Leaks
Why Is My Water Bill So High? Signs You Have a Hidden Leak in Your Toronto Home
A sudden jump in your water bill almost always means water is escaping somewhere you can't see — here's how to spot a hidden leak and what it costs to fix.
If your water bill has jumped noticeably without any change in how your household uses water, the most likely cause is a hidden leak somewhere in your plumbing. It could be a toilet that's silently running, a pinhole leak in a supply line, or a slow drip behind a wall or under a slab. The good news is that most hidden leaks leave clues, and catching one early can save you from a much bigger repair down the road.
How do I know if I have a hidden leak?
The clearest sign is a water bill that's climbed for two or more billing cycles in a row without a change in your household's habits — no new dishwasher, no extra houseguests, nothing. Beyond the bill itself, watch for a water meter that keeps ticking when every tap and appliance in the house is off. Toronto Water's meter page explains how to read your meter and check for movement; if the dial or digital readout is moving with everything shut off, water is going somewhere.
What are the most common places leaks hide?
Toilets are the number one culprit. A worn flapper valve can let water trickle from the tank into the bowl all day without ever overflowing or making a sound you'd notice. You can test this by adding a few drops of food colouring to the tank — if colour shows up in the bowl within fifteen minutes without flushing, the flapper is leaking. Other common spots include the supply line under a bathroom or kitchen sink, the connection behind a washing machine, and — especially in the GTA's older housing stock — galvanized or copper pipes running through basement walls and crawl spaces that have quietly corroded over decades. In neighbourhoods like The Beaches, Leslieville, and parts of North York where many homes were built between the 1940s and 1960s, aging pipe joints are a frequent source of slow leaks that go undetected until a bill spikes or a ceiling stains.
Can a leak cause damage even if I don't see water?
Yes, and this is the part that catches homeowners off guard. A leak inside a wall cavity or under flooring can soak insulation, drywall, and subfloor for weeks before it's visible, creating the perfect conditions for mould growth. A musty smell in one part of the house, a soft or warped spot in flooring, or a faint discoloration on a ceiling or wall are all signs worth investigating right away rather than waiting to see if they get worse.
What should I do if I suspect a hidden leak?
Start with the toilet flapper test above since it's the easiest and most common fix. Next, check under every sink and behind the washing machine for dampness or mineral staining on the pipes. If those come back clean but your meter is still moving with everything off, the leak is likely inside a wall, under the slab, or in the line between the street and your home — at that point it's worth having a plumber run a proper leak detection check rather than guessing. Camera inspection of main lines typically runs $300–500, and once the source is found, straightforward fixture leaks like a toilet repair usually run $125–275, while more involved pipe repairs vary depending on access.
Frequently asked questions
How much water can a running toilet actually waste? A silently leaking flapper can waste a significant amount of water every single day, which adds up fast over a billing cycle — it's one of the most common reasons for an unexplained spike in a water bill.
Does the City of Toronto offer any help with leak-related water charges? Toronto Water has a process for reviewing high water bills tied to leaks, including in some cases relief programs — details and eligibility are outlined on the City's water billing pages, since the specifics can change.
Is a hidden leak an emergency? A slow leak usually isn't an emergency, but if you see active water pooling, a bulging ceiling, or hear water running inside a wall, treat it like one and shut off your main water valve until a plumber can take a look — burst or actively flowing leaks typically run $350–850 to address.
A water bill that keeps climbing for no reason is your plumbing trying to tell you something — request a plumber or message us on Facebook. Free for homeowners, care of GetFixHero.
Need a plumber in the GTA?
GetFixHero matches Toronto-area homeowners with an available local plumber, usually within the hour. Free for homeowners.
Request a plumber