Cold water tanks accumulate sediment at a varying rate. When the base of the tank is obscured by sediment it is usually time to remove this by chlorinating the tank, draining the water and removing the sediment. The tank is then refilled and chlorinated to 50ppm chlorine for 1 hour. Some tanks require annual cleaning and disinfection while some building managers particularly in high risk properties such as care homes and healthcare departments opt for annual clean and disinfection as part of their legionella control scheme.
If chlorination is carried out in response to legionella colonisation then the water is circulated to outlets and the dose checked over an hour period increasing the chlorine present as required to maintain 50ppm.
During cleaning and chlorination we can treat, paint and seal any corrosion of metal tanks and install lids, vents and screens to ensure the tanks are compliant with the approved code of practice.
Showers and taps may accumulate scale which has to be removed so that bacteria cannot shelter and grow. Descaling taps and disinfecting shower heads is an essential part of legionella control.
Alternative treatment chemicals such as Silver Catalysed Hydrogen Peroxide (not allowed in water systems supplying dialysis systems) may be used where chlorine is unacceptable due to the risk of occupant exposure or of corrosive deterioration from chlorination.