A Toronto Water Bill That Suddenly Jumped: Leaks, Meter Tests and Who Gets an Adjustment

Who pays comes down to one of three findings: the City’s equipment was off, your plumbing leaked, or nobody can say why. Each one sends the bill in a different direction.

Lift the lid off the toilet tank, add a few drops of food colouring, and don’t flush. Come back 10 to 15 minutes later. If the water in the bowl has turned the same colour, the tank is leaking into the bowl, day and night, and every litre of it passes through the meter and onto your bill. That’s the City of Toronto’s own dye test, and it is probably the cheapest piece of evidence you will gather after a utility bill that makes no sense.

I’m Arthur Zhao of AZ Real Estate Partners. A coloured bowl answers one question, where some of the water went. It doesn’t answer the one owners actually care about, which is who ends up paying for it. In Toronto that depends on which of three findings your investigation ends in, and on doing a few things in the right order while the bill’s due date keeps running. This article walks through the rules in Chapter 849 of the Toronto Municipal Code and the City’s own pages, finding by finding.

Why Toronto bills jump: run down the list before you blame anyone

The City’s High Water Bill and Leaks page lists the usual reasons a bill rises suddenly: leaks in toilets or fixtures; more people living or working in the home; a dry, hot summer; more days in the billing period; renovations, new landscaping or filling a pool; and several estimated readings followed by an actual one. The last item catches people out. Chapter 849 (§849-31D) lets the City bill on an estimate based on your daily average over a similar period, and when a real reading finally arrives, whatever you used above the estimates lands on one bill.

That catch-up risk is higher right now. The City’s water-meter pages carry a notice that many MTUs (meter transmission units) have stopped sending water-use data to the City because of a technical issue, and some owners are getting mailed notices asking them to send in an actual meter reading.

Then check for a leak yourself. Besides the toilet dye test, the City’s leaks page suggests turning off every indoor and outdoor tap and watching the meter face: if the flow indicator (a red triangle or black star) still moves, something downstream is using water. MyWaterToronto shows use by day, week, month or year, but if your transmitter has stopped reporting, recent days may not show up there. The stakes are not small. According to the City’s leaks page (2026), a leaky toilet can waste up to 20 cubic metres a day.

If what started all this was a City letter about unusual consumption, the page lists Water Investigation at 416-395-0177 for questions about that letter.

While you investigate, the collection clock keeps running

The collection steps don’t wait for your findings. Under Chapter 849, §849-33, measured from the bill’s due date:

• 14 calendar days unpaid: the City may mail an overdue notice.
• 28 calendar days unpaid: the City may mail a transfer to tax notice, giving you 30 calendar days from the notice date to pay in full. After that, the arrears can be moved onto the property tax roll, with collection charges added.

The City’s late-payments page describes the next step as a notice sent when the amount is 58 days past due: the overdue balance and a fee have been added to your property tax account, penalty and interest apply if it stays unpaid there, and from then on payment has to go to the tax account rather than the utility account. As a last resort, §849-33D also lets the City shut off water after notice and with regard to Chapter 835 (Discontinuance of Vital Services), where it decides other collection steps are not workable.

Finding one: the meter or the City’s equipment was wrong

This is the only finding where the by-law lets the City correct its own mistake. Under §849-28A, where the CFO determines that a meter is defective, that a remote read-out unit is recording inaccurately, that a meter’s dial capacity coding is wrong, or that the account is wrong because of any other error by the City or City-owned equipment, the CFO may adjust the account. The adjustment uses actual consumption if it can be determined, or otherwise an estimate. The by-law also caps how far back it can go: the adjustment can’t cover a period of more than one year. Separately, §849-31C says that if the meter’s own register and the remote read-out disagree, the register on the meter is treated as the correct reading.

How do you get there? The City’s Water Meter Accuracy page sets the order: check for leaks, call 311 so a Revenue Services representative can review the account with you, and only then book a meter accuracy test at 416-338-1616 if you’re still concerned. Staff remove your meter, install a new one and reprogram the transmitter, then test the old meter at a Toronto Water facility at different flow volumes. The meter is kept in storage for three months, and results are mailed within three to four weeks.

