Why Is My Water Heater Leaking? (And How To Fix It)

water heater leaking

As homeowners, most of us expect our water heaters to reliably deliver hot water whenever we need it.

However, discovering a water heater that is leaking or dripping can quickly turn the convenience of on-demand hot water into a stressful nuisance. Even small, intermittent drips can rapidly escalate into more serious flooding if left unchecked.

The good news is that with some basic troubleshooting, the cause of most water heater leaks can be identified and fixed.

In this quick guide, we will arm you with insider knowledge on water heater leak troubleshooting so you can act swiftly and decisively if you ever notice water where it doesn’t belong.

What Causes a Leaking Water Heater?

Is your water heater currently leaking water? Chances are, you’d say yes if you are currently reading an article.

If you said yes, then the next thing would be to try to resolve the problem right away because nobody loves seeing the puddle of water the leaks create around the area where the heater is mounted.

So, what’s behind the leaks anyway? To know what, let’s take a look at some of the most common reasons:

Gradual Aging

Like any other appliance, water heaters are susceptible to deterioration over time due to gradual aging. Water heaters can typically function continuously without issues for up to 10 years. However, as they continue to age, they will eventually start showing signs of wear.

By the 10–15-year mark, an aging water heater without proper maintenance will almost certainly start leaking in some capacity. Whether it is the tank, valves, or pipe connections, the years of wear will have taken their toll.

Catching and patching leaks can extend the appliance’s life slightly, but typically a full replacement is required once major leaks occur. This is why it is important to be vigilant about maintenance and checkups especially when a water heater reaches later years of service.

Loose pipe connections

One common reason for water heater leaks is loose pipe connections. Every water heater has pipes connected at the cold-water inlet and the hot water outlet. These connections link the water lines that supply water throughout your home. But over time, the action of heating and cooling the steel piping and even general vibrations can cause the threaded connections to become loose.

Now when the inlet and outlet fittings become loose, small gaps open up between the metal components. The leaks you now notice coming from your water heater may come from the gaps at the loose joints. A loose connection may leak just a few drops first but as vibration further widens the gap between loose connections, steady dripping or even spraying water can occur.

Bad drain valve

Another potential cause of water leaks from a hot water heater is a bad drain valve. You might not know this, but all conventional tank-style heaters have a drain valve near the bottom of the unit. The drain valve looks like an outdoor hose bib but points straight down. The drain valve is used to empty water from the tank during maintenance tasks or repairs.

So how does the drain valve cause leaking? As you continually use the drain valve, the screw-on drain valve can wear out. Aside from wear, mineral deposits from the hot water can also cause buildup that impedes proper valve closure.

Just like the inlet and outlet pipe connections, when the drain valve degrades, gaps appear in seal surfaces. These small openings allow hot water to escape from the unit in dripping air streaming leaks if the valve no longer seals fully when closed.

Faulty T&P valve

Nearly all hot water heaters contain a temperature and pressure relief valve near the top of the unit. This special safety valve serves the purpose of releasing excess heat or water pressure from inside the tank before dangerous levels build up. The T&P valve discharges through a pipe pointed downwards to the floor.

Now, the relief valve has a lever that should only rise to vent water if the user sets the thermostat too high or other conditions elevate tank pressures. However, even when hot water temperatures remain safely below 120°F, a faulty T&P valve can still leak steadily.

How? You might wonder. Well, imperfections in the valve seat or seal surfaces can allow small amounts of water to constantly drip out under normal pressures.

High water pressure

The incoming water pressure from your home’s supply lines can contribute to leaks if it gets too high for the tank to handle safely.

Typical household water pressure can range anywhere from 30 psi (pounds per square inch) to 100 psi depending on your municipal infrastructure. Water heaters are built to withstand the normal pressures within this range during use.

However, consistent spikes over 80 psi start to overload the tank components and safety features. At those elevated pressures, seals can get pushed open leading to leaks at pipe connections and valves. The T&P (temperature and pressure) relief valve may also open to release excess heat and energy from the over-pressurized water.

Over time, excess pressures that are beyond system capacities can lead to uncontrolled water leaks and even possible tank failure down the road.

If you suspect high inlet pressures, you can check the psi at various faucets with a pressure gauge. If flows over 80 psi are recorded, consider installing a whole house pressure-reducing valve. This can be set to a safer 50-60 psi to protect appliances like water heaters from excessive inlet pressures coming from municipal water main lines.

Hard water

The mineral content in residential water supplies contributes to cracks and leaks in hot water heaters over time.

Water is said to be “hard” when it contains elevated levels of calcium, magnesium, and other dissolved solids. So as hot hard water contacts the inner tank surfaces, the mineral deposits accumulate in layers.

