Just like food that sits in a refrigerator for too long, water that sits in a building’s pipes for too long can make people sick.
Harmful organisms, like the bacteria that cause Legionnaire’s disease, can grow in unmaintained appliances.
With certain pipe materials, water can accumulate unsafe levels of lead and copper, which can cause learning disabilities, cardiovascular effects, nausea and diarrhea
Drinking this water is a problem, but infections can also result from inhaling harmful organisms. This occurs when water splashes and becomes an aerosol, as can happen in showers, hot tubs, and pools and when flushing toilets or washing hands. Some of these organisms can cause pneumonia-like diseases, especially in people who have weakened immune systems.
The water inside a building does not have an expiration date: Problems can develop within days at individual faucets, and all buildings with low water use are at risk.
Keep the water flowing
To avoid water issues, “fresh” water must regularly flow to a building’s faucets. Most U.S. water providers add a chemical disinfectant to the water they deliver to kill organisms, but this chemical disappears over time.
Medical facilities, with their vulnerable populations, are required to have a building water safety plan to keep water fresh and prevent growth. Schools, which have long periods of low use during the summer, are advised to keep water fresh to reduce water’s lead levels.
Health agencies in the U.S., Canada, England, and Europe have released recommendations in recent weeks, advising that building water be kept fresh during COVID-19 stay-at-home orders. There’s some debate over the best way to do that, but the core message is the same: Do not let water sit in buildings.
If water isn’t being used in a building, intentionally flushing the building to replace all the old water with new water can be done at least weekly. It also helps remove sediments that accumulate along pipe walls.
Faucets, water heaters, and softeners, appliances such as refrigerators, toilets and other water systems, including cooling towers, all need to have water turnover. Some of these can require specialized attention. Faucet aerators should be removed because they accumulate materials and slow down the flow.
How long flushing takes depends on the building’s piping design, devices and the speed of water exiting the faucets. All buildings are different.
It took more than 80 minutes of flushing to draw freshwater to the farthest faucet of one 10,000-square-foot building. In another building, it took 60 minutes just to get fresh water from the water meter to the basement of a building 30 feet from the street. A single large building may take hours or days to clear.
Easier to avoid contamination than clean it up
For building managers who haven’t been running the water during the pandemic, the water sitting in pipes may already have significant problems. To perform flushing, safety equipment, including masks, currently in short supply, might be needed to protect workers.
A slow “ramp-up” of the economy means buildings will not reach normal water use for some time. These buildings may need flushing again and again.
Shock disinfection, adding a high level of disinfectant chemical to the plumbing to kill organisms living in it, may also be necessary. This is required for new buildings and is sometimes done when water in new buildings sits still for too long.
Building owners and property managers need to start planning and maintaining their water supply now so that it is ready by the time employees return to work.