Building reoccupation after coronavirus

As a result of closure or part closure of buildings drinking water systems may have been subject to stagnation due to low turnover of mains water or water in storage. This could have resulted in warming of water in internal plumbing systems, microbiological regrowth or increased uptake of plumbing metals. Unless steps are taken before the building is reoccupied there is a risk of adverse drinking water quality including potential risks to health. This can occur in both plastic and metallic pipes and can also give rise to taste and odour problems.

It is critical that building owners, managers and landlords take action to manage the risk of water systems that have not been used, to ensure that as staff return, water systems are safe. In the first instance it is likely that a methodical flush of all pipework and tanks will be sufficient to restore drinking water to the expected quality.

In some cases it may also be necessary to consider disinfection of pipework. The Water supply (Water Fittings) Regulations 1999 gives guidance on the requirement for disinfection of water systems where they have not been flushed or have not been in regular use, for a period of 30 days or more. BS 8558-2015 Sets out the flushing and disinfection procedures, if these are followed then the Water Supply (Water Fittings) Regulations 1999 are deemed to have been satisfied.

The decision to flush the system or disinfect is dependent on the individual system and the relevant building management plan, but this should also include the hot water system and should be carried out in the following order;

  • The incoming mains supply.
  • Service pipes and storage cisterns.
  • Distribution pipes All appliances should be through flushed before use.

If the property has any internal filters or water softeners, these should be checked to ensure they are working correctly as outlined in the manufacturer’s instruction manual. It is recommended that an approved plumber is used for any work a qualified professional can be found on the WaterSafe website at WaterSafe.org.uk they will certify that the work has been carried out in accordance with the regulation.

Business customers should contact their retailer should they require further information after following this simple flushing advice. The Drinking Water Inspectorate has also published detailed advice upon their website (DWI.gov.uk).