The rigid scale of the mineral buildup prevents the steel tank walls from properly expanding and contracting with temperature fluctuations during heating cycles. This forces the metal to crack around the hardened mineral accumulation sites. When that happens, it creates small fissures in the tank that allow water to escape through them as pressure and heat levels change.

Areas near the tank tops and bottoms experience the greatest temperature variances and are most prone to developing hard water cracks. The only remedy once the steel is compromised is to fully replace the leaking tank, along with addressing any insufficient water softening treatments to prevent rapid recurrence.

Note: The ideal hardness for a water heater is between 6 and 8 grains per gallon.

Cracks from expansion/contraction

The water inside your hot water tank goes through a lot of expansion and contraction as it gets heated up and then replaced. This happens even if you have soft or filtered water – it’s just natural with the heating process.

When water is heated, its volume grows over 20%. To put this into perspective, the amount of water itself gets about one-fifth bigger just going from a normal groundwater temperature to the 140°F needed for hot showers and washing.

On top of the heating expansion, many areas also have pretty big seasonal temperature changes in their groundwater – sometimes over 50°F difference between summer and winter! So the poor water tank has to deal with water swelling and shrinking all year round.

All that back-and-forth stretching stresses out the solid steel walls over time. After dealing with thousands of heating cycles, the steel starts to warp and bend just a tiny bit. This warping keeps worsening gradually until one day, a small crack punches through the surface.

Once a crack makes its way through the hot tank walls, quick fixes unfortunately don’t work well anymore. The constant expanding and contracting water pressure will find that crack and continue wearing it out. This means if your tank springs a leak due to temperature fatigue, you’ll likely need to replace the whole system to stop the leakage.

Anode Rod Corrosion

The anode rod is an important piece of your hot water heater that helps prevent the metal tank from rusting. It’s made of a reactive metal like aluminum, zinc, or magnesium.

The anode rod attracts damaging contaminants in the water instead of letting them reach the tank walls. It basically “sacrifices” itself by slowly eroding due to the contaminants sticking to it over time. This buys years of protection for the tank.

However, after many years, the anode rod erodes too much and can’t safeguard the tank walls anymore. Then three problems can occur:

  1. With no anode rod barrier, contaminants start attacking the metal tank walls directly. This quickens corrosion and rust on the inside of the tank, which eventually causes small leaks.
  2. Bits and pieces of the used-up anode rod break off and fall to the tank bottom as debris. Over several years, too much of this buildup can cause cracks in the base that leak water.
  3. The bare spot where the anode rod used to be also gets exposed to contaminants once the rod falls apart. Leaks can then spring at this location on the tank’s inner surface.

While a slowly wasting anode rod itself won’t directly cause a hot water heater leak, not swapping out a fully corroded one after 3-5 years can accelerate tank aging. Replacing rods on schedule is important to keep your water heater protected!

You can check the condition of your anode rod by draining some water from the tank and unscrewing the rod for inspection. If the rod is heavily corroded or covered in calcium deposits, you should replace it with a new one.

How to Tell If Water Heater Is Leaking

water heater drain valve leaking

Unless there’s a big hole in your water heater tank (the type that can’t be missed), the chances of finding out your water heater is leaking early enough are slim. One way to find out is by inspecting the water heater often but not everyone has the time to do that.

So if I can’t check my water heater often, what do I do? How can I tell if my water heater is leaking? If you thought that, then that was a very wise thought.

In this section, you’ll find telltale signs that let you know if your water heater has started leaking. Without further ado, let’s briefly look at them:

Decreased hot water temperature

One sign that your water heater may start leaking is a decrease in the temperature of hot water. As the tank or valves start to fail, hot water may not get as hot as it should be. You may notice your hot water is only lukewarm instead of reaching the typical 120°F or higher. Lower hot water temperatures show that your heater is not working properly and a leak may soon follow.

Rusty water

Rusty and discolored water coming from your hot water taps can indicate a problem with your water heater.

When corrosion occurs on the insides of your tank, rust particles can break free into the water supply. Brown, red, or yellow tainted water is usually a sign of rust inside the tank. Rust accumulation often precedes cracks and leaks.

Exterior rust

Take a look at the outer shell of your water heater. It can also provide clues of an impending leak.

As the internal components corrode, exterior rust spots may become visible, especially around openings. Check the water and gas lines as well as the burner units for any exterior rust on your heater.

Noises during operation

Sediment collection inside the tank can cause noises as the water heater runs. As hardened mineral deposits shift and expand with temperature changes, they can create cracking or popping sounds. Increased noise from a generally quiet water heater often means something is coming loose internally.

Water pooling around the tank

The most definite sign your hot water heater will leak is finding actual water pooling around the base of the tank. Small drips may indicate cracks in tank components that precede larger leaks. The source of tiny drips can be hard to locate but be aware pools of water are a warning. Address any water around your tank promptly before major flooding occurs.

How to Fix a Leaking Water Heater

water heater leaking

Now the moment you have been waiting for. In this part of the article, you’ll learn ways to troubleshoot (discover the source of) the leak and fix it.

Step 1: Confirm the leak is from the water heater

Before you dive into repairs, it’s important to confirm for certain that your water heater is the real culprit behind any water on the floor. Drips near – but not directly from – the tank can be tricky and mess with your diagnosis. Condensation is another thing that can mimic a leak when it evenly coats the tank exterior.

So how do you tell what’s really going on? Start by thoroughly cleaning up any wet areas around the tank. Keep an eye on things as the water heater runs through some heating cycles. See if new pools of water form at pipe joints, valves, or the drain pan underneath when heated up.

If the water heater stays dry during the heating process, it likely means that the leaks are happening somewhere else. Alternatively, if moisture develops evenly over the surface of the unit, it means that condensation has taken place – that is the water heater is very hot but the room it’s located in is cold – and condensation is not a cause for alarm.

Also check if appliances like your HVAC are dripping liquid onto the top of the water heater, faking leak symptoms. Hence, isolating the real leaking point will send your repair work in the right direction!

Step 2: Turn off the power and water supply

Once you confirm your water heater itself is leaking, the next vital step is powering everything down before attempting repairs.

For gas water heaters, locate the shut-off lever by the gas supply line. Turning this perpendicular to the pipe cuts off the combustion fuel. Electrically powered heaters instead have either an internal disconnect switch, an external power switch, or a dedicated shut-off circuit breaker at your home’s main electrical panel box. Flip the correct switch or breaker to OFF.

You’ll also want to stop the flowing water supply. There should be an isolation valve near where the cold inlet pipe meets the storage tank. Turning this fully off stops new water from entering the system. If you can’t find this valve, using the main water shut-off for your whole home is the way to go.

In addition to that, also turn off the cold and hot water supply for your unit. To shut them off look for two valves on your hot water heater, one for the hot water and the other for the cold water. Most of the time, they are color-coded, the blue mark represents the cold water while the red mark, the hot water. Some water heaters may have a single lever that controls both the cold and hot water valves, instead of two separate valves.

After turning them off, you should drain the water heater. After draining, wait for the water heater to cool down (it could take a few hours) before proceeding with the repairs. Also, open the hot water faucet in your home to relieve the pressure in the tank before draining.

It’s important to do all these because you don’t want to mix live electricity or gas burner flames with flowing water during repairs – the result is dangerous as it could lead to electrocution or explosion.

Step 3: Locate the source of the leak

With the energy sources deactivated, your investigation should turn to pinpointing exactly where the water is escaping from. The troubleshooting order begins by examining the following common leak points starting at the top and working downward.

Hot Water Heater Leaking from Top – tighten connections

Any water trails you find stemming from the metal pipes or flexible lines affixed to the tank top likely indicate loose fittings or faulty gasket seals.

In this situation, you should check if the water inlet and outlet connections at the hot and cold pipes have not vibrated loose over time. If they have, manually tighten loose joints with channel-locking pliers or an adjustable pipe wrench to close minor gaps.

More severely loose pipes may need sealant compounds added or be fully tightened once empty. Additionally, you may have to replace any gaskets showing cracking or dissolution if you use an electric water heater.

Hot Water Heater Leaking from Side – replace the T&P valve

If water leaks halfway down the tank side, it may point toward problems with the T&P relief valve. This emergency pressure release port remains normally closed but can leak over time if the sealing surfaces degrade or the valve sticks partially open.

To fix that, you can open and close the valve several times. But if the relief valve steadily drips, then it requires immediate replacement using proper pipe thread sealants.

When choosing replacement parts, make sure to select a replacement T&P valve rated for the tank size and heating capacity.

Hot Water Heater Leaking from Side/Bottom – tighten the drain valve

If you notice a puddle on the floor under the middle of your hot water tank, the likely culprit is a worn-out drain valve. The drain valve lets plumbers access the tank interior to flush out sediment when servicing the unit. But after years of use, it can fail to fully seal closed again after being opened.

Try gently tightening the valve base with a wrench to see if the dripping stops, being careful not to overtighten. If water still trickles out even when the handle is fully closed, the entire valve probably needs to be replaced in order to restore a watertight seal on the tank underside.

