Weather Affecting Spring Water Flush

(Updated at 10:25 a.m.) If you think this year’s annual spring water system flush is giving Arlington’s water a stronger than usual taste or smell, you’re right — and officials say the weather is actually playing a factor.

Just like every year since 2000, there are about six weeks in the spring when Arlington’s water is purified with chlorine instead of chloramine. In 2011, the chlorine level was downgraded from 3.7 parts per million to 3.0 parts per million because of a number of resident and staff concerns.

This year, however, some people have mentioned what they believe to be a stronger taste or smell to the water. Although the number of formal complaints so far hasn’t exceeded other years, ARLnow.com readers started a forum thread on the topic. One reader posted: “It’s overpowering and sickening. We’ve been clearing out the shelves of those 3-gallon jugs of water at Giant.”

Although the amount of chlorine has not changed, the cold weather appears to accentuate the taste and smell of chlorine.

“It’s a theory. Basically the warmer temperatures will generally use up a little more of the chlorine as it goes through the system,” said Dave Hundelt with Arlington County Department of Environmental Services. “We think, looking back, the reason we had so many complaints in 2011 was [the flush] started on February 1, when the temperatures were colder, and the chlorine was more noticeable. This year, we started a week earlier, during the third week instead of the last week of March. That combined with the temperatures in the region. They appear to be colder in the past few weeks than it was in March of 2012.”

Hundelt says as temperatures increase, the water warms up and the chlorine should be less noticeable. The temperature shift necessary to create a perceptible change in smell and taste is relatively small. Analysts are finding a stronger smell and taste when water temperatures are at or below 10 degrees Celsius (50 degrees Farenheit). Comparatively, water temperatures were around 7-10 degrees Celsius (about 44-50 degrees Farenheit) in Feburary 2011 when complaints poured in, but were at a balmy 16 degrees Celcius (about 60 degree Farenheit) last April.

Arlington’s water is purchased wholesale from the Washington Aqueduct, so much of the region experiences the same water conditions.

In addition to the chlorine change, each of the the county’s 3,500 fire hydrants will be opened for a short period to make sure the entire water system gets adequately flushed. That is too large a job to finish when the chloramine conversion ends on April 29, so residents may continue to see hydrants flushed into the month of May.

Anyone with major concerns about the water system, such as water main breaks, should call 703-228-6555 to report issues. More information about the switch from chloramine to chlorine can be found on the county’s website.