New York City has recently stated an adjustment to its procedure for testing the water supply of schools for dangerous lead levels. This new procedure is being implemented after experts said the methods that were being used could lower the levels found.
The night before the samples were taken the contractors would let the water run from all outlets for two hours. This is a practice known as pre-stagnation flushing which can lead to lower than normal lead levels in samples. The Environmental Protection Agency does have voluntary guidelines for testing the water in schools that do not mention pre-stagnation flushing.
A Spokeswoman for Mayor Bill de Blasio stated that in the future the city will try to test the water as much as possible while school is in session and not on Monday mornings. Starting in October the city plans to retest every building that had over 15 parts per billion of lead.