Fairfax Water flushes the past year out of its system, leaves funny smell

It’s time for Fairfax Water’s annual flush, meaning the fire hydrants are flowing and the water might smell a little funny.

Every year, water companies flush their systems in order to clean out and remove sediment from water mains and pipes that have accumulated. This sediment occurs from internal corrosion as well as natural build-ups of iron and manganese.

It also ensures that chlorine contraction levels, which disinfect the water, remain steady since chlorine degrades in water over time.

The flush involves opening up fire hydrants and allowing water to flow freely. It may look like wasting water, but it ensures that sentiment, chlorine, and other materials are flushed out.

During this short period of time, Fairfax Water switches from using combined chlorine to free chlorine as their primary disinfectant.

Most of the year, combined chlorine — or chloramines — are used to treat drinking water. Produced by a chemical reaction between chlorine and ammonia, it’s not as effective as free chlorine in disinfecting water, but it can stay in the water longer.

Free chlorine acts faster than combined chloring to break up sediment, but degrades in a shorter period of time.

The use of free chlorine can also lead to the water tasting and smelling funny.

So, if you are taking a big gulp out of the tap and it tastes like pool water, that’s why.

If you or someone in your household is particularly sensitive to this taste and smell, storing an open container of drinking water in the refrigerator will allow the chlorine to dissipate.

Drinking water does have a shelf life, though, so it should be switched out regularly.

At the levels used in drinking water, both combined and free chlorine are considered safe by the Centers for Disease Control and Prevention and Environmental Protection Agency .

All of this flushing began at the end of March and is expected to run until June 14 for most of Fairfax County.

Nearly 2 million people in Northern Virginia get their water from Fairfax Water, including nearly all of the county and the towns of Vienna and Herndon. It is Virginia’s largest water utility company and one of the 25 largest in the country.

Both Herndon and Vienna get their water “wholesale” from the company, meaning a third party or utility has the right to distribute water but not have the capability to treat their own water.

Herndon’s Department of Public Works does participate in the annual flush as well, opening up hydrants in both residential and commercial areas.

Fairfax Water also highly encourages commercial and residential property owners to flush their system if they’ve had to shut it down for an extended period of time during the COVID-19 pandemic. A thorough flushing is needed to clean out water that may have been sitting dormant in plumbing.

Water that remains stagnant for as little as two days can have mold, leeching, and other hazards in it that can lead to illness.

Photo via Rudy and Peter Skitterians/Pixabay