After the Shut Down Disinfect Plumbing Systems

When the orders to stay at home were issued and many offices, restaurants and other commercial businesses closed their plumbing systems became a breeding ground for bacteria warns the CDC. Stagnant or standing water in a plumbing system can increase the risk for growth and spread of Legionella and other biofilm-associated bacteria. Stagnant water can also lead to low or undetectable levels of disinfectants. The CDC advises all businesses to ensure that their water system is safe to use after a prolonged shutdown to minimize the risk of Legionnaires’ disease and other diseases associated with water.

Legionnaires’ disease causes pneumonia and can be lethal and mistaken for Covid-19. Legionnaires’ disease is caused by contracted by inhaling airborne water droplets containing viable Legionella bacteria. Such droplets can be created, by the spray from hot and cold water taps; atomisers; wet air conditioning systems, showers; and whirlpools, water fountains, etc.. Anyone can develop Legionnaires’ disease, but the elderly, smokers, alcoholics and those with cancer, diabetes or chronic respiratory or kidney disease are at more risk.

Recent research has found that Legionella bacteria not only thrive in stagnant water, but also thrive on rust from water pipes and corroding taps and plumbing components. Though most reported cases of Legionnaires’ Disease come from cooling towers and large buildings such as hotels and hospitals, offices, gyms, and even residences are possible sources

To reduce the risk you should flush out plumbing systems that have not been used for some time, (including showerheads and taps), clean and de-scale shower heads and hoses. Cold-water storage tanks should be cleaned and disinfected and water should be drained from hot water heaters, the tanks refilled and heater to 140 degrees Fahrenheit. Also, check for debris or signs of corrosion in the water system. Cold water should be stored below 68 degrees Fahrenheit. Legionella bacteria thrives between 68-115 degrees Fahrenheit and cannot survive above 140 degrees.

Water utilities, the Department of Health and other groups are trying to spread the word that the temporary shutdown of a building and reductions in normal water use can create health hazards for returning occupants. Two potential microbial hazards that should be considered prior to reopening  are mold and Legionella (the cause of Legionnaires’ disease). See the CDC and EPA guidance on reopening.

If your location has been closed or only minimally used during the shut down it is necessary to flush the entire plumbing system. Begin by draining the hot water tank and refill and bring up to 140 degrees Fahrenheit.

• Remove and clean all aerators (leave aerators off during flushing); clean all faucets and showerheads; discard any accumulated ice;
• Flush hot and cold water through all points of use (e.g., showers and sink faucets, hand held sprayers, fountains);
• Flushing may need to occur in segments in large buildings;
• Perform flushing with proper ventilation and personal protective equipment. Now is the time to wear a proper respirator or N-95 mask. Care should be taken to avoid inhaling water droplets, especially from shower heads; and
• Other water-using devices, such as water tanks, softeners etc. may require other cleaning steps in addition to flushing.