Clarwick have over 15 years experience of cleaning and disinfection of water systems.  We operate to strict codes of practice and have worked extensively in the pharmaceutical and health industries.  Our company mission is to provide appropriate chemical cleaning using the most environmentally friendly chemicals available.  We provide a fully documented service, with complete method statements, risk assessments, reports and certification of disinfection.

There are two standards that relate directly to disinfection of systems, they are BS 6700 which refers to new installations and the L8 which deals with the control of Legionella and Legionnaires disease.

BS 6700 declares that new installations should be disinfected and the standard details of the oxidising agent and contact times to be used.

The L8 relates to on-going disinfection and water system monitoring program that includes risk assessments and disinfection of any water systems that harbor and allow the proliferation of Legionella or other water borne bacteria.  While these standards are not law in Ireland it is considered good practice and for the most part adopted by many companies and public sector buildings.


Disinfection is the reduction of the number of micro-organisms and is usually achieved by introducing a chemical oxidising agent to a system for a specified contact period.


Sterilisation is the exterminating of all bacteria. This is generally achieved by intensifying the heat of the system beyond that which bacteria can survive. This is conducted through the hot water systems.

Disinfection is the reduction of the number of micro-organisms to a level which is unsafe for a specific purpose, disinfection is usually achieved by introducing a chemical oxidising agent to the system for a contact period.


  • New water mains.
  • New pure water loops.
  • New Domestic water installations.
  • Every system that could harbour bacteria and especially any that could support the proliferation of Legionella, these would be
    • Cooling Towers.
    • Condensers.
    • Calorifiers.
    • Heat Exchangers.
    • Domestic Cold Water Distribution Systems and Tanks.
    • Domestic Hot Water Distribution Systems and Tanks, especially systems with Shower Heads.

A risk assessment on the system should be carried out regularly for example every 12 months and a disinfection program would then be put in place as required.   However high risk areas such as Cooling Towers and Calorifiers should be disinfected at least every 12 months.