Water Systems in Closed Buildings May Require Flushing and Testing

Plumbing systems in buildings closed or vacant for long periods may need to be flushed to safely remove stagnant water.

Water provided by the San Diego Water Authority and its 24 member agencies continues to meet all state and federal drinking water standards. But after water leaves the agencies’ distribution systems and enters private service connections, the water quality can deteriorate if water becomes stagnant.

Most commercial and industrial buildings have been partially occupied even during the COVID-19 shutdown, and HVAC and water systems continue to be maintained and operated even though many employees are working remotely. However, building owners and managers should take special care with plumbing systems in buildings that have been vacant or have had periods of low water use to protect the public and employees returning to work.

That’s because plumbing systems must be actively managed and maintained to prevent bacteria growth. Bacteria can flourish in pipes, fixtures and associated equipment (like fountains, cooling towers and HVAC systems) that aren’t used for several days. Schools, for example, commonly flush pipes before kids and teachers return from breaks.