Note: There’s also the chance of your water temperature being set too high. Before replacing the valve, make sure that your water temperature is not set above 120°F (49°C).

Water Heater Leaking from Tank Itself – replace the water heater

The worst case is when water seems to weep directly through the steel lower tank itself with no particular valve or seam source. This means extensive corrosion, hard water damage, or one too many heating cycles has caused inner wall cracks.

Unfortunately, structural tank degradation cannot be repaired – sealing up serious metal vessel cracks is virtually impossible. If leaks come directly from the body of the tank itself and not valves/pipes, complete water heater replacement is needed in this end-of-life situation.

Leaving interior tank wall cracks unaddressed leads to bigger failures, so have a technician assess unexplained seepage from the equipment body as soon as possible.

Step 4: Clean up spilled water

Before fixing any leaks, it’s important to fully wipe up and dry any spilled water on the floor or surroundings. Even small drips can slowly release hot, mineral-laden liquid over time. Letting those pools sit risks slips and falls, wood warping, mold growth in soaked insulation, and water stains.

Stay on top of mopping up or vacuuming damp areas during your troubleshooting too. Catching a tricky leak might take a few heating cycles to pinpoint. Repeatedly absorbing escaped water prevents little puddles from becoming big repair jobs if unchecked seepage damages things long-term. Always assume that the leak isn’t fully fixed until everything stays nice and dry.

Step 5: Call a professional if needed

While simple fixes like tightening pipes or replacing a drain valve are doable yourself, know when to call a professional technician. Anything involving gas lines, electrical risks, heavy equipment, or complex valves requires specialized skills and gear. Well-meaning but improperly executed repairs can result in severe floods, property damage, and even personal harm.

How Do I Prevent My Water Heater From Leaking?

Now you know how to fix a leaky water heater, it’s now time to learn about the preventive measures you should carry out periodically to prevent your water heater from leaking in the future.

Annual maintenance

Scheduling yearly checkups lets technicians find and fix small issues before they turn into big leaks or failures. During maintenance visits, they thoroughly inspect all valves, pipe connectors, seals, internal rods, insulation, exhaust components, and the tank surface. Any drips, corrosion, mineral buildup, or broken parts get replaced to keep things working safely. Professionals also drain the tank to flush sediment.

Flush sediment from the tank

Letting sediment accumulate leads to pitting and corrosion-promoting leaks. Annual flushing removes scale deposits and extends tank life.

To flush, attach a garden hose to the tank drain valve and route it to a drain or outdoors. Open the drain valve and run water through for 5 minutes until the discharge runs clear. This cleans accumulated solids without using harsh chemicals in DIY attempts. Always close valves gently to prevent seat damage leading to leaks.

Replace anode rod

The anode rod attracts damaging sediment to protect the tank but wears out itself every 2-4 years in the process. Letting it fully dissolve removes the tank’s shield, allowing corrosion and pits to form. Regularly swapping rods maintains the tank’s inner protection. And make sure replacement rod materials match tank types to avoid rapid corrosion.

Set proper temperature

Keeping your tank water above 120°F increases expansion stress on seams and the T&P relief valve. At higher temperatures like 140°F, the 7% growth in water volume can strain components to the breaking point over years of heating cycles.

Keep settings moderately low to prevent pressure issues and slow normal wear & tear. Use insulation or tempering valves at fixtures to balance delivery volumes with safe heating setpoints preventing scalds.

Insulate pipes

Exposed inlet and outlet piping lose considerable heat during transport. Ensuring full-wall thickness foam insulation containment on hot water lines reduces thermal losses and keeps pipes warmer.

Higher transport temperatures minimize precipitation of scale inside pipes that can lead to supply-side corrosion and leaks over time. Insulation also keeps electrical elements and gas flames firing less often by trapping heat.

Replace tank before 15 years

Even with great care, commercial water heaters reliably last about 12-15 years before age catches up. Water minerals take an unavoidable toll on critical seals, valves, and safety components over time. Replacing tanks before hitting the 15-year mark ensures peak efficiency and safety with modern designs. New insulation also regains temperature retention.


Dealing with a leaky water heater can be stressful and confusing – but now you’re armed with the knowledge to get to the bottom of the issue.

By methodically troubleshooting where water is coming from and why, you can determine whether some simple pipe tightening is needed or if major components are failing internally. Don’t panic at the first sight of droplets or ambiguity – just go step by step using proper safety precautions.

And remember preventative care is key for maximizing your water heater’s lifespan without leaks ruining your day in the future. With annual draining, replacing worn parts before they fail, and keeping settings at safe levels, your hot water system will stay leak-free for over a decade.

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