Water quality assessment – Legionella

Any activity that is required to operate in accordance with the requirements of the Health and Safety at Work Act 1974 has a duty, under this legislation, to assess and manage any actual or potential risks from Legionella bacteria.

Apple Environmental can undertake water quality assessments and offer advice and guidance to ensure that you comply with HSE guidelines outlined in the HSE Approved Code of Practice L8 (Fourth edition published 2013).

For further information on the legal duties that an employer has to uphold please refer to the HSE document IACL27 Legionnaires’ Disease: a guide for employers.

Further information

The Approved Code of Practice (ACoP L8) applies to any work activity or premises in connection with a trade, business or other undertaking, where water is used or stored, and where there is a means of creating and transmitting water droplets which may be inhaled or digested.

With regard to this duty, a ‘water system’ includes all plant/equipment and components associated with that system. Therefore it includes all associated pipe-work, pumps, feed tanks, valves, showers, heat exchangers, quench tanks, chillers etc.

It is stressed that the system must be considered as a whole, and not in isolation. In addition, it is paramount that ‘dead legs’ and other parts of the system that see intermittent use are included in any assessment, as whenever they may be brought back on line they would have the potential to cause significant contamination of the rest of the system.

To comply with their legal duties, employers should:

  1. identify and assess sources of risk;
  2. check whether conditions are present or likely to be present which may increase the risk;
  3. prepare a scheme for preventing or controlling risk;
  4. implement, manage, and monitor any preventative or control mechanisms;
  5. keep a record of action; and
  6. designate a person to be managerially responsible.

In carrying out this assessment and in particular in the assessment of risk the following factors should be considered:

  1. the presence of legionella bacteria within stored water supplies;
  2. the presence of other micro-organisms within stored water supplies;
  3. the existence of conditions suitable for the multiplication and growth of such organisms;
  4. the presence of a nutrient source such as sludge, scale, rust, algae and other organic matter;
  5. a means of creating and disseminating water droplets or aerosols into the breathing zone;
  6. the existence of activities that may encourage the above; and
  7. the presence (and number) of personnel who may be exposed to such droplets and aerosols.

The essential elements of HSE guidance are as follows:

  1. controlling the release of water spray;
  2. avoiding water temperatures and conditions that favour the proliferation of bacteria;
  3. avoiding water stagnation;
  4. avoiding the use of materials that harbour bacteria and other micro-organisms, or provide nutrients for microbial growth;
  5. maintaining the cleanliness of the water system, and the water within it;
  6. the use of appropriate water treatment technology;
  7. managing the correct and safe operation and maintenance of the water system;
  8. maintaining an up-to-date plan of the layout of the system;
  9. ensuring regular checks on the cleanliness and integrity of the system; and
  10. maintaining records and other documentation relating to the management of the water system.