The temperature and pressure relief valve is designed to release water if there's too much pressure inside the tank, or if the water gets too hot. The t/p valve is equipped with a discharge tube that runs from the valve to the floor. The tube is in place to make sure that any water that leaks from the valve is safely directed downwards, towards the floor, rather than outwards where it could be harmful.
If you notice a puddle of water at the bottom of your hot water tank, check the inside of the discharge tube for any moisture. If you find water, the problem is most likely the temperature and pressure relief valve.
The valve is either faulty or there is too much pressure in the tank. This problem is usually fixable by either replacing the valve or calling a plumber to deal with the internal pressure problem.
Every water heater has a drain valve at the bottom of the tank. The drain valve is used to drain the tank. It should be drained on a regular basis to remove the sediment that collects within the internal tank. If the sediment isn't drained, it will eventually cause damage to the inside of the tank.
If you notice water pooling around the bottom of your tank you may have a drain valve leak. There are 2 causes to a drain valve leak:
A faulty drain valve will need to be replaced, or you may be able to use a brass garden hose cap to stop the leak until you're able to swap it out with a new one.
If you notice water seeping out of the edges of the valve, in most cases the valve isn't water tight and it's simply leaking. Replacing the drain valve will usually solve the problem.
Most leaks come from the hot water tank itself. If the tank is leaking, there is an internal problem, and likely one of the components has sprung a leak, causing water to slowly leak out and pool at the bottom of the tank.
Usually, the cause of this is sediment build-up inside the tank. If this sediment is left long enough it will begin to crack and rust the steel tank, eventually leading to a leak.
A leak from the tank itself almost always means the water heater will need to be replaced. In this scenario, you can either contact a professional plumber to investigate further, or you can simply purchase a new water heater.
Now that you've located the leak, the next step is to turn off the water and power to the water heater, this will help prevent further water damage.
Refer to your emergency shutdown procedure sticker located on your water heater. If your water heater does not have this sticker, follow these steps:
Depending on where your leak was, and your comfort level, you may choose to do the repairs yourself, or contact a plumber to make the repairs for you.
If the leak was originating from the temperature/pressure valve, or the drain valve, it's highly likely that your water heater can be repaired.
However, if you find that your internal tank is leaking, you'll most likely be buying a new water heater