News Brief

Returning to the Office? You Might Want to Test Your Water!

Returning to the office means ensuring occupant health, but a recent study published in PLOS Water highlights the hazards of water that has sat in plumbing for too long.

Photo of an open sink tap with water running

Fixture flushing is only a short-term quick-fix for stagant water.

Photo: Matthew Bowden. License: Public domain.
So you’ve been working remotely for a while and are thinking about returning to the office soon. Before you get your first drink or make that first pot of coffee, you’ll want to make sure the water is actually clean. According to a recent study in the journal PLOS Water, stagnant water can have significant impacts on water quality after sitting for just a weekend.

The report states that, due to stagnation, “Monday morning’s water quality consistently had a low chlorine residual concentration, greater TCC [total cell counts of bacteria], and greater levels of copper and lead compared to water found on Friday afternoons.”

This means that, in this study, as the water sat in the plumbing, the chlorine concentration decreased, leading to an increase in the amount of bacteria in the water. Though many people try to limit excessive chlorine exposure, chlorine controls the growth of harmful pathogens, such as Legionella.

While the bacteria levels rose in the water, so did the amounts of copper and lead. Copper concentrations exceeded the federal drinking water limit of 1.3 mg/L, according to the study, in four of the 12 fixtures. Furthermore, researchers found that “fixture flushing was a short-term and impractical approach to reduce elevated copper and increase disinfectant residual levels.”

The study was done on a single three-story building, and there were differences in the water quality depending on location of the fixture, type of fixture, and the amount of water that was run through it, but the data suggest that testing your water on Monday to determine the extent of potential contamination is worth it—especially if your office has not seen much use in the past couple years.

More on water quality

Resilient, Sustainable Water Management: A Holistic Approach

Net-Zero Water and More: Moving Beyond “Low Flow”

Published April 4, 2022

Ehrlich, B. (2022, March 18). Returning to the Office? You Might Want to Test Your Water!. Retrieved from

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April 18, 2022 - 5:42 pm

This is absolutely true, and something that is often overlooked by 'return to work' plans. Even the WELL Health Safety Rating didn't include mandatory testing for lead. In buildings with old / existing lead service lines the levels could be HUGELY elevated if systems sat stagnant for too long. (Not to mention considerations of legionella as well). Yet another reason for flushing and water quality testing.