As Virginia prepares to reopen, business and home owners need to be aware of the risks posed by stagnant water in their buildings. While covid-19 poses no threat to the water supply, the “usual suspects” can contaminate premise plumbing that has been shut down or run at a significantly reduced capacity. These include legionella bacteria, which causes Legionnaires Disease, as well as lead and copper.
We recommend that all businesses and building owners, including home owners returning after an extended absence, take the following steps to flush their water system as a part of their reopening plans:
1. Remove or bypass point-of-entry treatment units prior to flushing.
2. Prevent backflow or the siphoning of contaminants into plumbing (e.g., close valves separating irrigation systems from premise plumbing, disconnect hoses attached to faucets, etc.)
3. Organize flushing to maximize the flow of new water (e.g. opening all outlets simultaneously to flush the service line and then flushing outlets individually starting near where the water enters the structure).
4. Run enough water through all outlets (e.g., hose bibs, faucets, showerheads, toilets, etc.), removing aerators when possible. Typical durations in existing protocols range from 10 to 30 minutes for each outlet (duration varies based on outlet velocity).
5. Flush the cold water lines first, and then the hot water lines. Note: the hot water tank can be drained directly; it can require roughly 45 minutes to fully flush a typical 40-gallon hot water tank.
6. Replace all point-of-use filters, including the filters in refrigerators/ice makers.
7. Additional precautions may be warranted if there is biofilm development or excessive disruption of pipe scale.
Large buildings should take additional precautions in accordance with their Water System Management Program, or establish a plan if one does not exist. Additional guidance can be found here: