New tests from the team at Virginia Tech show Flint’s water is “highly variable” and still not safe to drink without a filter.
Marc Edwards says tests done last month show Flint’s water is still above the federal action level for lead.
More from their press release:
Thus, virtually all homes in Flint must be considered at risk, at the present time, for elevated lead in water, unless the homeowner is certain that there is no lead plumbing (i.e., lead service line, leaded brass, or lead solder) in the home. This means that homes that may have tested very low for water lead in past sampling efforts, must be considered at risk for high lead in water—the advice to use bottled or filtered water, applies to all homes, regardless of past testing results.
Virginia Tech's research is the only test that is a "before and after" look at the water system.
The team tested 269 homes last year to show the city had a problem while the city was using the Flint River as its water source. After the city switched back to Lake Huron water from Detroit, the team tried to retest those same homes and received 174 samples.
Comparing those results, the team found that the 90th percentile lead level did go down in the city, but it is still above the federal action level for lead (15 ppb).
Again, more from their press release:
The 90%’ile lead level in the March 2016 sampling event was 23 ppb which is above the 15 ppb EPA 90%’ile action level. Because the pool of 174 homes sampled is random in terms of the home plumbing profile, and was not selected to include at least 50% homes with lead pipe as required by the EPA for Lead and Copper Rule (LCR) monitoring, our reported 90%’ile lead is probably lower than that which would be determined in an approved LCR sampling event. Hence, in our opinion, Flint water is not yet meeting the action level.
Edwards recommends that residents continue to use bottled water, or filtered water, for cooking and drinking until the emergency is declared over.
Water needs to move through the system
The water in Flint now has corrosion control chemicals added, but those chemicals are not being spread throughout the entire system.
Edwards says people will need to use more water to speed up the recovery of the distribution system, so that corrosion control treatment can work.