Bacteria: Downside to Reducing Water Use

08/03/2018 | By Klaus Reichardt

A report from the U.S. Geological Survey (USGS) had some slightly unexpected but very good news for Americans when it comes to water consumption. Very simply, we’re using a lot less.

The USGS conducts studies regarding US water consumption every five years. Referencing the report, The Washington Post reports that in per capita terms, domestic water consumption has “plummeted from 112 gallons per day in 1980 to just 82 gallons in 2015, a 27 percent decrease.”

Related: LEED Certification Tips: Water Efficiency

Similarly, Popular Science reports that the “national average per capita usage fell by six gallons [of water] per capita, per day, from 88 gallons in 2010 to 82 in 2015 … and down significantly from 100 gallons per capita per day in 2005.”

Reasons for Decreased Water Consumption

While there are several reasons for this reduction in water usage — which has been noted in both residential and commercial facilities — one of the main reasons is that we are finding ways to not use water as much as before.

For instance, in many situations, building users are now cleaning their hands with hand sanitizers. Although the Centers for Disease Control and Prevention (CDC) has reported that hand sanitizers are an effective alternative to handwashing because they can kill microorganisms on the hands, the CDC notes they should not be used to replace effective handwashing. Instead, use them more when a “quick clean” is necessary.

The other reason is that we are using water much more efficiently (for long-term water reduction strategies) today than in the past. We’re finding where water is being wasted and eliminating this waste, and we’re developing ways to use less water but still achieve necessary results.

Bacteria Found in Unused Faucets

However, there’s a potential downside: A March 2018 study by the University of Illinois at Champaign reported that bacteria contamination can develop on faucets that aren’t used for a few days or not used frequently enough.

In other words, if one of the ways we are reducing water consumption is by not using faucets, bacteria can develop inside pipes, which could affect water quality and potentially cause illness.

To come to this conclusion, the university researchers collected tap water samples from three dormitory buildings that were closed for a one-week school break. Samples were taken from taps before building closure and again after the taps had been left unused for the week.

“We performed a variety of analyses, including tests to determine the concentration of bacteria present in the before- and after-building closure samples,” says Wen-Tso Liu, coauthor of the report and professor of civil and environmental engineering at the school.

The tests revealed that:

  • Stagnant water samples closest to the spouts (the point at which water is released) on the taps had the highest amount of contamination.

  • Bacterial concentrations decreased when water was further away from the spouts.

  • While microbial concentrations were evident, none was considered a health risk after one week of stagnation.

  • Two “communities” of bacteria live in tap water: One that flows freely in the water and another that lives in films, called biofilms. Biofilms line the insides of the pipes bringing water to the faucet.

  • When tap water is contaminated, bacteria concentrations are highest in the first 100 milliliters of water flow, equivalent to slightly more than the first three ounces of water released.

Based on their findings, the researchers suggest that building users make it a practice to run water for a few moments before using water, especially if it’s in a building that hasn’t been used for a few days or where strict water reduction strategies are in place, eliminating the use of some faucets.

On topic: How Cool Roofs Can Reduce Water Use

“It is contrary to what we have learned about conserving water, but I like to think of it as just another basic hygiene step," Liu says. "We have made a habit out of washing our hands; I think we can make a habit out of running the tap for a few moments before use as well.”

She also commented that just because the water tested in this study would likely not be a health risk if consumed, as “communities continue to invest in green infrastructure that stresses water conservation, if interior plumbing were to become contaminated with harmful bacteria, that could lead to unforeseen public health problems.”

Plan Water Reduction Strategies

This research tells us it might be better for building owners and managers who wish to reduce water consumption to direct more of their efforts to installing high-efficiency toilets and low-water and no-water urinals, and to re-evaluate landscaping, installing vegetation that needs less irrigation.

There’s no health risk involved in taking these steps and they can help reduce water consumption significantly.


Water consumption reduction strategies that help with bacteria buildup in pipes and faucets.A frequent speaker and author on water conservation issues, Klaus Reichardt is founder and CEO of Waterless Co. Inc., based in Vista, CA. Reichardt founded the company in 1991 with the goal of establishing a new market segment in the plumbing fixture industry with water efficiency in mind. Along with the Waterless No-Flush urinal, which works completely without water, the company manufactures other restroom- and plumbing-related products.


Two handpicked articles to read next:


Related Coverage