Water from Heater Smells

Problem: Hot water from water heater has odor.

Background: At least one anode rod is installed in every water heater to provide corrosion protection for the tank. Certain water conditions will cause a reaction between this rod and the water, causing the hot water to assume a “rotten egg” smell. The odor results from hydrogen sulphide gas becoming dissolved in the water.

 

What to do: For the odor to develop, four factors must be present (1) a concentration of sulphate in the sup ply water, (2) little or no dissolved oxygen in the water, (3) a sulphate- reducing bacteria within the water heater (a harmless bacteria non-toxic to humans), and (4) an excess of active hydrogen in the tank. To remedy, do not simply remove the anode(s), leaving the tank unprotected. The odor may be reduced or eliminated in some water heaters by replacing the anode(s) with types that have less active material, and then chlorinating the water heater tank and all hot water lines. Check with the manufacturer or dealer for replacement anodes and chlorination equipment.

Special advice: Hydrogen is generated by the corrosion-protective anode, and hydrogen gas can build up in a hot water system unused for 2 weeks or more. This gas is extremely flammable and explosive. As a precautionary measure, open the hot water faucet for several minutes at the kitchen sink before connecting any electrical appliance to the hot water system (such as a dish washer or a washing machine). If hydrogen gas is present, there will likely be a sound similar to air escaping through the pipe. Do not smoke or have any open flame near the faucet when you open it.

Helpful hint: If smelly water persists after anode replacement and chlorination treatment, consider in stalling continuous chlorination and filtering conditioning equipment to reduce the problem.