Water heaters are a crucial component of any plumbing system.  Hot water in showers, dishwashers, and washing machines are heated using hot water heaters. 

However, if the pressure within the water heater in your home gets too high, it could leak or even explode. Why does a water heater build up pressure, and how can it be prevented? 

The following article will explain “what causes too much pressure in hot water heaters” and describe how the water heater in your home can build up to a potentially lethal amount of pressure and the safeguards designed to stop that from happening.

How Do Hot Water Heaters Work?

A water heater can use electricity or gas to warm water in a storage tank. Insulation in foam or fiberglass keeps heat inside the tank. The tank is usually made from steel. 

The heating system uses the power source (gas, electricity) to bring the cold water inside the tank to the desired temperature.

An electronic thermostat controls your heating element’s on/off status based on the water’s temperature.

Convection is the technique of heated water evenly distributing itself across a container by rising to the surface while colder water sinks to the bottom. 

When you use hot water from your shower or sink tap, cold water goes into the tank from the base and gets heated by the boiler as it rises to the top. 

There will be a constant influx and outflow of cold and hot water inside the tank until thoroughly heated.

What Causes Too Much Pressure in Hot Water Heaters?

Several things can contribute to a water heater’s pressure being too high.

1. An Alarming Increase in Pressure

An excessive accumulation of air or steam inside the tank is the most typical factor causing increased pressure in an electric or gas water heater. 

Excessive pressure can occur if minerals or sediment deposits clog your heat exchangers inside the storage tank, keeping the hot or warm water from escaping correctly as air or steam. 

As a result, the temperature and pressure inside the tank rise, which increases the risk of catastrophic events like water leaks, bursts, and explosions. 

The pressure in the water heater could be higher than usual if the house doesn’t have enough ventilation.

2. Mineral Deposits             

Tap water contains naturally occurring minerals such as magnesium and calcium, and these mineral deposits on the tank’s interior walls can cause reduced efficiency and pressure problems.

It is essential to flush out the tank regularly to remove any silt or mineral buildup that may have accumulated to avoid mineral sediments accumulating in pipes. 

What Causes Too Much Pressure in Hot Water Heaters

Flushing your tanks and pipes will prevent pressure in the tank from becoming too high and causing problems.

A  full-house filtration system can help lower the concentration of minerals in the water, so it’s worth considering if you want to improve the quality of your drinking water.

3. Wrong Setting on the Thermostat

Wrong temperature adjustments on your thermostat control in the water heater tank are another potential high-pressure source

If you raise the temperature too high (over 120 degrees Fahrenheit), the pressure inside the tank could rise. As previously discussed, the high temperatures and increased pressures lead to leakage and other problems.

To avoid this problem, setting the thermostat to never rise beyond 120 degrees Fahrenheit is important. 

Setting your thermostat to the right temperatures will assist in maintaining safe internal pressures in the unit, irrespective of the duration it’s been on.

4. Lack of Space for Expansion

The expansion of the liquid due to its temperature causes a more significant internal pressure in your water heater tanks and pipes. 

The tank’s expansion will relieve the tank’s internal pressure and provide a destination for the surplus water. 

Buildings with closed plumbing channels require expansion tanks for extra space. A closed system prevents water from entering the house’s plumbing or draining into the primary piping system.

The Importance of the Expansion Tank

An explosion could be among the worst possible outcomes for the water heater. However, other problems may arise from using a strong water heating tank, such as damage to your plumbing system, home appliances, and water heater. 

Normal procedures will cause the tank pressure to increase as water is heated. 

The increase in pressure in the tanks happens because the water heater’s components deteriorate more rapidly once the waters spread, and it becomes increasingly difficult for the water to find a way out. 

They might even fail to heat or warm the water. Furthermore, suppose the pressure increases to the level that the temperature & pressure valves open. 

In that case, there is a risk of water causing harm to the flooring and walls adjacent to the heating element.

The water pressure coming in may be more than your hot water equipment or appliances can handle, which will cause them to wear out faster. 

The strain on your home’s plumbing system could lead to small leaks that could snowball into a major emergency.

With an extension tank, though, all that excess hot water will have a place to go. Expansion tanks help to achieve constant internal pressure. There is a risk of hot water leaking into your expansion tank when pressures are too high.

