Water Tank Cleaning

Water tank cleaning is an important part of water hygiene. Neglected water tanks can be the perfect breeding ground for harmful bacteria including Legionella, E coli and TVC which can be present in water tanks for numerous reasons. To prevent or control these risks, precautions should be taken by keeping the system and water in it clean.

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Water Tank Cleaning - When?

Hot and cold water storage tanks should be visually checked and any remedial work carried out where necessary, annually in accordance with HSG274.

Hot water services and, exceptionally, cold water services should be cleaned and disinfected in the following situations:

• If a routine inspection shows it to be necessary
• If the system, or part of it, has been substantially altered or entered for maintenance purposes in a manner which may lead to contamination
• During or following an outbreak or suspected outbreak of legionellosis

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Chemical disinfection is carried out by chlorinating the water in the cold water storage tank to 20 - 50mg/litre free residual chlorine. It is then allowed to flow to all parts of the system and leaving to stand for an appropriate period, whilst monitoring the chlorine concentration throughout disinfection to ensure that there is a sufficient residual chlorine level. The system is then thoroughly flushed following chlorination. Cleaning and chlorination is carried out by fully trained staff in accordance with HSG274, following the procedures set out by BS8558:2015.

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Water Tank Cleaning Method Statement

1. Sign into site and obtain necessary permits to work
2. Perform full risk assessment of the water storage tanks and surrounding areas on PW0010
3. Before any cleaning or sterilisation procedure begins place warning boards in good view. Inform relevant site staff, particularly if the water supply is to be disrupted and ensure all staff fully understand the length of service loss and relevant consequences
4. Check for full and correct operation of the inlet and outlet valves (it is particularly important to ensure outlet valves are water tight in Duplex tank situations), isolation and ball valves to be included in this check, and then shut inlet and outlet valves
5. If the tank is a duplex system then back flush balance pipe from service tank by gently opening the outlet pipe to ensure no stagnant water remains
6. All outlet valves must be locked off with suitable lockout prior to starting work. Inlet valves should be locked out prior to entering the tank. Signs should be placed in visible areas to notify of the fact that valves have been locked out and should not be operated or tampered with
7. Drain the tank, ensuring drain points are sufficient to handle volume and drain rate. Submersible pumps can be used at this stage if drainage is adequate
8. Before entering any tank ensure all confined space precautions are undertaken and clean Wellingtons are worn. Ideally utilize gas monitor and forced air system to ensure levels of oxygen remain high whilst working within the tank
9. Photograph internal surfaces of the tank and the ball valve prior to beginning cleaning
10. Clean all internal surfaces with nylon brushes, nylon scourers and clean water only ensuring all dirt and debris is removed from the sides of the tank and the bottom of the tank is vacuumed clean
11. Re-photograph internal surfaces of the tank and the ball valve Remove cleaning apparatus, close any drain valves and begin to refill the system with fresh water by opening the inlet valve

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Water Tank Chlorination

Water tank chlorination and cleaning is a crucial part of water hygiene that should be given upmost priority. Advanced Water Technologies can carry out this service to the highest standards within the industry.

From the largest break tank to the smallest domestic type tanks, the attention to detail should remain the same.

Over time water storage tanks naturally gather contaminants that ultimately affect the water quality.

These contaminants can harbour bacteria such as E. coli and Legionella. Advanced Water Technologies are experts at chlorination and tank cleaning thus leaving you with a clean bacteria free system. Full certification is provided upon completion of the works and a full detailed report with photographic evidence will also be produced.

Chemical disinfection is carried out by chlorinating the water in the cold water storage tank to 20 - 50mg/litre free residual chlorine. It is then allowed to flow to all parts of the system and leaving to stand for an appropriate period, whilst monitoring the chlorine concentration throughout disinfection to ensure that there is a sufficient residual chlorine level. The system is then thoroughly flushed following chlorination.