Although modern units have numerous features to improve safety and efficiency, storage tank water heaters are still relatively straightforward appliances. Water heater designs are self-circulating, which means cold water enters near the bottom of the tank using a dip tube. Hot water rises to the top of the tank, and the increased pressure circulates it to your fixtures.

Unless your tank is leaking due to corrosion or damage, there are typically only three locations you may experience drips: the relief valve, the drain valve, or inlet/outlet connections. While some water dripping from the relief valve is normal, excessive water can be an issue. Understanding why your heater is losing water is the first step to repairing the problem.

Cause #1: Normal Water Expansion

Water pressure inside your tank will increase with temperature. All storage tank heaters include a relief valve to keep your water heater from failing catastrophically (and violently). This valve releases some water when the pressure in the tank increases too much, and you might notice a few drops once or twice per day.

If you see significant releases from the relief valve, you may have your temperature set too high. Other issues include excessive water pressure, which could be due to city supply problems or a water meter valve that's set too high. If you have excessive dripping from your tank, you should have a plumber evaluate the situation. An expansion tank may also help to resolve water pressure fluctuations.

Cause #2: Failing Valves

Both the relief valve and the drain valve can fail, allowing them to release water when they shouldn't. If you notice dripping from the drain valve, start by tightening it by hand. If it's still leaking, the valve is most likely faulty, and you'll need to replace it. In the meantime, make sure you place a container below the valve to catch any excess water.

The pressure relief valve can also fail. The valve should rarely run for long, so a continuous stream of water is a good sign that you'll need a replacement. You can also slightly lift the lever (avoid pulling it far enough to lock) to release water. If the lever sticks or doesn't release water, that's another sure sign that you need a replacement.

Cause #3: Inlet/Outlet Pipe Leaks

Your water heater should have two pipes at the top – one for cold water and one for hot water. Either pipe can leak at the fittings or the valve. If you notice water on the floor near your water heater, make sure it isn't dripping down from the top of the unit. Check for signs of moisture around both pipes, as this can be a good indication that you've got a leaky valve or fitting.

If you don't see any obvious source for a leak, you'll need to contact a plumber for further diagnosis. Leaks from unknown sources may be due to a cracked or corroded tank, in which case you should usually let a professional suggest the best course of action. Contact someone in your area for water heater installation services.