Water is leaking from the water heater

Q: Water is leaking from the water heater

In Canada, when a tank water heater leaks, the first job is to find where the water is coming from, not to assume the worst. A weeping drain valve at the bottom and loose pipe fittings at the top are common and inexpensive to fix; water on a cold new tank is often just condensation. A drip from the valve and pipe on the side is the temperature & pressure (T&P) relief valve doing its job — a warning sign to take seriously, never something to cap. Rust weeping from the tank body itself means the tank has reached end of life and must be replaced by a licensed plumber. If water is pooling fast near the gas burner or the electrical connections, shut off the water and the power or gas and call a plumber; if it's a gas unit and you smell gas, leave and call your gas utility.

A little water near the tank is worth tracing calmly — a lot of the time it's a loose valve or harmless condensation, not a burst tank.

tuneWhat are you noticing?

Select anything that matches and the checklist below reorders to fit. Not sure? Skip it.

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Start here

In Canada, the cheapest thing to rule out first is the drain valve at the bottom of the tank. Dry it off and watch: a bead of water forming right at the valve means it isn't sealing — often just from a past draining. A gentle snug, a brass garden-hose cap on the outlet, or a replacement valve usually settles it. Wipe it, wait, and see where the water actually starts.

Ranked from real-world failure data. The order updates as you select what you’re noticing above.

Likely causes, in the order to check them

Showing the typical order

Beginner-friendly Doable, with care Safety-critical Call a pro

handymanHow to fix it

Confirm the drip is at the drain valve, gently snug it closed, and if it still weeps, thread a brass garden-hose cap onto the outlet as a reliable seal — or replace the valve if it won't hold. No hot draining is needed for a cap.

Dry the valve and the floor, then watch to confirm the water truly starts at the drain valve and not higher up on the tank.
Make sure the valve is fully closed — turn the handle or knob gently clockwise. Do not force a stuck plastic valve; it can crack.
If it still weeps, hand-thread a brass garden-hose cap onto the valve outlet and snug it with pliers. This seals a valve that no longer closes fully, without draining the tank.
If the valve body itself is cracked or leaking, plan a valve replacement — that one does require draining the tank, so read a full replacement guide or call a plumber.

schedule20 min savings$5–40

Brass garden-hose cap (3/4" GHT)Match the standard 3/4" hose-thread outlet on the drain valve; brass seals better than plastic

verifiedWhy this one goes to a pro

Once the steel tank has corroded through, no sealant or clamp makes it safe — it will keep failing and can let go suddenly while full of hot water. Replacement means correctly sizing the new unit, safely disconnecting the water and the gas or electrical supply, and meeting the local permit and inspection rules. In every province this is licensed work: a plumber for the tank, and a gas-fitter for the gas connection on a gas unit.

gavel Check your province first AB: permit + inspection required · BC: permit + inspection required · ON: permit + inspection required · PE: licensed professionals only · QC: licensed professionals only
Water-heater tank replacement is licensed work across Canada, with gas hookups reserved for licensed gas fitters. Confirm the province's permit and inspection requirements.

Your notes travel with the request — what you saw, what you ruled out, when it started — so the pro arrives with a head start instead of a mystery.

visibilityHow to tell it's the T&P valve

Find the valve on the side or top of the tank with a metal or plastic pipe running down toward the floor — that's the temperature & pressure (T&P) relief valve.
Dry the discharge pipe and its opening, then watch: water appearing at the pipe means the valve is releasing. It often does this during or just after a heating cycle.
Note whether the water is hot and whether it recurs. Steady or hot discharge points to the tank running over-temperature or over-pressure — a real condition to fix, not the valve's fault.

buildflashlight schedule10 min

visibilityCondensation or a real leak?

Dry the whole tank and the floor around it completely, then note the time — especially if the tank is new or was just filled with cold water.
Watch through a full heating cycle. Fine droplets that bead over the cool tank surface and then vanish as it warms up are condensation, and are normal in a humid basement.
Water that keeps returning to the same spot, runs in a steady trail, or pools after the tank is hot is a real leak — trace it up to its highest starting point to find the source.

buildtowel schedule15 min

handymanHow to fix it

Dry the hot and cold fittings, find the joint that beads first, and gently snug it with a wrench while holding the pipe steady. If it's a threaded joint that keeps weeping, it may need re-sealing with fresh thread tape.

Dry both fittings at the top of the tank and watch for which joint a bead of water forms at first.
Hold the fitting steady with one wrench and gently snug the joint with another — a quarter-turn at a time. Over-tightening or twisting the pipe can crack a fitting or worsen the leak.
If a threaded joint keeps weeping after snugging, it likely needs to be opened, cleaned, re-taped with PTFE thread tape, and remade. If that's beyond your comfort, a plumber can reseal it quickly.
Wipe dry and re-check after the next few hot-water draws to confirm the joint stays dry.

schedule25 min savings$0–15

PTFE thread seal tapeFor re-sealing threaded (NPT) water fittings; not needed for compression or union joints

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Why the list is in this order

We don’t sort by likelihood alone. We sort the way a good, honest tradesperson thinks: rule out the free, safe, common causes first. That’s why the cheap checks outrank the expensive repairs — and why anything dangerous gets a hard stop instead of a pep talk. The order exists to save you money, not to sell you anything.