Water at the base of a water heater does not always mean the tank has failed. It can come from the drain valve, the relief valve discharge pipe, a fitting at the top running down the side, an element gasket, condensation or a clogged condensate drain, all of which can be repaired. Water seeping from the tank shell itself means internal corrosion has broken through, and that cannot be repaired. Shut off the power or gas and the cold water supply first, then find the source.
Why is my water heater leaking from the bottom?
Water runs downhill, so a leak anywhere on the unit often shows up at the base. The location where you first see it, and whether the unit is gas, electric, tankless or heat pump, narrows down the source.
| Where the water appears | Likely source | Repairable? |
|---|---|---|
| A slow drip at the drain valve near the bottom | A worn drain valve or a loose cap | Yes, the valve can be tightened or replaced |
| Water from the discharge pipe beside the unit | The temperature and pressure relief valve opening, or excess pressure from thermal expansion | Usually yes, but find out why it opened |
| Water running down the outside of the tank from the top | A leaking inlet or outlet fitting, union or connection | Yes, the fitting can be redone |
| Moisture or rust at an electric element access panel | A failing element gasket | Yes, the gasket or element can be replaced |
| Water around the base, with no leak on top | Condensation, or a clogged condensate drain on a condensing or heat pump unit | Yes, clear or reroute the drain |
| Water seeping from the bottom seam or under the jacket, with rust | A corroded tank shell | No, the tank must be replaced |
Find the real source of the leak
- Shut off power or gas and the cold water supply, as above.
- Dry the floor and the unit with a towel so any new water is easy to spot.
- Look at the top: pipe fittings, the relief valve and its discharge pipe.
- Look at the middle and bottom: the drain valve, element panels and the jacket.
- Place dry cardboard or paper towels under the unit and check them after a few hours to see where new drops land.
- Wipe cold pipes and the tank to rule out condensation, which forms when cold water meets warm humid air.
If you find a fitting or valve leak, a technician can usually fix it in one visit. If the water seems to come from the tank body, do not wait to see if it stops.
Water leaking from the temperature and pressure relief valve
The temperature and pressure relief valve is designed to open and release water if pressure or temperature gets too high. A valve that opens occasionally can be a sign of thermal expansion in a closed plumbing system, where heated water has nowhere to go, or of high incoming water pressure. A valve that drips constantly may be worn out. Do not cap, plug or restrict the discharge pipe, because that disables the safety function. A technician can check the pressure, the expansion control and the valve itself.
Is it condensation or a leak?
Condensation can pool at the base of a heater in humid conditions, and condensing gas units and heat pump water heaters produce condensate by design that is meant to leave through a drain. The signs of condensation are water that appears only in humid weather or while the unit runs, drips that form on the outside of cold pipes, and no change when the unit has been off. A heat pump or condensing unit with a clogged condensate line can overflow and look like a leak. If the water keeps appearing after you have dried and monitored it, treat it as a real leak.
When a leaking water heater means replacement
A tank is a steel vessel with a glass lining and an anode rod to protect it. Once corrosion eats through the shell, the leak is permanent, and nothing can be patched safely. Signs that the tank itself has failed include water at the seam or the bottom with rust streaks, a puddle that returns after you fix a fitting, and a unit that is also near the end of its typical lifespan. Our guide to how long water heaters last helps you place your unit's age, and our repair or replacement page explains how we weigh the decision. If it is replacement, the work usually needs a plumbing permit in Washington; see our guide to water heater permits.
Can I keep using a leaking water heater?
Not for long. A small leak at a fitting is not an emergency if the supply is shut off and the area is protected, but a heater with a leaking tank can release a lot of water quickly, damage floors and walls, and create an electrical hazard if it is electric. Keep the unit off and the supply closed until it has been inspected. Moving valuables away from the area and putting a drain pan or towels under the unit limits damage while you wait.
How to prevent leaks at the bottom of a water heater
- Flush the tank each year so sediment does not hold moisture against the bottom or damage the drain valve.
- Have the anode rod checked every few years and replaced when it is mostly gone.
- Install a drain pan with a drain line where a leak could damage finished space.
- Keep the relief valve discharge pipe clear and unobstructed.
- Check connections for drips or mineral crusting every few months.
The full list is in our annual water heater maintenance checklist.
Frequently asked questions
Why is my hot water heater leaking from the bottom?
The most common sources are the drain valve, a fitting at the top running down the side, the relief valve discharge, condensation or a corroded tank. Finding where the first drops start, with the unit dry and the supply shut off, tells you which.
Can a water heater leaking from the bottom be repaired?
If the source is a valve, fitting, gasket or drain, yes. If the tank shell is leaking, no. The tank must be replaced.
Is a leaking water heater dangerous?
It can be. Water near electrical connections is a shock hazard, a failing tank can release a lot of water, and a leaking gas unit can have other problems at the same time. Shut off power or gas and the cold water supply, and have it inspected promptly.
How much water leaking is an emergency?
Any steady flow, any pooling you cannot stop by shutting the supply, and any leak near electrical equipment is an emergency. Our emergency water heater repair line is open 24/7.
What does the leak look like when the tank has failed?
Typically rust-colored water or streaks at the seam or base, water that returns after fitting repairs, and a unit that is old. A technician can confirm it quickly.
We find and repair water heater leaks across Lake Stevens, including South Lake Stevens, Old Town and Lochsloy. See our water heater leak repair page for what a visit involves, and call any time, 24/7.