- Your storage cisterns should be installed properly to ensure that they have close fitting lids and screened overflows. This will prevent the entry of both light and insects.
- It should also be properly insulated against both heat and cold.
- The capacity should not exceed 24 hours normal usage.
- There must be an air gap to prevent back siphonage.
What Guidance is there?
BS EN 806: Specifications for installations inside buildings conveying water for human consumption
BS 8558: This provides complementary guidance to BS EN 806 and offers detailed guidance on the design, installation, testing, operation and maintenance of services supplying water for domestic use within buildings and their curtilages.
When should you disinfect the water system?
There are numerous instances when water services are required to be cleaned, flushed and disinfected. According to HSG274 (part 2) these include:-
- Following completion of a new water installation (or refurbishment of a hot and cold water system).
- Following installation of new components, especially those which have been pressure tested using water by the manufacturer.
- Whenever the hot and cold water is not used for a prolonged period. This could be as little as two or three weeks, but will depend on the ambient temperature, condition of the water system.
- When a routine inspection of the water storage tanks shows there is evidence of significant contamination or stagnation;
- If the system or part of it has been substantially altered or entered for maintenance purposes that may introduce contamination;
- Following water sampling results that indicate evidence of microbial contamination of the water system
- During, or following an outbreak or suspected outbreak of legionellosis linked to the system;
- If a risk assessment deems it necessary.
Water quality testing
It is always prudent to confirm the effectiveness of a disinfection with a laboratory analysis of the water. For example, for cold water storage tanks, the cost of a “potability” test is just over £30