Sulphur-reducing bacteria, which use sulphur as an energy source, are the primary producers of large quantities of hydrogen sulphide. These bacteria chemically change natural sulfates in water to hydrogen sulphide. Sulphur-reducing bacteria live in oxygen-deficient environments such as deep wells, plumbing systems, water softeners and water heaters. These bacteria usually flourish on the hot water side of a water distribution system
Hydrogen sulphide gas produces an offensive "rotten egg" or "sulphur water" odour and taste in the water. In some cases, the odour may be noticeable only when the water is initially turned on or when hot water is run. Heat forces the gas into the air which may cause the odour to be especially offensive in a shower. Occasionally, a hot water heater is a source of hydrogen sulphide odour. A nuisance associated with hydrogen sulphide includes its corrosiveness to metals such as iron, steel, copper and brass The odour of water with as little as 0.5 ppm of hydrogen sulphide concentration is detectable by most people. Concentrations less than 1 ppm give the water a "musty" or "swampy" odour. A 1-2 ppm hydrogen sulphide concentration gives water a "rotten egg" odour and makes the water very corrosive to plumbing
Hydrogen sulphide may be controlled by conducting a shock chlorination / disinfection.
To shock chlorinate the system do this
1 drain system
2 remove any cartridges and filters and reconnect system
3 wash system through with detergent and water.
4 flush all traces of detergent from system
5 fill tank ¼ full with and high strength Calcium Hypochlorate (HSCH) at the rate of 80 grams per 1000 litres. HSCH is readily available and is used for cleaning swimming pools. Read the instructions on handling and mixing.
6 fill the tank and leave for 48 hours
7 Empty into a sewer system
8 Refill with drinking water and leave for 30 minutes
9 Empty again and install new filters
10 Refill with clean drinking water.
You may think this is overkill but it should sort any problems
To remove low levels of hydrogen sulphide with NO bacterial problems, install an activated carbon filter. The filter must be replaced periodically to maintain performance