Keep water systems well maintained

It is very important that while many businesses and offices are shut down due to the pandemic, water systems are still well maintained to prevent future health issues like Legionella outbreaks. In vacant or partially unused properties, water can stagnate within water systems. This can lead to Legionella bacteria growing to harmful levels. Somebody could contract Legionnaires' Disease when water systems are brought back into use.


Legionella bacteria is commonly found in water. The bacteria multiply where temperatures are between 20 and 45°C, nutrients are available, and water is left undisturbed. The bacteria can cause Legionnaires' disease. This is a potentially fatal type of pneumonia, contracted by inhaling airborne water droplets containing the bacteria. These droplets can be created, for example, by hot and cold-water outlets, wet air conditioning units, and whirlpool baths or hot tubs.

How to maintain your water systems

Do these things during the pandemic and prior to reopening. This list is not exhaustive and will need to be adapted to your own situation.

Your insurance company may also have advice or specific requirements for you to complete prior to reoccupation or opening.

Do not worry about overdoing flushing of systems. The more water movement, the cleaner the system will be.

Taps, toilets and showers

  • Make sure all taps in the building are flushed. Start by running slowly at first and then increase gradually to full bore. Run cold taps until the water runs as cold as possible and hot taps until they run as hot as possible (there is no time limit on this, it will vary in different parts of the building).
  • Flush all external taps the same way.
  • Flush all toilets, where possible with toilet seat down. If there is no toilet seat, people should leave the room during and after flush. Repeat - two flushes for each toilet.
  • Flush showers the same way as taps but keep the shower head as low to the tray or ground as possible to minimise spray. Then clean and disinfect all shower heads (including back wash showers).

Kitchen and washing appliances

  • Put dish washers, glass washers and washing machines on a cycle but, for fire precautions, do not leave them running in a vacant building. If necessary, set the machine on a rinse cycle, do the other flushing tasks in the building and return to check how long is left of the cycle. If the appliance can be set to drain or spin, it will empty. The appliance does not need to go through a full cycle.
  • Kitchen appliances that use water including steam ovens need to be run on a weekly basis.


  • Do not turn off, isolate or drain Zip boilers as this could create dead legs in the system. Run water through them until they run cold so that water in the reservoir in the machine has been turned over.

Other flushing advice

  • Ensure that cold water dispensers, drinks machines, vending machines, coffee machines, taps in boiler houses, old toilets and stores are all flushed.
  • Garden hoses not in regular use need to be disconnected from the tap and flushing carried out from the tap itself.
  • On large sites where there are hot and cold storage tanks and/ or long lengths of pipework in the water distribution system the flushing should attempt to match the normal usage pattern within a building (for example you need to turn over as much of the tank water as possible and the larger hot water cylinders).
  • In systems that have not been flushed for a while you may need to consider disinfection - this will need expert advice.
  • If you have a complex system, such as a calorifier or spa pool, you are advised to seek expert advice from a water treatment company specialising in the control of Legionella growth.

Record what you do

You MUST record your actions to provide evidence of compliance.

More information on Legionella and your duty as an employer or landlord

Legionella and Legionnaires' disease