connection to the sanitary drain on the owner’s property; or
- By a controlled discharge onto the owner’s property, contained there at all times until it evaporates or soaks into the ground, and without migrating onto adjacent lands.
That is the complete list. The storm sewer is not on it, and §681-11U has no exception that adds it back. So for the buyer in the opening: if the water from the back lane would end up in a curb drain that feeds the storm system, that route is not one §681-11U permits. (The chapter speaks of the “storm drainage system” and “storm sewer” without naming each grate or catch basin; whether a particular drain connects to the storm system is a question for the City.)
How the sanitary connection is physically made on your property is something the by-law does not spell out. For that, ask a licensed plumber or call the City at 311.
💡 My own view is that pool type belongs on the list of things to confirm when you buy a house with a pool. Ask the seller, or have the pool checked, to find out whether it is salt water or chlorine, and ask how it has been drained until now. A salt-water pool has the narrower set of drainage routes under Chapter 681, and it is better to learn that before closing than in late September with a full pool.
A conventional chlorine pool: the two default routes
If the pool is not salt water, §681-11T(2) gives two routes that are always available, before you get to any exception:
- A temporary connection to the sanitary sewer (§681-11T(2)(a)); or
- A controlled discharge onto the owner’s property, contained within the property at all times until it evaporates or infiltrates into the ground (§681-11T(2)(b)).
Read side by side, these track the salt-water routes in §681-11U (which also allows a permanent sanitary connection). The difference is what comes next: a chlorine pool has a third, conditional route that a salt-water pool does not. §681-11T(1)(d) also closes the door on anything else, since discharging “in a manner other than is permitted under § 681-11T(2) or (3)” is prohibited.
Sanitary sewer or storm sewer: how Chapter 681 treats each for pool water
The storm sewer exception: five conditions, all at once
According to the City of Toronto’s Municipal Code Chapter 681 (2026), a person may discharge wastewater from a private residential conventional pool, hot tub/spa or wading pool to a storm sewer “provided that all of the following conditions are met.” The five conditions are joined by “and,” so meeting four of them is not enough:
- No algaecides in the pool water (§681-11T(3)(a)).
- The water is held in the pool for one week after the last dosage of chlorine, and the chlorine concentration in the wastewater is at or below 0.01 mg/L (§681-11T(3)(b)).
- The water is treated with sodium sulphite to achieve the 0.01 total chlorine limit (§681-11T(3)(c)).
- The copper concentration is at or below 0.04 mg/L (§681-11T(3)(d)).
- The owner, either directly or through a tenant, operator or service contractor, complies with the City’s Environmental Best Management Practices for Swimming Pools; where that document and Chapter 681 differ, the chapter governs (§681-11T(3)(e)).
The whole of §681-11T(3) is also “subject to § 681-11U,” which is the by-law’s way of saying a salt-water pool cannot borrow this exception.
The by-law sets the limits but not the method: it does not say how much sodium sulphite to use, how to test, or how fast to pump. For those details, ask a pool professional or the City.
Filter backwash and rainwater on the cover
Two kinds of pool water have their own rules, and both apply “notwithstanding” the sections above.
Filter backwash (§681-11W). The backwash water from the pool filter must go to the sanitary sewer or onto the owner’s property, in a manner that does not flow onto the street or a neighbouring property (§681-11W(1)). The same section requires the owner, directly or through a tenant, operator or service contractor, to comply with the City’s Environmental Best Management Practices for Swimming Pools and Hot Tubs/Spas (§681-11W(2)). The storm sewer is not one of the routes listed for backwash.
Rainwater sitting on the tarp (§681-11V). Rain that collects on a tarp covering a pool, hot tub/spa or wading pool may be discharged to a storm sewer, subject to §681-4 (the chapter’s general storm sewer requirements) (§681-11V(1)). This applies to clean rainwater on the cover, not to the pool water underneath it. And no water, tarp rainwater included, may be discharged to or near a ravine so that it flows to the ravine in a way that may cause erosion or instability of the valley or ravine slope, or that injures or destroys trees and vegetation (§681-11V(2)).
⚠️Backwash is not a storm sewer discharge. Under §681-11W(1), water from backwashing the pool filter must go to the sanitary sewer or onto your own property, and it must not flow onto the street or a neighbouring property. A backwash hose aimed at the curb does not fit either route.
What is never allowed, whichever route you choose
Even when the route itself is permitted, §681-11T(1) sets limits on how the water travels. For a conventional pool, hot tub/spa or wading pool, no person may discharge the wastewater:
- in a manner that causes, or may cause, it to flow onto an adjoining property (§681-11T(1)(b)); or
- over a valley or ravine wall or slope in a manner that causes, or may cause, erosion or instability of that slope (§681-11T(1)(c)).
Note the words “may cause.” On the text, the prohibition reaches discharge that is likely to run onto the neighbour’s lot or down a ravine slope, not only discharge that already has.
