Why is my water heater leaking from the bottom?
Standing water under the tank, a damp ring on the floor, or rust streaks running down the outside of the jacket.
This one can get worse fast. Call before it spreads.
Key takeaways
- This is an emergency. Shut things down and call a plumber now rather than waiting.
- Most likely cause: Corroded tank.
- Do this first: Close the cold water shutoff valve on the pipe entering the top of the heater.
- Call right away if water is spreading across a finished floor or into a wall cavity.
- The repair starts with: Isolate water and fuel to the heater.
What it is
Water heater leaking from the bottom A bottom leak on a water heater means water is pooling under or dripping from the base of the tank, most often because the steel tank has corroded through and can no longer hold water.
This needs immediate action because a corroded tank fails without warning, so close the cold water shutoff valve on top of the heater and cut its gas or breaker now.
The short answer
Water leaking from the bottom of a water heater usually means the tank itself has corroded through, and a corroded tank cannot be repaired. It has to be replaced. Before anything else, shut off the cold water supply valve on top of the heater and cut the gas or the breaker. A slow drip today can become a full tank on the floor within hours, so treat a bottom leak as urgent.
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What it usually means
These are the causes we find most often, ranked from most likely to least.
- 1
Corroded tank
Most likely
The steel tank has rusted through from the inside. Replacement is the only fix.
- 2
Temperature and pressure relief valve discharging
Common
The valve is doing its job because pressure or temperature is too high. That is a system problem, not just a valve problem.
- 3
Leaking drain valve at the base
Common
The plastic drain valve weeps after a flush or with age. Often a repair rather than a replacement.
- 4
Condensation on a high efficiency or newly filled tank
Less common
Cold incoming water can sweat the tank. It clears once the water warms.
- 5
Loose fittings above the tank draining down the jacket
Occasional
A supply connection leak runs down the outside and looks like a bottom leak.
What to do right now
- 1Close the cold water shutoff valve on the pipe entering the top of the heater.
- 2Turn the gas control to off, or switch off the water heater breaker.
- 3Move stored items away from the tank and protect flooring and drywall.
- 4Do not try to drain a hot tank. Let it cool or have a plumber handle it.
When it is an emergency
- Water is spreading across a finished floor or into a wall cavity.
- The leak is near an electrical panel, outlet, or furnace.
- The relief valve is discharging hot water continuously.
What the fix involves
A leak from a fitting or a drain valve is a repair. A leak from the tank body is a replacement, and the replacement is the moment to confirm the new unit is sized correctly, properly vented, and fitted with an expansion tank where code requires one.
- 1Isolate water and fuel to the heater.
- 2Trace the leak to the fitting, the valve, or the tank body.
- 3Repair the fitting or valve where the tank is sound.
- 4Drain and remove the failed tank and install the replacement to current code.
What drives the cost
Every job is quoted before work begins. These are the factors that move the number on this kind of repair.
- Repair of a valve versus full tank replacement
- Tank capacity and fuel type
- Water damage cleanup and access in tight utility closets
- Required code upgrades such as venting, pans, or expansion tanks
- Emergency or after hours dispatch
The service that fixes this
Related problems homeowners ask about
Why do I have no hot water?
Taps run cold at every fixture, or hot water disappears after a minute or two. The heater may be silent, or it may run without ever heating the tank.
Read this nextWhy is my water heater making a popping noise?
Popping, rumbling, or kettle-like sounds from the tank during a heating cycle, often loudest after heavy hot water use.
Read this nextWhat causes a ceiling stain under an upstairs bathroom?
A brown ring, a soft or sagging spot, bubbling paint, or active dripping on the ceiling directly under a bathroom.
Read this next
Read more on this
This page is for triage and dispatch. These guides go deeper on how the work is done and what shapes the price.
Licenses, credentials, and company proof
- Colorado Master PlumberLicense MP-18927
- Colorado State Plumbing ContractorLicense 2110
- Family Owned & OperatedServing Denver since 2006, 20 years
- Better Business BureauAccredited Business, A+ rating
- Angie's List Super Service Award2012 through 2017
- Serving Denver since 2006Residential and commercial properties across the metro
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Straight answers on what water heater leaking from bottom work costs, how fast we can get out, and what stands behind the repair.
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