Water tank cleaning and disinfection


Do I need a water storage tank clean and disinfection?

  • If a routine inspection shows it to be necessary (see images below).
  • If the system or part of it has been substantially altered or entered for maintenance or remedial purposes in a manner that may lead to contamination, or
  • During or following an outbreak or suspected outbreak of Legionellosis.

"The risk from exposure to Legionella should be prevented or controlled; precautions include keeping the system and the water in it clean."
ACoP L8, paragraph190.

Cleaning and disinfection of the tank and services is recommended when there is visible evidence of any of the following:


Stagnant water

Stagnant water




Animal contamination

Floar growth

Flora growth


Corrosion (although tank replacement would be recommended in these cases)

See our rogue's gallery which demonstrates the extremes of poorly managed water systems.

What is involved during a clean and disinfection?

Clean and disinfection services are carried out in accordance with ACoP L8 following the procedures outlined in PD855468 and HSG274 Part 2 (BS 8558:2015).

  • An engineer will visit your site and initially conduct an assessment to identify any additional health and safety precautions required.
  • Isolation of the cold water storage tank and any pump sets.
  • Fully drain the tank and undertake a physical clean to impeccable aesthetic standards.
  • Chemical cleaning using silver based hydrogen peroxide - the use of this chemical halves the volume of water needed to be 'dumped' than using conventional methods.
  • Use of alternative chemicals such as chlorine and bio/oil dispersants where applicable.
  • Where required, full system disinfection including all assets and pipe work, measuring chemical levels at every outlet to ensure successful disinfection.
  • Tests carried out for TVC, e-coli, coliform and Legionella by a UKAS accredited laboratory (see Microbiological sampling).
  • Issue of disinfection certificate and sample results for your log book.

Why choose W.E.T for your clean and disinfections?

  • Strictly compliant:
    Cleaning and disinfection services are carried out in line with ACoP L8 by following the procedures set out by PD855468 and HSG274 Part 2 (BS 8558:2015) to keep you compliant.
  • We have seen it all:
    Over 20 years experience in the field has presented our engineers with a wide range of site issues, so you can be reassured we will recommend the most effective solution for your needs.
  • Remedial work and tank refurbishment:
    In addition to planned maintenance, our experience as a tank manufacturer and trained plumbers enable us to identify and provide reactive works (see tank refurbishment and remedial works) efficiently and cost effectively to an extremely high service standard.
  • Responsive and reassuring:
    In the event of any out of range microbiological results, we have strict procedures in place to remedy the situation, fast tracking action where possible and responding to site usually within 24 hours to minimise any required system shut down.
  • Quality standard:
    All clean and disinfection services are managed under our quality standard ISO 9001:2015 to ensure we maintain a high standard of service when on your premises.
  • Accredited by the Legionella Control Association:
    Services are carried out under internal procedures which have been accredited by the Legionella Control Association to ensure year round compliance and quality of service to our clients.
  • Dedicated account management team:
    We implement a customer relationship database in house which provides reminders to our account management team to ensure we keep on top of your system cleanliness.
  • National Water Hygiene Card Holder:
    All W.E.T engineers are National Water Hygiene Card holders, which is recognised by all UK water companies and is a pre-requisite for any work on the water distribution network.
Our friendly and experienced customer service team are here to help you.


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Registered in England No. 2685141