For salt-water pools, the same idea is built into the route itself: a discharge onto your own property must stay there until it evaporates or soaks in, and must not migrate onto adjacent lands (§681-11U(1)(b)). If your lot slopes toward a neighbour or backs onto a ravine, the “contain it on my own property” route needs a hard look before you rely on it.
Penalties under Chapter 681
According to the City of Toronto’s Municipal Code Chapter 681 (2026), §681-14.1, the maximum fines apply upon conviction. These are ceilings a court can impose, not fixed amounts:
- An individual who contravenes a provision of the chapter: up to $50,000 for a first offence and up to $75,000 for any subsequent offence (§681-14.1A(1)).
- A corporation: up to $100,000 for a first offence and up to $100,000 for any subsequent offence (§681-14.1B).
- A continuing offence: up to $10,000 for each day or part day the offence continues, and the total of the daily fines “shall not be limited to $100,000” (§681-14.1C).
- A special fine: anyone who gains an economic advantage or gain from the contravention is liable, on top of the other fines, to a special fine equal to the fair market value of that advantage or gain (§681-14.1E).
The by-law text does not tell you what fine a court would actually set in a given case. If you have received a notice or charge, speak to a lawyer about your specific situation.
Before you pull the plug
A short list to work through, based on the sections of Chapter 681 above.
- ☐Confirm whether the pool is salt water or conventional chlorine, since §681-11U and §681-11T set different routes.
- ☐Check whether algaecides have been added this season; their presence rules out the storm sewer (§681-11T(3)(a)).
- ☐Walk the path the water would take and make sure none of it can reach a neighbouring lot or a ravine slope (§681-11T(1)(b)–(c)).
- ☐Ask a licensed plumber or call 311 about how a temporary sanitary connection is made on your property.
- ☐Direct filter backwash to the sanitary sewer or your own lot, never onto the street (§681-11W(1)).
- ☐Stop adding chlorine and hold the water in the pool for one week after the last dose (§681-11T(3)(b)).
- ☐Treat the water with sodium sulphite to bring total chlorine to 0.01 mg/L or below (§681-11T(3)(b)–(c)).
- ☐Test copper and confirm it is at or below 0.04 mg/L (§681-11T(3)(d)).
- ☐Follow the City’s Environmental Best Management Practices for Swimming Pools; where it conflicts with Chapter 681, the chapter governs (§681-11T(3)(e)).
A note on condo and apartment-building pools
Both §681-11T and §681-11U apply to “private residential” pools, and each section defines that term the same way: a pool serving five or fewer single-family residences (§681-11T(4), §681-11U(2)). If a pool serves more residences than that, as a condominium or rental building pool may, it falls outside those two definitions, and the drainage routes described above are not written for it. The sections reviewed here do not say which rule applies instead; the building’s management and the City are the ones to ask.
Toronto’s Mandatory Downspout Disconnection: Which Homes Must Comply and When an Exemption Applies →Buying a House With a Pool in the GTA: Real Costs, Insurance, and the Fence Bylaw →Backyard Chickens and Beehives in Toronto: What the City Animal Bylaw and Ontario’s Bees Act Allow →The Ontario Selling Blueprint →
Frequently Asked Questions
Do the same rules apply to my hot tub?
Yes. The headings of §681-11T and §681-11U in Toronto’s Chapter 681 name hot tubs and spas alongside swimming pools, and §681-11T also covers wading pools. A conventional hot tub follows §681-11T, including the five storm sewer conditions; a salt-water hot tub/spa follows §681-11U and its two routes.
Can rainwater that collects on my pool cover go down the storm drain?
Under §681-11V(1) of Chapter 681, rainwater resting on a tarp that covers a pool, hot tub/spa or wading pool may be discharged to a storm sewer, subject to the chapter’s general storm sewer rules in §681-4. That permission is for the rainwater on the cover, not the pool water below it, and §681-11V(2) still bars sending any water to a ravine in a way that may erode the slope or damage trees and vegetation.
If my tenant drains the pool the wrong way, am I responsible?
Chapter 681 places the duty to follow the City’s best-practices document on the owner, “either directly, or through a tenant, operator or service contractor” (§681-11T(3)(e) and §681-11W(2)). The drainage prohibitions themselves say “no person shall discharge,” so on their wording they reach whoever does the discharging. Who could be charged in a particular case depends on the facts, so a lawyer is the right person to ask if it comes to that.
Does this apply to the pool in my condo building?
§681-11T(4) and §681-11U(2) define a “private residential” pool as one serving five or fewer single-family residences. If your building’s pool serves more residences than that, it falls outside those definitions and the routes in this article are not written for it. The sections reviewed here do not say what applies instead, so check with your condo management or the City.
If my chlorine is already down to 0.01 mg/L, do I still need sodium sulphite?
On the text, yes. §681-11T(3) requires “all of the following” conditions, joined by “and”: condition (b) requires holding the water one week after the last chlorine dose with chlorine at or below 0.01 mg/L, and condition (c) separately requires treating the water with sodium sulphite to achieve that 0.01 limit. The by-law does not offer one as a substitute for the other.
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