What to Do If Your Hot Water Heaters Are Under Pressure

Recognizing the early indications of increased pressure in the water heaters is crucial in preventing catastrophic failures. 

An elevated internal temperature is a common indicator. If the temperature in your water heater is rising steadily, it may indicate that the air pressure in the tank is growing.

Your home’s water heater may be making an unusually loud noise. A possible sign of internal pressure buildup requires opening the safety valve. Some other symptoms of elevated pressure are:

  • Diffusely hot or cold spots
  • Problems with tank leakage or corrosion
  • bubbling and hissing sounds
  • Discolored, rusty water from the sink or the shower

Problems Associated With High Water Pressure in a Water Heater

An excessive amount of pressure might cause serious problems for a water heater.

1. Water leaks and flooding

Pipes may rupture under strain, allowing water to seep into otherwise dry places like ceilings, floors, and walls, resulting in expensive repairs. Sometimes, these incidents might cause enough water to flood a whole house or structure.

2. Worsening Problems in Networked Systems

The increased pressure will exacerbate any preexisting flaws or weaknesses within your valves and pipelines by pushing them apart while they should have remained closed and vice versa.

3. Tank Damage  

Damage to a water heater’s heating components and tank might result from excessive pressure. In a water heater, high water pressure might cause problems for components that can’t withstand high temperatures.

4. Bills Associated with Water Use Become Too High

Leaks from broken fixtures suffering under the weight of an imbalanced plumbing system might result in high water bills owing to waste.

5. Danger to the Environment

These problems are not only financially costly but also threaten the local ecosystem. Without repair, they threaten nearby water supplies and ecosystems by allowing contaminated runoff to spread.

6. Danger of Suffering an Accidental Injury

Overlooking excessive pressure could endanger people’s lives by cutting off their access to hot water or suddenly causing them to experience burning while showering. 

What Causes Too Much Pressure in Hot Water Heaters

A dangerous accumulation of steam pressure may trigger an explosion if a defective valve allows it to accumulate.

When Does High Water Pressure Become a Problem?

Your plumbing is vulnerable to damage. Water has profound effects on the domestic or home environment. Its damage builds up slowly but steadily, and it often goes undetected. 

The constant starting and stopping of water flow within your pipes causes wear and tear and, eventually, small leaks. These leaks may not look like much, but they can lead to costly ruptures of pipes and severe structural damage if left unchecked.

Your warmer may break. It grows bigger when warmed up. Most warmers have a heat expansion tank to help with the extra storage space. 

If the water pressure exceeds 80 psi, your water heater tanks could burst without enough space for the expanded water.

Ways of Preventing Excessive Pressure in Water Heaters

A water heater’s safety features will kick in if the pressure inside the tank gets too high. Even so, these safeguards can fail or be tampered with on occasion. They might not be in operation at this point.

Temperature and Pressure Valves

All water heaters that use a tank must have a temperature and pressure valve, often called a pressure and temperature relief valve. 

According to building regulations, a pipe must run down the sides of the water heater tanks from the sides of the top.

The T and P valve will release pressure when the tank’s internal temperature reaches 210 degrees Fahrenheit and the pressure inside the tank reaches 150 pounds per square inch. The release of pressure will cause the valve to seal.

If there is a puddle of water around your T and P valve, the pressure in your tank may have risen too much to seal it properly. If this has become a persistent issue, it is best to have a professional investigate.

High Limit Switches

When the water temperature in the tank exceeds 180 degrees Fahrenheit, a high-limit control switch automatically activates. The water heater’s power supply is cut off when the switch is turned on. 

If you have to restart the water heater frequently, there’s something wrong with it. If you need assistance, it’s best to call a plumber.

Water heaters that blow up

It’s not common, but water heater explosions do occur. Ensure your T and P valves and water heater operate well by doing routine maintenance.


Regular maintenance is essential in preventing excessive pressure or an overheating water heater from posing a threat. 

Proper maintenance and care involve yearly tank inspections for silt buildup and monthly checks for line cracks or leakages. 

Any discrepancies discovered throughout any of these examinations warrant prompt, professional attention. Ensure you’re putting only a little strain on your system by using an expansion tank that’s too small for your unit.