Due to COVID-19 protocols, some buildings have been left unoccupied for some time now. Once Provincial Governments lift restrictions, and put in new regulations, these building may become occupied and put into use again.
When this happens, it is recommended that the domestic water system be flushed to expel any stagnant water in the system, debris from natural scaling inside metallic piping and stop the growth of legionella bacteria. This will apply mainly to Commercial (production, warehouse, etc.) and Light Commercial buildings (small businesses etc.).
It is recommended to hire a Trade Qualified Plumber to perform these tasks. If an owner or maintenance personnel choose to do this themselves, here is the recommended process:
- Bypass and separately flush and/or replace any filter systems.
- Remove all aerators from any faucets (bath tubs and outside taps do not have them), and any shower heads.
- Begin by running the cold water faucet or fixture closest to where the water line enters the building.
- Then open all the cold water faucets or fixtures sequentially moving to the furthest Faucet or Fixture.
- Allow them to run for a minimum of 20 minutes and then shut them off in the same order they were turned on.
- Flush any toilets at least once. Flush any ice machines, coffee machines, refrigerator water dispensers and any other appliances with a cold water connection, for a minimum of 5 minuets
- Flush any outside taps for a minimum of 10 minutes.
- Repeat the process for all hot water fixtures.
- Allow them to flush for a minimum of 45 minutes for a typical 40 us gallon Hot Water Tank (1.125 x ___ us gallons = minuets to flush). Ensure your hot water tank or tank-less units are operating at a minimum temperature of 50 deg. C for gas units and 60 deg. C for electric units (BC Plumbing code 2.6.1.12.)
- Replace any aerators and shower heads.
NOTE: It is recommended that each property owner create a Water Management Plan (WMP). The water system in a building may be affected by pandemics and various disasters, requiring the building to be unoccupied for a long period of time. Having WMP ensures that the water system within your building is safe for the occupants. Below are some links that will aid you in your efforts to do this.
Additional Resources:
- BC Centre for Disease Control (BCCDC), Communicable Disease Control, Section 5.0, Prevention of Legionella
- Vancouver Coastal Health (VCH), Water Stagnation Risks
- American Water Works Association (AWWA) Shutoffs and Return to Service Guidance
- Center for Disease Control (CDC), Water management tool kit