Most conventional homes are fitted with a water heater and are used, in one way or another, by every member of the household. However, it is not uncommon for these large appliances to be neglected, and their maintenance forgotten.

A leaking water heater is dangerous. Leaks can occur when a water heater is not maintained, which can be costly and damaging to your home, depending on where the water heater is located. In addition, it could lead to a build-up in pressure, which could cause a fire or even an explosion.

Let’s take a look at how water heaters work and what the common causes are for leakages. We’ll also explore the dangers of leakages and what can be done to prevent them.

How Do Water Heaters Work?

Though they may differ slightly around the world, the vast majority of water heaters use a tank and follow the same basic steps in order to heat your water:

  1. Cold water enters from the bottom of the tank from an outside pipe.
  2. The water is heated inside the tank, either from a gas flame below, or an internal electrical element.
  3. Hot water rises to the top, leaving the cold water in the bottom.
  4. When hot water is needed in the home, it gets pumped out of the tank from the top.
  5. As the water level drops, more cold water is brought in to refill the tank.

It is a relatively simple system, and your water heater gets used many times throughout the day. Whether from showering or doing the dishes, your water heater will be running for an average of three hours a day. Of course, that number changes depending on the number of people in the house. The more people showering, the more hot water is pulled from the tank, and the more cold water it needs to heat up.

Even though this appliance is used daily by everyone in a household, it is often left to run without much-needed maintenance. Without the proper maintenance, you could be looking at leakages that are costly and dangerous.

What Causes a Water Heater to Leak?

Most leaks in a water heater will be coming from the bottom and there are three primary causes for a leak.

Drain Valve

All water heaters are fitted with a drain valve. These are used to drain the tank in the event it needs to be fixed or moved, as well as draining any build-up of sediment from the bottom of the tank.

If you are maintaining your water heater, you should be draining and removing sediment at least once or twice a year. But much like any other valve, the drain valve can wear out over time, causing the tank to leak.

A leak in the drain valve suggests that it is no longer watertight. It could be something as simple as the valve not being closed properly. However, if you still notice a leak after you tighten the valve, it is important to get the valve replaced as soon as possible. You can purchase the part yourself, but it is recommended to call a plumber for installation.

Temperature & Pressure Relief Valve

A temperature and pressure relief valve is designed to release pressure from the tank in the event the water gets too hot, or there is too much pressure inside. Too much pressure inside a tank can potentially cause an explosion, as proved by the MythBusters in the video below:

As the water inside the tank is heated, it expands, causing pressure to build up. When the T&P valve senses excess pressure, it opens up, releasing the build-up of pressure. Similarly, should the T&P valve sense that the water is too hot, it will open and release some of the hot water. In doing so, cold water is pumped in from below, reducing the overall temperature inside the tank and reducing the pressure within.

A T&P valve is usually fitted with a tube that guides discharge out of the tank and is the most common place to check for a leak. A leak here indicates a faulty valve or too much pressure inside the tank.

Much like the drain valve, the T&P valve should be tested at least once a year and when working correctly, it should be dry. Due to the build-up of residue, it is recommended to replace the valve every few years. If you notice a leak, call a professional to inspect the valve.

The Water Tank

A single-family home will typically have a water heater with a capacity to store anywhere from 20 to 80 gallons of hot water. In Europe, tanks are usually made of either copper or stainless steel. In the United States, it is more common to find carbon-steel tanks. These tanks are often lined with vitreous enamel to protect against erosion.

However, even with a coating, many tanks are subject to erosion over time. This is often caused by a build-up of sediment at the bottom of the tank. As the water is heated and reheated within the tank, sediment will start to form on the bottom. Over time, as more sediment spreads, your tank will have to work harder in order to heat the water. This strain can cause the steel to become brittle and eventually crack.

Rust can also be found in the tank and on the pipes of your water heater. The trouble is, it can be difficult to tell where the rust is. You can see evidence of rust in the water and near the valves. Unfortunately, you cannot prevent rust. It is a natural outcome of constant use. However, regular maintenance and replacing your water heater before it expires can help to prevent leakages.

What to Do if You Notice a Leak

A few things will alert you to a potential leak in your water heater:

  • Loss of pressure through fixtures in the house
  • Dripping water from the T&P valve
  • Water pooling under the tank

Your first step should always be to turn off the power to the water heater and shut off the water. This way, you can safely inspect the unit to determine where the leak is coming from. If you are keeping up with regular maintenance, you should be able to catch a leak in its early stage, before it can cause too much damage.

Should you determine that the leak is coming from a valve, it is recommended to call a plumber and have them replace the faulty valve. A poorly replaced valve will cause more damage and leakage, and it is far safer to leave the installation to the professionals. Hopefully, this will be a quick fix and your water heater will last a few more years.

However, if you think the leak is coming from the tank itself, the only real option is to have the tank replaced. You cannot fix a rust issue without cutting away the affected steel. This would be too costly and difficult to do. Have a plumber confirm the issue and then look into getting a new tank.

Related: Should You Turn Off Your Water Heater if the Water Is Off?

Water Heater Alternatives to Avoid Leakages

As stated above, the vast majority of leakages are due to issues in and around the tank. Luckily, there are some other options.

Tankless Water Heater

As the name suggests, this option avoids issues of leakages by removing the tank from the equation. By removing the tank, the units are far more compact and essentially have an endless supply of hot water.

A water heating tank has a limited capacity and requires time to reheat the water. In contrast, the tankless heaters heat the water on demand, allowing for more hot water to be available when needed. Water is pumped in and heated by coils inside the unit, rather than storing hot water all day long. This makes them very energy efficient and a great choice for a family home.

Of course, these units also require regular maintenance. Much like your dishwasher, tankless water heaters need to be cleaned to remove mineral scale and avoid corrosion.

Hybrid Water Heater

This option is somewhere in between the tankless and common water heater tanks. Water is still kept in a tank, but rather than working to keep the tank hot all the time, the heat pump hybrid only heats the water when it is needed.

Better for use in warmer climates, the hybrid water heater pulls warmth from the air and ground, gradually warming the water in the tank. This kind of system can consume up to 60% less energy than a traditional water heating tank.

Much like the conventional tank, this option still requires maintenance and the tank does have the potential to corrode over time. Unlike the traditional tank, a leak in this system is more likely to come from an issue with the coils in the unit used to heat the water. Keeping these clean through regular maintenance will help to prevent any build-up, which may lead to malfunctions.

So, Can a Leaking Water Heater Be Dangerous?

There are a few reasons why a leaking water heater can be dangerous:

  • If left unchecked, a leak can grow and potentially flood and damage property
  • A leak can cause a fire if the water comes into contact with electronics
  • Too much pressure left to build up can result in an explosion

Luckily, with regular maintenance, most of these issues can be dealt with and prevented. Though it may only be a small valve that needs replacing, by leaving it too long, you may have to replace the whole unit. In checking on your unit regularly, you should be able to find any leaks early, giving you ample time to investigate and call in a plumber.

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