If your water heater relief valve is leaking you need to call a service technician to properly troubleshoot and repair the problem. The main indication that the water heater is leaking from the relief valve is a puddle of water right below the valve pipe. This is a serious issue that must be addressed immediately.
When the water heater pressure relief valve is leaking there is too much pressure building up in your system or that you have a faulty pressure relief valve.
The water heater release valve is a critical part of the safety of your water heater and should be treated with great respect. If the pressure release valve is malfunctioning it could lead to a dangerous build up of pressure in your system. Too much pressure in the system will eventually lead to a catastrophic failure which could ultimately result in harm to you or your family. Any problems with the pressure relief valve should be fixed by a licensed professional who can accurately diagnose what is causing the problem and fix it properly.
There are, however, other reasons why the pressure relief valve could be releasing water. For instance, if you have the water temperature set too high on your thermostat, the water heater can begin to create steam. Steam creates a high pressure in your water heater tank and the pressure release valve may open to release the steam. This can be quickly and easily remedied by turning down the water temperature on your thermostat.
Another possible culprit is the build up of sediment at the bottom of the water heater tank. This sediment build up causes the water to super heat rapidly and is generally accompanied by loud noise coming from the water heater. Flushing the water heater system should help to eliminate this problem.