New pipework / Pre-Commission Chlorination

New pipework / Pre-commission chlorination for Legionella control

Legionnaires’ disease HSG274 Part 2: The control of legionella bacteria in hot and cold water systems Para 2.127 guidance states.
“Where necessary, hot and cold water services should be cleaned, flushed and disinfected in the following situations, as specified in BS 8558:

  • on completion of a new water installation or refurbishment of a hot and cold water system;
  • on installation of new components, especially those which have been pressuretested using water by the manufacturer (see the manufacturer’s instructions);
    where the hot and cold water is not used for a prolonged period and has not been flushed as recommended or the control measures have not been effective for a prolonged period. For example, this could be as little as two or three weeks, but will depend on the ambient temperature, condition of the water system, potential for exposure to aerosols and the susceptibility of
    users considered in a specific risk assessment;
  • if the system or part of it has been substantially altered or entered for
    maintenance purposes that may introduce contamination;!

Mains water connections

Chlorination, If your new supply is of 50mm internal diameter and above: Under the Water Supply (water fittings) Regulations 1999 (SI 1999, 1148), you will be required to disinfect your underground connection.

It is not unusual for water suppliers to request pipes are swabbed, flushed, filled with chlorinated water not less than 50mg/l and allowed to stand for 1 hour, following which the chlorinated water should be flushed out, the pipe refilled, and a sample taken.

The following typically has to be submitted prior to the connection being made:

  • A disinfection certificate
  • A method statement of the disinfection process carried out
  • The sample results

New water systems in Healthcare

Health Technical Memorandum 04-01: Safe water in healthcare premises HTM 04-01 Part A: Design, installation and commissioning Para 15.28 Commissioning checks of hot and cold water systems states.

“Upon satisfactory completion of the pre-commissioning checks, the systems should be cleaned, disinfected and flushed before refilling. Advice on cleaning and disinfection is given in HSG274 Part 2”.

BS 8558:2015 Guide to the design, installation, testing and maintenance of services supplying water for domestic use within buildings and their curtilages – Complementary guidance to BS EN 806

  1. Para 5.2.3 Flushing and disinfection – requires all new water systems to be flushed.
  2. The guidance also suggests flushing if the system is not used for 30 days.
  3. Larger pipes (with an internal diameter greater than 50 mm) or pipes in specialized installations, such as healthcare buildings, where contamination is suspected should be disinfected after flushing.
  4. Guidance on disinfection is given
    in PD 855468.
New pipework / Pre-Commission Chlorination

Disinfection addition

Different types/sizes of job require different methods of introducing disinfectant. Proportional dosing, circulation and bulk dosing are all possible.

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