The proportion of homes in New York City with elevated lead levels in their tap water is back to normal, city officials said this week, but all residents are still urged to run their tap water for at least half a minute before drinking or cooking with it.

City officials said the latest round of sampling, conducted from Jan. 1 to June 30 in older homes known to have lead service lines or lead solder in pipes, showed that only two out of 114 samples had elevated levels of lead. At less than 2 percent, that is well below the 14 percent found in testing last year.

The city Department of Environmental Protection is still investigating the cause of last year’s elevated level but says it may have been caused by fluctuations in the water’s pH or acidity levels, which can make water more corrosive.



The department conducts such tests under the federal Safe Drinking Water Act, which requires water utilities to test annually for lead and to notify the public if results show that more than 10 percent of water samples exceed lead levels of 15 parts per billion. Excess lead in drinking water can cause health problems, including physical and mental developmental delays in infants, health officials say.

Because of the potential risks, the city’s Run Your Tap ad campaign, which started last November, continues. Officials recommend that residents run their taps until the water gets cool — for at least 30 seconds — before drinking it, cooking with it or using it to make baby formula if the faucet has not been used for several hours.

The next round of testing is to be completed by the end of this year. To increase the sampling pool, the city is offering a $25 credit on water bills to homeowners with lead services lines or lead plumbing.

The city also offers free lead testing,something that I tried out last year and wrote about here in a Green post.