The Risk of Legionella Lurking in Water Systems after COVID Closures

As schools begin to reopen in certain communities, in addition to concerns over the spread of the coronavirus, officials are also worried about the increased risk of deadly illnesses caused by bacteria after months of closures. In fact, a dozen schools have already reported the detection of Legionella in their water systems, a warning to all property owners and managers – from offices to hotels and restaurants – to undertake risk-mitigation measures in order to help prevent potential outbreaks of Legionnaires’ disease.

Legionella pneumophila is the bacterium that causes Legionnaires’ disease, a respiratory condition. It can form in stagnant water and then disperse through the air and be inhaled when, for example, one is in the shower or if a tap is turned on. It can be fatal in one in 10 cases, according to the Centers for Disease Control and Prevention (CDC). Adults and individuals with compromised immune systems are particularly vulnerable to the disease.

Developing a Water-Management Plan to Mitigate Legionella Risks

Because commercial, industrial and educational facilities were closed amid the pandemic, bathrooms, showerheads, taps, cooling towers, air-conditioning systems, pools, hot tubs, and water fountains went unused, which can cause water to become stagnant in the plumbing – a breeding ground for bacteria to grow. The extent of stagnation, according to the Water Quality & Health Council, will vary between buildings based on a variety of factors. These include the length of closure, size of the building and number of occupants, complexity, and condition of the water system, and whether maintenance had been performed during the shutdown. 

The CDC has issued guidelines to help prevent Legionella that apply to all businesses and building reopenings after coronavirus lockdowns. An important first step to reopening a building (or maintaining safe operations in a building with reduced occupancy) is to develop a building water-management plan that evaluates all the uses of water within the building and the potential health risks, including those from Legionella.

One critical measure in a water-management plan in guarding against Legionella growth is a process known as flushing. This involves bringing fresh water into the system, which keeps a small dose of chlorine in the system and limits the bacteria’s ability to propagate. Flushing has to be done regularly and for all outlets, which means running every tap, shower, and toilet. In addition, sanitize pipes and disinfect cooling towers that use water to lower air temperature. Hot water heaters and other water-using devices, such as ice machines, may require additional cleaning steps. For instance, drain the hot water heater or discard old ice per manufacturers’ instructions.

Property owners should also be alerted to the potential of bringing stagnant water from water mains into the building, which may exacerbate water quality issues. Check with the local water utility to confirm that the water mains in the neighborhood have experienced sufficient water usage, or if remedial measures such as flushing have been implemented. This is particularly important for buildings located in downtown areas, business parks, and campuses, where a substantial decrease in occupancy has occurred on a neighborhood-wide scale.

Speak with your clients about ensuring they implement water-management measures before reopening their properties.