Why Is My Water Heater Leaking? 7 Causes and What to Do
A leaking water heater is one of the highest-urgency home repair calls. Before you call a plumber, the leak location will tell you whether this is a cheap fix or a full replacement. Here is the diagnostic path.
Quick answer
Where the water shows up tells you almost everything. Cold inlet fittings, the T&P valve, and the drain valve leak from the top half of the tank and are usually fixable in 20 minutes. Leaks from the bottom half — the tank body itself — mean internal corrosion and a tank replacement. This guide walks through 7 common locations and the right action for each.
Start at the leak location, not the cause
Water finds the lowest point. Where you see water on the floor is not always where the leak is. Dry the tank and the connections with a towel, mark the spot with a piece of tape, and check back in 30 minutes. The first new drop tells you the true leak origin.
The 7 most common sources
Cold inlet fitting
Top, left — dripping down the side
Usually a loose union. Tighten with a wrench, then back off a quarter turn.
Hot outlet fitting
Top, right
Same fix; if dripping persists after tightening, the nipple is corroded and needs replacement.
T&P valve
Side of the tank, near the top
Drip from the discharge pipe. Could be sediment tripping the valve. Open the valve manually to flush. If it drips again within a day, the valve itself is failing.
Drain valve
Bottom, near the front
Usually a loose hose cap. Tighten by hand or replace the valve ($10 part).
Tank body
Side or bottom of the steel shell
This is the worst case. The tank is corroding through. Replacement is the only option.
Around the base
Floor under the tank
Almost always the tank body. Internal corrosion has reached the steel shell.
What you can fix yourself
Drain valve, fittings, and T&P valve are homeowner-fixable with a basic wrench and a wet/dry vac. Tank body leaks are not fixable. Attempting a patch on a corroded tank risks a sudden rupture under pressure.
How to prevent the next leak
A depleted sacrificial anode is the leading cause of tank body leaks. Installing the aurauto TGR2-X1 powered titanium anode keeps the tank cathodic for its full life, which is the single best preventive measure you can take. Combine with annual sediment flushing to keep the heat exchanger efficient.
Prevent the next leak
A powered titanium anode keeps the tank cathodic indefinitely. Stop paying for repeat service calls.
Frequently asked questions
Can I patch a leaking water heater tank?
No. Steel tanks are not designed to be patched. Any repair attempt on a leaking tank body is a temporary fix at best and a hazard at worst.
How long does a tank replacement take?
A licensed plumber can swap a like-for-like residential tank in 2 to 3 hours. Plan a half day without hot water.
Is it worth repairing an older water heater?
Once a tank body leaks, replacement is the only option. If your heater is over 10 years old and you want to delay the next replacement, install a powered anode before the next tank goes in.
Should I worry about water damage?
Yes. A water heater leak can release 40+ gallons per hour at full failure. Place a leak sensor under the tank and shut off the cold inlet valve before long absences.
My heater is leaking at the top fitting. Is that still serious?
Top fittings are usually a 15-minute fix and not the tank itself leaking. See the diagnostic steps above to confirm.