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Water Heater Problems


Heating water causes calcium carbonate to precipitate out and settle to the bottom of the water heater. Water that gets under this layer of sediment can turn to steam when the burners come on and cause popping and other noises. The build up of sediment can reduce the efficiency of your water heater and reduce the holding capacity.

Regular flushing of the water heater through the drain valve can help prevent sediment build up and other water heater problems. Sediment can reduce the efficiency of the water heater and get into re-circulating lines and cause problems with circulating pumps and check valves.

Smelly hot water

Anaerobic bacteria reacting with the magnesium anode forms hydrogen sulfide gas. This gas smells like rotten eggs. Hydrogen Peroxide can be used to get rid of the bacteria but it usually returns. Replacing the magnesium or aluminum anode rod with a zinc/aluminum alloy rod will often get rid of the problem.

Insufficient Hot Water or Hot Water Not Hot Enough

Check for a broken dip tube, wrong setting on a thermostat, a defective thermostat, burned out heating elements (electric), or a heavy build up of sediment. Check out our trouble shooting guides.

Dip Tube

The dip tube is a long slender tube that fits down into the water heater inlet. The dip tube directs the incoming cold water down to the bottom of the tank. If the dip tube is broken, the incoming cold water can mix with the out going hot water and cause it to seem as though the water heater is running out of hot water.

Noisy Water Heater

Noise coming from gas water heaters can often be caused by the sediment build up in the bottom of the water heater. As the burners heat the bottom of the tank gas bubbles form under the sediment. The thumping and popping noises are created by the gas bubbles escaping from under the sediment. Sizzling noises can be caused by condensation dripping onto the hot burner.

Thermal Expansion

When water is heated it expands. If the inlet to the water heater is not blocked by a check valve, pressure reducing valve, or other device, the increase in volume simply travels back into the water source. If the inlet is blocked, this increase in volume will cause an increase in pressure, sometimes to dangerous levels. The T&P valve should relieve this pressure by discharging some water. A thermal expansion tank can be installed in the water line that will absorb the increase in volume preventing the relief valve from discharging water unnecessarily.

Water Hammer

The hammering and pounding noise and associated vibration that occurs when a column of moving water within a piping system is suddenly stopped by a valve is known as "water hammer". When water is traveling in the pipes it has kinetic energy (energy of motion). When a valve shuts off suddenly a shock wave results. Not only is an annoying noise created, but damage to the plumbing system can occur. Water hammer most often occurs when a valve shuts off suddenly as with solenoid valves. Commercial water hammer arrestors are available to combat this problem. They consist of a small air bladder within a cylinder plumbed to the piping system near the valve causing the problem. They cushion the moving column of water. Some hardware stores carry them. Sometimes if the water piping is sagging then supporting the pipe solves the problem.


Condensation often occurs on water heaters when a large hot water draw occurs and thus a large amount of cold water enters the water heater. This condensation is sometimes mistaken for a leak in the water heater storage tank.

Scalding Dangers

Homes that have small children, elderly and disabled persons may wish to lower the water heater setting to 120 degrees to prevent potential scalding. Below is a Table giving the approximate time it takes have a scalding accident for different temperatures of hot water.

Length of time for hot water to cause scalding

  • 125 F 1 1/2 to 2 minutes
  • 130 F About 30 seconds
  • 135 F About 10 seconds
  • 140 F Less than 5 seconds
  • 145 F Less than 3 seconds
  • 150 F About 1 1/2 seconds
  • 155 F About 1 second
Earthquake Safety

A 50 gallon water heater holds about 400 pounds of water. In an earthquake it is quite possible for the water heater to fall over. Having a 400+ pound water heater fall on you, a pet, or even your property is not desirable to say the least.

If a gas type water heater falls over it could very easily damage the gas connection and create a dangerous gas leak.

Preventing the water heater from falling over will also eliminate the need for cleaning up a 50 gallon hot water spill and the expense of replacing the water heater should it be damaged in a fall.

Should the water heater fall over it could also damage the water piping and create a very large mess as well as wasting valuable water and contributing to a reduction in the water pressure available for fighting fires that can accompany earthquakes.

Water heater strap kits are available and sometimes even required by local building codes.

Milky Hot Water

Water contains dissolved oxygen and other gases. When water is heated it has less ability to hold these gases and when the pressure is lowered as the water comes out of the tap these gasses can form tiny bubbles giving the water a milky appearance. Letting the water stand for a few minutes will allow these bubbles to rise out of the water and the water resumes its clear appearance.

Water Heater Sizing

To determine the right size water heater for your home you must figure out the peak demand that will be required from your water heater. The table below lists typical amounts of water for various uses. Decide what activities will occur simultaneously and choose a water heater that can handle the required load.

Hot Water Consumption Table
Activity Gallons per use
  • Shower or Bath 10 to 20 gallons
  • Shave 1 to 2 gallons
  • Hand/Face Wash 1 to 4 gallons
  • Dish washing (hand) 2 to 4 gallons
  • Dish washing (automatic) 12 to 14 gallons
  • Food Preparation 3 to 5 gallons
  • Clothes Washing 10 to 32 gallons

The hot water supplied by a storage type water heater will begin dropping in temperature before the total water in the heater is consumed due to the mixing of incoming cold water.


For a family of four the following activities may occur:

  • 8:00 a.m. Adult takes shower and shaves 18 gallons used
  • 8:15 a.m. Adult takes shower 15 gallons used
  • 8:30 Two children wash face/hands 3 gallons used
  • 8:40 Breakfast food preparation 3 gallons used

Total hot water required for one hour: 39 gallons

To insure full temperature hot water choose a water heater with a first hour rating of 40 gallons or more.