The test costs you money unless the meter turns out to be over-registering. If the meter is over-registering, the City credits your account for the over-registered amount on your next bill. If it is accurate or under-registering, a meter testing fee goes on your next bill. The City’s 2026 fee schedule lists $220.42 for a meter of 50 mm or less with no chamber, applied if the meter does not over-register. The City reviews its fees every year, so check the current schedule before you book.

Finding two: your own plumbing leaked

Here the starting rule is blunt. Under §849-27B, even though water was lost or never used because of a break, malfunction or leak in a private water system, the owner is liable for all the water fees on that water. The private water system is everything downstream of the meter (§849-26), and the City’s Water Meters page says plainly that the City isn’t responsible for leaks in those pipes or in the main shut-off valve. Fixing the leak stops the bleeding from that point on; it doesn’t by itself change the bill you already have.

The one exception is narrow. Under §849-31G, the Controller may reset that billing period to the historical average for the same or a similar property, if the Controller finds an uncontrollable consumption increase (use three or more times the property’s historical daily average, from a cause that may be known but is beyond your reasonable control) and paying it would cause undue financial hardship. The City’s page describes this category as one caused by a leak or other defect in the private plumbing system. Every condition has to be met:

• you are a low-income person. The by-law counts the combined gross income of everyone living in the home. According to the City of Toronto’s High Water Bill and Leaks page (2026), the current line is household income less than $62,000, and that figure can change, so check the page when you apply. The City may ask for an unaltered Notice of Assessment or Notice of Reassessment;
• neither you nor anyone in your household has received a §849-31F or §849-31G adjustment for the property before;
• you live there and have lived there for at least one year immediately before both the consumption event and your request;
• the property is not tenanted, and it is in the residential property tax class (the City’s page says assessed solely as residential).

You also have to hand over whatever information about the plumbing, the occupants and the period’s water use the Controller asks for, and City staff may inspect the property.

Finding three: no one can find a cause

Suppose the meter is fine, nobody in the house changed anything, and the number still tripled. Chapter 849 has a name for that: an unexplained consumption increase (§849-26). It is a strict definition with three parts, all of which must be true:

• use for the billing period was three or more times the property’s historical daily average;
• the meter has been tested and found accurate and free of defects, and the Controller finds no other City activity could reasonably have caused the increase;
• the Controller finds the increase can’t reasonably be put down to anything done or not done by you, an occupant or someone under your control, or to a leak or other defect in your private plumbing.

That second point means the meter test from finding one is a step you take on the way here, not an alternative. To show the third point, you must supply, at your own cost, written verification from a plumbing contractor licensed to carry on business in Toronto stating that the private plumbing system is free of leaks or other defects that could affect consumption and that, after careful inspection, nothing else explains the increase. You also provide any information the Controller asks for, and City staff may inspect.

If the Controller is satisfied, §849-31F allows the billing period to be reset to the historical average for the same or a similar property, on the same occupancy conditions as the hardship route: no previous §849-31F or §849-31G adjustment, at least one year living there immediately before the event and the request, and a property that is not tenanted. Unlike the hardship route, there is no income test.

Where the cause sits decides almost everything

How to put in a request

Chapter 849, §849-31H says a request under §849-31F or §849-31G must be made in writing to the Controller, clearly setting out why you’re asking and enclosing all the necessary documents and information. The City’s High Water Bill and Leaks page asks for supporting documents by mail to:

City of Toronto, Revenue Services, Utility Billing, 5100 Yonge St., Toronto, ON M2N 5V7

Say which finding you’re relying on and why. For an unexplained increase, include the meter test result and the plumber’s written verification. For the hardship route, include the income documents and what you know about the cause. In both cases, show that you’ve lived there for at least a year and that the property isn’t rented out. §849-31H covers those two one-time adjustments. For a suspected City-side error, the City’s meter page sends you through 311 and the meter accuracy test instead, so keep a written note of the date of your 311 review and the test result.

These rules apply to the City of Toronto only. The decision belongs to the City; if your account raises a question of law, talk to a lawyer about your own situation.

Who to call, and what to ask each of them

Grouped by whose door you are knocking on, so each call covers everything that party can actually help with.