A leaking water heater is more than an inconvenience because it both limits the availability of hot water and causes water damage.
Water Heater Leak Causes
There are three main areas prone to leaking on the average tank-style water heater— the inlet and outlet lines, the overflow drain, and the base of the heater. Inlet and outlet lines tend to leak because the fittings are either loose or worn. The overflow drain, which is located on top of the heater, is made to leak in the event temperature and pressure builds up to a dangerous level inside the tank.
A leak at the bottom of the tank is typically due to the drain line being left open—which is an easy fix—or from rust and corrosion to the tank itself. Hard water sedimentation settles at the bottom of the tank. This sediment can increase the chances of corrosion and lead to a breach in the tank itself.
Symptoms of Leaks
Leaks are sometimes obvious. Larger leaks or a pressure overflow will lead to a large puddle of water around the heater and you may end up with absolutely no hot water in the house (or the amount of available hot water will be greatly reduced). A quick visual inspection will reveal the leak.
Not all leaks are immediately obvious, though. A slow leak from a loose-fitting, slightly open drain or a developing crack in the tank may only let out small amounts of moisture. If you have a drain pan beneath your water heater, you may not even see water on the ground. Periodically check the drain pan for moisture. It is also a good idea to visually inspect the valves and drains for obvious wear or moisture on the surface that indicates water is escaping.
Repair Vs. Replacement
Whether to repair or replace depends on the location and severity of the leak. If the issue is with the inlet or outlet fittings, or even with damage to the hoses themselves, replacement is a simple and inexpensive repair that will give your heater many more years of life. If the tank is damaged or corroded, though, replacement is the only option because patching is simply not a dependable fix.
Overflow drain leaks can be due to a variety of reasons. In some cases the issue is the thermostat, so a simple adjustment or thermostat replacement is all that is necessary. In other cases, sedimentation in the tank can be the problem so you just need to have the tank flushed. Issues with the elements or the electric system, though, may mean it is time to install a new water heater.
Contact a water heater service if you suspect a leak on your water heater.