Why is my water heater leaking from the bottom?

AllClear 10:05 pm

Why is my water heater leaking from the bottom?

Why is my water heater leaking from the bottom? – That’s the type of question that is usually said with a groan and a grimace. Property owners dread moments like this, brace themselves, and start to mentally check their bank account balances. While a water heater leak can indicate a serious issue – especially at the bottom of the tank – it isn’t necessarily a death sentence for your heater.

Why is my water heater leaking from the bottom- water heater graveyard

Immediate action may be needed to protect your home. We will get to diagnosis in a minute, but before we do, let’s look at immediate steps to take.

What to do when you have a leak from the bottom of your water heater – Immediate Steps

Regardless of what is causing the leak, priority one is protecting you and your home. Especially if your water heater is located inside, you’ll want to make sure to limit water damage. Let’s avoid a costly insurance claim!

First, turn off the power.

For an electric water heater, look for the breaker on the main electrical panel. Hopefully, this is labeled. Most of the time this will be a dedicated 240V breaker. Because it is a dedicated breaker, it shouldn’t turn off anything else. Turn this to the OFF position.

Why is my water heater leaking from the bottom

For a gas water heater, look for an on/off dial or switch on the heater itself. Usually located toward the bottom of the heater, turn this into the OFF position.

Second, turn off the water supply.

The water heater will just keep refilling itself unless you stop the supply. This means an endless amount of water will continue to run until the supply is off. (Exactly why we recommend turning off the water to your home when going on vacation!)

There should be a lever or valve toward the top of the water heater. This is the water supply inlet and is exactly what it sounds like – how water gets into the heater. Remember “righty-tighty” to close the valve!

It is not strictly necessary to turn off the gas on a gas water heater. However, some people feel more comfortable adding this step. To turn the gas off, look for a smaller lever towards the bottom of the heater. The handle might be red, blue, or yellow. Turn this to the OFF position.

Why is my water heater leaking from the bottom - gushing water

These steps keep the water from flowing in your house like the rivers of Egypt. However, you still have a tank full of water.

If the leak is very aggressive and already filling the overflow pan, tart bleeding the tank of remaining water. This is most easily done with a garden hose attached to the drain valve. Look for the drain valve at the bottom of the tank. It will look similar to the hose bib on the side of your house. This may actually be where the leak is coming from, but should still function for this purpose.

Why is my water heater leaking from the bottom - drain with garden hose

Attach the hose to the valve and run it either outside or to a nearby drain and open the valve (“lefty-loosey”). This will keep the remaining 30-50 gallons in your water heater from leaking all over the area where the water heater is stored.

If you absolutely can’t figure out how to do this or don’t have a bucket or hose, turn on all of the hot water taps in your house. The tank will eventually drain.

Why is my water heater leaking from the bottom - drain hot water

Find the Source of the Leak

Now that the leak is under control and there is less concern about damage to your home, we can start to figure out where this water heater leak is coming from. Before you call a licensed plumber, try to self-diagnose the repair. The steps below will help estimate the severity of the issue and give you something to talk about with your plumber.

Why is my water heater leaking from the bottom of the tank?

Bad news first. If the water heater is leaking from the bottom of the tank itself there is no getting around a water heater replacement. The tank has rusted out, likely due to sediment build-up. There is no way to repair the tank without replacing the entire thing. The leak will start out small — likely a pinhead but tank pressure will force that leak to get bigger and bigger. There isn’t a way to ease into that news, so there you have it.

Why is my water heater leaking from the bottom - rusted out tank

If a tank leak is your issue, immediately turn off the water heater supply and call a licensed plumber. That tank is going to keep leaking, so don’t keep feeding it water! Use the steps above in the “immediate steps” section to help with this.

Why is my water heater leaking from the bottom drain valve?

Every tank-style water heater has a drain valve at the bottom. These are intended for use during maintenance and replacement of the water heater. Sometimes, the drain valve can become loose or fail.

Why is my water heater leaking from the bottom - drain valve

If the drain valve is leaking, try tightening it by hand first. It is possible that the valve was just knocked loose. If hand-tightening doesn’t stop the drip, or if the drip is coming from the base of valve rather than the nozzle, it needs replacing.

Never use a tool to close this valve. It is designed to close by hand. Continued dripping, once tightly closed, indicates something is wrong. You may make a bad situation worse by over-tightening and could even break the valve off completely!

Very handy folks may feel comfortable replacing the drain valve on their own. Once the tank is drained, a little Teflon tape, a wrench, and elbow grease is all it takes. Drain valves are sold at most home improvement stores.

If you can’t get to the repair immediately or if the plumber is going to be a while, you can stop a drip from the nozzle by putting a simple garden hose head on it. It’ll look a bit silly, but stops the drip pan from overflowing before the repair is done!

Why is my water heater leaking from the bottom at a tube?

This tube is connected to the Temperature and Pressure Relief Valve, also known as a T&P Valve. The valve itself is usually towards the top of the water heater, but a tube may be attached running to the bottom pan of the heater.

