If you find a pool of water underneath your water heater it could be a serious problem. A leak from the bottom of the tank is the most common place to find a leak, and is usually the most cause for concern. What exactly could be the cause? Here is a step-by-step guide to troubleshoot and resolve your leaking water heater:Step 1: Find the LeakWater Heater Leaking from Bottom Cause #1: A leak from the temperature and pressure relief valveThe temperature and pressure relief valve is designed to release water if there is 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. This 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 there is 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 any water, the problem is likely the temperature and pressure relief valve. Either there is too much pressure in the tank or the valve is faulty. This problem is usually fixable by either replacing the valve or calling a plumber to deal with the internal pressure problem.Water Heater Leaking from Bottom Cause #2: A leak from the drain valveEvery water heater has a drain valve at the bottom of the tank. The drain valve is used when draining the tank to remove sediment that builds up and eventually causes damage to the inside of your tank. If the valve is faulty, water will begin to leak and pool at the bottom of the tank. If the valve isn’t water tight, water may also start to seep out of the edges of the valve. A leaky drain valve is very fixable. Replacing the drain valve will usually solve the problem. If the valve is faulty, you can screw on a brass garden hose cap to stop the leak until you are able to have it replaced.Water Heater Leaking from Bottom Cause #3: A leak from the tankMost 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 tank, eventually leading to a leak.A leak from the tank itself almost always means the water heater needs 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.If you find that your leak is coming from somewhere else, check out a more extensive article which will help you troubleshoot. Water Heater Leaking from Bottom: How to prevent itPerforming regular water heater maintenance will help extend the life of your water heater. Flushing your water heater and checking the anode rod once a year will help prevent sediment build-up, which will in turn, extend the life of your water heater.Step 2: Prevent Further Water DamageNow that you have located the leak, the next step is to turn off the water and power to the water heater, which 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:Turn Off the PowerElectric Water Heater – Turn OFF the breaker for the water heater at the main electrical panel. Most water heaters use a 240 volt dedicated circuit breaker, which means that no other appliances will be on the same breaker.Gas Water Heater – Find the on/off dial, located on the side of the water heater near the bottom. Turn the dial to the OFF position.Turn Off the Water SupplyFind the lever or dial located on the water supply inlet.The water supply inlet is located at the top of your water heater. This is where the water enters the tank to be heated.To turn off the water supply, you simply turn the dial clockwise, or turn the lever to the closed position (usually parallel to the pipe).This video will guide you thru troubleshooting your leak, as well as how to turn off your water heater.Step 3: Decide What to Do NextDepending 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 is highly likely that your water heater can be repaired.However, if you find that your tank is leaking, there is a good chance that you will need to purchase a new water heater.Check out our buying guide resources to help you make an informed decision:Water Heater Buyer’s GuideWater Heater Buying Guide: Storage TypeWater Heater Buying Guide: Fuel SourceIt is important to keep in mind that water heaters have a life expectancy of up to 10 years, depending on the fuel source. If your water heater is nearing old age, or experiences any of these issues, regardless of the source of the leak, it may be more cost effective to purchase a new one.