What causes a bad gasket in a water tank, and how to repair it?

The gasket in the water heater tank is a rubber seal, a significant element in controlling water leakage. Normally the number of gaskets a water tank has depended upon the number of heating elements in it. They are shaped to protect the connecting areas of the heating element.

A bad gasket causes water leakage from the connectors around the heating areas and causes irreparable damage to the water tank.  So, water tank repairs are important and they should be timely also.

Causes of a bad gasket in a water heater tank

The following are the bad gasket-causing factors that lead to water tank damage if not repaired in time.

Heat causes a bad gasket.

The water tank is purposely used to heat water to make it warm for winter use. The heating process is very sensitive for the gaskets because the high temperature increases the deterioration rate too. Instead, the low temperature does not have a specific impact on the composition of the rubber gasket.

Heat directly attacks the bonds between rubber molecules, which weakens the gasket and damages it. Sometimes the sudden expansion and contraction of gasket material due to impulsive changes in temperature cause a bad gasket. A bad gasket may become porous or deteriorate totally, which in turn causes water tank leakage.

Continuous moisture retention could damage the gasket

The water tank always contains less or more water in it. That is why it always retains some moisture, slowly deteriorating the connectors around the heating elements. Humidity changes gasket material by dissolving the rubber molecules into the water.

Continuous water absorption by the rubber connector causes a swell gasket with poor sealing action. Similarly, the drying of this rubber makes it hard and finally gets cracked. Hence, the moisture retention and sudden drying of the gasket break it into pieces and cause water tank leakage.

Sediment buildup causes gasket failure.

Water contains lots of salts and minerals that settle at the bottom of the water heating tank. These settling molecules clog the surrounding connectors of heating elements and make a thick layer on the gasket.

  • Sedimentation of salts and minerals over a long time makes the rubber seal a part of it. That means the rubber molecules with weak interactions start attracting sediments which fully damage the seal.
  • The hard thick layer of sediments with deteriorated gasket fails the water-keeping ability of the water tank.

Sedimentation also causes bad gaskets by affecting the heating ability of the water heater tank. The sediment buildup may cause a sudden temperature change that indirectly affects the gasket material and weakens it.

Seal failure due to Corrosion between rubber and metal

Humidity is the main factor that corroded the surface, which it retains for a longer time. In a water heating tank, corrosion creates an interface between the rubber seal and the metallic body of the tank. This interface removes the bonding of the molecular chains of rubber and converts it into a bad gasket.

The poor water holding capacity due to the bad gasket and the thin porous metal body of the tank leads to irreparable damage.

Most water tanks contain two heating elements, one on the top and another one on the bottom of the tank. The energy is exchanged from the top heating element to the bottom by the energy exchanger. It is the site where corrosion attacks and damages the seal at the end by damaging the heat transfer element.

So, these are some of the important things to keep in mind to get good water tank repairs.

How to Repair the gasket of the water tank?

Water tank users should follow preventive measures to avoid any damage. Following are water tank repairs methods you can choose.

·         Low temperature

For the smooth working of a gasket, there should always be a thermostat that controls temperature. The bad gasket due to temperature fluctuations would be repaired by repairing the heating elements.

Gasket deterioration due to its expansion at high temperatures could back up by providing the seal with a low temperature in the absence of light.

·         Reduce relative humidity (RH) value

Gasket failure because of high humidity would not be repaired but could be avoided. Reducing the relative humidity (RH) is the best way to avoid irreparable damage to the rubber seal.

Otherwise, it will be replaced after getting dissolved into the moisture content. In some cases, its physical structure could be restored by slow draining and drying.

·         Scrub off sediments

By adapting a routine maintenance practice, you can avoid a damaged water heater tank. Flush an undamaged seal’s layer of sediments.

Otherwise, replacement is the last option to stop the water tank leakage and make it able to hold water again. Hence the proper removal of the settling elements once in a weak would keep the gasket working efficiently.

·         Anode-rod maintenance

As corrosion is also due to the higher moisture content of the water tank. Hence, a similar RH value reduction could be adapted to avoid it. Another way of avoiding corrosion is to maintain the anode rod routinely, as it is involved in attracting corrosive elements.

Because corrosion always make some interface and damage both the tank body and the seal, so could not be repaired. Hence for the fully corroded seal, replacement is the last option.

The following steps can restore a bad gasket:

  • Removing sediments, dirt, or any other pollutants from connectors of the rubber seal.
  • Flush out gently the hard layer of salts and minerals by applying some cleaner.
  • Get rid of damaged patches from the gasket and fill the damaged portions with some repairing material or conditioner.
  • Provide the rubber seal or gasket with optimal conditions, low temperature, and a dark place.


Among the causes of water tank leakage a bad gasket or a gasket failure is the major cause of water leakage. The electric heater with two rubber seals (gaskets) could damage the water tank both from top and bottom. Hence maintaining the temperature, RH value, anode-rod, and cleaning would avoid it from making a bad gasket.

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