Why is my water heater leaking from the bottom - T&P Valve

T&P valves “go off” when either the temperature or the pressure in the tank gets too high. This neat little piece of technology is actually what keeps your water heater from shooting off like a rocket when things get too hot. So, we obviously want that to stay in good working order.

Why is my water heater leaking from the bottom - rocket

That’s the crux of the problem – if the T&P valve is releasing, it might mean that the valve is doing its job or it might be faulty. It could also mean that the pressure in your house is too high (a common problem here in the Upstate) or it might mean the temperature is too high on the heater itself.

You never want to block, close, or otherwise disable a Temperature and Pressure Valve for reasons listed above. This valve should always point down so you don’t accidentally get hot water to the face. They can go off without warning and release very hot water.

If you have a Pressure Regulating Valve (PRV) on your house, check to make sure it is set correctly. If you do not, checking your water pressure is a good start. A water pressure gauge can be purchased inexpensively.

Water pressure higher than 75 PSI is cause for concern. For the overall health of your plumbing, this should be addressed by installing or fixing a PRV.

Next, check is the temperature settings on your water heater.

Why is my water heater leaking from the bottom - water temperature

The factory recommended settings are your best bet for water heaters. Too high or too low, each come with a unique set of risks.

Too high is an obvious safety concern. Scalding can happen quickly and is extremely risky for small children and the elderly.

Sometimes the configuration of your plumbing requires a slightly higher temperature, due to thermal loss. Meaning that water cools down quickly on the way to the fixtures, requiring a higher starting temperature. If your water heater doesn’t deliver hot enough water to fixtures when at the factory settings, talk to your plumber about how you can improve the efficiency of your plumbing.

Never set your water heater for lower than the factory recommended temperature settings. This is very dangerous and can lead to the development of Legionnaires Disease in your water. Very dangerous and not something you want to tangle with. Trust us.

If your water heater is turned up to a temperature higher than the recommended factory setting (usually 120°F) and you want to keep it there, it is worth experimenting with that setting before calling a plumber. It may very well be causing your T&P Valve blow off.

If the water pressure or heat isn’t too high, the T&P valve is faulty. You will want it replaced immediately. Luckily this is a minor repair typically completed in about an hour. The parts cost is also minimal. All-in-all, not a bad ordeal.

How do I prevent my water heater leaking from the bottom?

Preventing a leak at the bottom of your water heater isn’t always easy. Eventually, age will ravage your water heater one way or another. The life expectancy of a water heater is typically seven – twelve years. Keeping up with regular maintenance on your heater is a good way to ensure you get the longest use of the appliance.

Keep in mind that a yearly draining of your water heater and checking of the anode rod can extend the life of your water heater in several ways, not the least of which is preventing the rust which causes tanks to fail.

This is a fairly simple process, which includes unscrewing the anode rod from the top of the tank. Check the level of build-up on that rod. Replace it once it starts looking like an artifact from the Titanic.

Why is my water heater leaking from the bottom - anode rod

Draining the heater is as simple as attaching a hose to the drain valve or placing a bucket underneath the open valve. The whole tank doesn’t need draining though. Watch the water and turn off the drain valve once it is running clear. The purpose of a yearly draining is just to get that sediment out, which all sits in the bottom of the tank.

The best part about clearing out sediment periodically is that you gain more hot water! This is something to keep in mind if you have noticed that your hot water isn’t lasting as long as it used to. Sediment and mineral deposit build-up actually take up space in your water heater meaning that your 30-gallon tank might actually only have 20 gallons of water in it!

Other than regular water heater tank maintenance, water pressure and tank temperature are the two things to keep an eye on. The hotter the water and higher the pressure, the more wear and tear you are putting on the tank and your other plumbing fixtures and pipes. Just like when you drive a car aggressively, it may shorten the lifespan of the product.

Why is my water heater leaking from the bottom

Recap – Why is my water heater leaking from the bottom?

  1. Stop the damage and prevent more water from going to waste by turning off the heater and possibly draining it.
  2. Figure out if the problem is the tank, the T/P valve, or the drain valve.
  3. Decide if you can attempt the repair yourself.

A note on that last step …

Why is my water heater leaking from the bottom … and can I fix it myself?

A drain valve is relatively easy to fix on your own. It’s not especially fun and will probably eat up your afternoon, but it is doable.

A T&P valve is very important for the protection of your home and safety of operating a water heater. While it is possible to repair on your own, there may be serious consequences to a bad repair. It is recommended that a licensed plumber complete this repair.

Replacing an entire water heater is always something that a licensed plumber should complete. There are very real safety and property concerns that make a DIY job risky. It is highly recommended that you call a licensed plumber for a water heater replacement.


In Greenville and Anderson Counties, All Clear Plumbing would be happy to help you repair or replace your leaking water heater. Just call us at 864-979-7059 24/7/365 to speak to our friendly and knowledgeable staff.

Article Author: Anja Smith

Managing Partner

Anja Smith is the author behind the All Clear Plumbing blog. She also writes regularly for Plumber Magazine, TradeBizToolbox.com, and on Medium