Hot water system leaking from the bottom: what it means

First, make it safe

If there's a lot of water, turn off the cold water valve going into the system and switch off its power or gas. Our guide on how to turn off a hot water system shows you how. Don't touch the relief valve or drain the tank, because the water can be hotter than 60°C.

Find where the water is coming from

Dry the area with a towel and watch where the water reappears. It usually comes from one of these:

The tank itself

Water seeping from the base, rust streaks down the casing or a steady pool that comes back however often you dry it usually means the inner tank has corroded through. A tank can't be repaired, so it needs replacing. This is the most serious cause, because a corroded tank can get worse quickly.

The relief valve drain

The pressure and temperature relief valve has a drain pipe that often ends near the base of the system. A small discharge while the tank is heating can be normal. A constant drip or steady flow usually means a worn valve or high water pressure, which are repairs.

The expansion control valve

Some systems have an expansion control valve on the cold water side, with its own drain. If it's dripping constantly, the valve may be worn or the water pressure may be too high.

A fitting or valve dripping down

A leaking joint, isolation valve or tempering valve above the tank can run down the outside and look like a tank leak. Check the pipes and valves above the wet spot. These are usually quick repairs.

Condensation from a heat pump

Heat pumps pull heat from the air, and on humid days that makes condensation, which drains out near the base. Clear water dripping from a heat pump's drain while it's running is normal. Water from the tank itself is not.

Repair or replace?

If the water is coming from the tank body, it's a replacement, and we can usually do it the same day. If it's coming from a valve, fitting or drain, it's usually a repair. See leaking hot water systems for how we handle each one.