Maintaining or Restoring Water Quality in Buildings with Low or No Use

Building and business closures for weeks or months reduce water usage, potentially leading to stagnant water inside building plumbing. This water can become unsafe to drink or otherwise use for domestic or commercial purposes. For example, optimal growth conditions for undesirable pathogens, such as Legionella bacteria, can occur when hot water temperatures decrease and disinfectant residuals (e.g., chlorine) drop to low levels. Water chemistry changes may also increase corrosion and leaching of metals, including lead, and may cause the formation of disinfection by-products. Turning on the water for immediate use after it has been stagnant can pose a risk to public health if not properly managed. Additionally, turning on water after a prolonged period of non-use could disrupt pipe and plumbing scales to such an extent that microbial and chemical contaminants could be released in the water. 

For more information on the EPA's recommendations that building owners and managers take proactive steps to protect public health by minimizing water stagnation during closures and taking action to address building water quality prior to reopening, please refer to the following links: