Why is My Hot Water Heater Leaking?

I answered this question a couple of times over this weekend on 2 different forums and in the process realized how few people really know what the basics of a hot water heater are as well as the many things that can go wrong. In reality a hot water heater is made to last for many years and shouldn't leak as far as the tank is concerned. One forum questioner stated that his water heater looked new so he couldn't understand why it would leak. What you see of your heater is just a protective shell which holds insulation around the actual tank which you can not see. If a hot water heater is safely and dryly stored inside it should look new. What would cause it to age?


As I said most tanks are made to last for many years and leaks are rare early on. Instead of a leak it is more frequently the T&P (temperature and pressure relief valve) doing its job. This valve is installed to avoid an explosion of the tank if it overheats. By code in most areas the T&P valve should be piped out of the house for drainage outside so that the water blown out will not damage the house. I have seen some installations where the tank was in a location in the house where a drain line was not easily installed and a simple pipe down the side of the heater carried the overflow down to a catch pan under the tank. In some sloppy careless installations this pipe just runs out onto the floor which, of course, then looks like a leak and obviously can cause some major damage to the home if not caught soon enough.

Regardless there is still a problem if the valve discharges. It can be a faulty valve, which should be replaced if it every time it goes off, but usually is caused by the tank overheating. Overheating can be caused by a faulty thermostat or in the case of an electric heater can be caused by a heating element overheating in the process of burning out. The fix for these problems is replacement of the offending part.

If a tank is really leaking it is usually because it has corroded or rusted out or because the anode in the bottom of the tank has corroded and is leaking. Either way the entire water heater will need to be replaced. If replacing your hot water heater, it's a perfect time to consider a more efficient way to heat water. There are many alternatives today. The best, in my opinion would be to install one of the new generation of tankless, instant hot water systems. Although these are more expensive, initially, the money saved in heating costs repays this initial expense quickly. Another choice can be solar collector systems which pipe water through collector cells and store it for later use. If nothing else shop wisely when replacing your existing hot water heater to get the most efficient model available.