Water Tank Cleaning and Disinfection
Cold water storage tanks are one of the most important risk areas in Legionella Management and their upkeep and maintenance is fundamental to ongoing controls. Under current guidance, tanks should be inspected on a 6 monthly basis.
Common problems include;
1. Poor Turnover / Over-storage – often tank are installed to service more people or building usage has changed leading to the water stagnating in the tank for 3-4 days before being replenished
2. Poor Flow – often tanks are set up incorrectly such that water only flows through one tank or one end of a large cistern leading to stagnation.
3. Silt / Scale – build up of silt and scale over time can provide nutrients for bacteria to grow
4. Tank Lids – lids that fit incorrectly or are made of the wrong type of materials can allow organic matter into the cisterns or themselves encourage bacterial growth.
All the above can lead to conditions suitable for bacterial growth and this applies not just to Legionella but a whole host of other organisms making tank a crucial part of water hygiene.
How often should I have the tanks cleaned?
It is a common misconception that cold water tanks should be cleaned on an annual basis. This is in fact only the case if water is stored for drinking purposes (this requirement in fact comes from the DWI (drinking water inspectorate). In this instance the tank should be drained, cleaned and chlorinated on an annual basis, the tank should meet Bylaw 30 and WRAS regulation as well as a bacteriological sample taken every 6 months.
If, as is common on most sites, the water is stored for toilet flushing, showers and hand washing the tank only need be cleaned when ‘routine inspection show it to be necessary’. This will depend on turnover, cistern set up and hardness / silt content of local water – specific recommendations are made following 6 monthly tank inspections.
What do Nemco have to offer?
Nemco are able to offer a comprehensive tank cleaning service to comply with all the requirements as set out in ACOP L8 and BS6700. Tanks are drained, physically scrubbed, hovered, disinfected to 50 ppm for an hour and then re instated. All work is completed with health and safety as the highest priority ensuring no site personnel are exposed to dangerous chemicals.
Nemco have numerous years experience disinfecting everything from domestic cold water tank right way through to water towers and large scale industrial cisterns.
Not a problem! Nemco have engineers trained specifically for confined space, working on flat roofs / loft areas meaning most jobs are possible.
Nemco also employ a specialist rope access team for inspection / cleaning and disinfection of high level water towers etc. Please see the ‘High Access’ section for further details.