Lead testing results for water sampled by residents


Note: This article is from early Sep 2015. These results are from the first round of testing in Aug-Sep 2015. In total, we received 277 kits, of which 269 were deemed legitimate samples. The below analysis is for the first 252 samples received.


We analyzed all samples shipped to Virginia Tech from Flint to date. Flint residents returned an astonishing 84% of the sample kits we sent out (252 out of 300 samples). We thank our partners Water You Fighting For, Concerned Pastors for Social Action, ACLU of Michigan, Democracy Defense League and Flint residents for their dedicated efforts in maximizing sample kits being distributed, collected and returned to us in record time.

We will continue to analyze water samples as they are returned. However, mathematically, even if the remaining 48 samples returned have non-detectable lead, our conclusion will not change — FLINT HAS A VERY SERIOUS LEAD IN WATER PROBLEM.

Forty percent (40.1%) of the first draw samples are over 5 parts per billion (ppb). That is, 101 out of 252 water samples from Flint homes had first draw lead more than 5 ppb. Even more worrisome, given that we could not target “worst case” homes with lead plumbing that are required for EPA sampling, Flint’s 90%’ile lead value is 25 ppb in our survey. This is over the EPA allowed level of 15 ppb that is applied to high risk homes. This is a serious concern indeed. Several samples exceeded 100 ppb, and one sample collected after 45 seconds of flushing exceeded 1000 ppb.

We now advise Flint consumers to heed EPA information that advises consumers on how to avoid adverse health effects from exposure to excessive lead in drinking water. The main concern is related to water used for drinking or cooking. With the exception of one home that we sampled which had astronomical levels of lead, the levels of lead detected in Flint were safe for bathing, showering, toilet flushing and watering lawns/gardens.

Until further notice, we recommend that Flint tap water only be used for cooking or drinking if one of the following steps are implemented:

  • Treat Flint tap water with a filter certified to remove lead (look for certification by the National Sanitation Foundation (NSF) that it removed lead on the label), or
  • Flush your lines continuously at the kitchen tap, for 5 minutes at a high flow rate (i.e. open your faucet all the way), to clean most of the lead out of your pipes and the lead service line, before collecting a volume of water for cooking or drinking. Please note that the water needs to be flushed 5 minutes every time before you collect water for cooking or drinking. For convenience, you can store water in the refrigerator in containers, to reduce the need to wait for potable water each time you need it.

We do not issue this warning lightly, and note that our concern is based on several lines of evidence. First, scientifically, we predicted based on past research that the Flint River water chemistry would create a serious lead in water problem. Second, we confirmed the very high corrosivity of the Flint River water for lead in our laboratory testing at Virginia Tech. Third, for some reason that no one has yet explained to us, the Flint River water was introduced into the pipe distribution system without any measures (or even a plan) to reduce its corrosivity. We are therefore very perplexed by recent MDEQ assertions that the situation in Flint is normal. Finally, we have the results of our survey of 252 homes conducted with the assistance of Flint consumers. Because of the very serious and permanent health damage that arises from lead exposure, we feel that this problem requires immediate public health warnings and intervention– we provide that for Flint consumers in this report.

Another mystery that must be examined very carefully in the days and weeks ahead: How is it possible, that Flint “passed” the official EPA Lead and Copper Rule sampling overseen by MDEQ? In our experience, following the EPA site selection criteria targeting homes with the highest risk for lead, the MDEQ sampling should have found much worse results than our sampling. Instead, MDEQ is asserting that the lead levels in Flint are much lower. Hence, we call on the U.S. EPA and others, to conduct a detailed audit of the 2014 and 2015 LCR sampling round overseen by MDEQ in Flint, to determine if it was conducted consistent with requirements of the law.

From Our sampling of 252 homes demonstrates a high lead in water risk: Flint should be failing to meet the EPA Lead and Copper Rule

The chemistry of Flint River water is a type known to be highly corrosive to lead plumbing as well as iron pipe. Thus, when it was reported to Flint residents, that their water is meeting the EPA Lead and Copper Rule and is safe to drink, as scientists we were a little surprised. Because it is always possible that the current scientific understanding of lead corrosion is wrong, in the next few weeks we will be conducting several tests of Flint River water, to try and verify that Flint’s water is actually safe to drink.

Our efforts will include:

  • an audit of the sampling done by the city in 2014 and 2015, to see if there were obvious problems or irregularities with the sampling plan
  • resampling some homes sampled by the city, to see if their requirement to pre-flush the water 5 minutes the night before sampling, or using bottles with tiny openings@, is “missing” lead problems that are normally present
  • conducting laboratory testing to compare lead corrosion in Flint water versus Detroit water
  • work with Flint citizen scientists to sample at least 75 homes for lead in water (involves sending out 300 lead kits)


This report describes the results of lead sampling in Flint homes to date:

Before conducting this survey, we set a criteria to indicate whether there was a serious problem with lead in Flint water. Because we do not have records as to what Flint homes have lead pipe, we cannot test the “worst case” homes in Flint for lead, as is required for testing by the EPA Lead and Copper rule. According to EPA, if the “worst case” homes are tested and more than 10% are over 15 ppb lead, the city exceeds the Federal standards for lead in water.  For our sampling, which is of random houses in the city and not the worst case homes, if more than 10% of samples are over 5 ppb lead, we believe it indicates that the city has a very serious problem with lead in water. It is also important to remember, that there is no safe level of lead in water.

Of the 252 first draw# samples collected by Flint residents and analyzed at VT, 40.1% were over 5 ppb, which suggests a serious lead in water problem according to our experience and criteria. Forty two samples (16.7% of the 252 samples collected) also exceeded 15 ppb lead action limit, suggesting a very serious lead in water problem. That is, the Flint Citizen Science study to date, is finding results worse than the EPA standard which is applied to sampling “worst case” homes. The highest lead sampled in first draw so far was 158 ppb, and the highest sample after 45-seconds of flushing was 1,051 ppb. The 90th percentile lead level is currently 25.2 ppb, which is over the EPA standard applied to homes with “worst case” lead plumbing, and in a range where water consumption has caused lead poisoning in children and led to adverse pregnancy outcomes. Needless to say, these data are very worrisome, especially considering that our survey did not target “worst case” lead plumbing systems as is required for EPA sampling.

We are committed to informing residents on Flint water as soon as our data becomes available, and are also calling them . WE URGE CITIZENS TO CONTINUE COLLECTING SAMPLES, because we can draw stronger conclusions only when we have a higher number of them (samples). We also want to try and help Flint residents understand a) what wards of the city tend to have the most serious problems by mapping our results geographically across the city, and b) the types of plumbing systems that have the most serious lead problems.


Sample kits created at Virginia Tech = 300

Sample kits collected by Water You Fighting For? to date = 277

Sample kits mailed back to and received by VT to date = 252

Sample kits analyzed for lead to date = 252

Our goal for kit return to VT by mail = 75 kits

% of returned kits goal met = 336%

Threshold set to indicate problems with lead are not widespread: < 10% of samples over 5 ppb*

% of samples to date currently over 5 ppb = 40.1%, which is greater than our 10% criteria

90th percentile Lead = 25.2 ppb, which is over the 15 ppb EPA standard in samples analyzed to date

*If 10% of Flint samples in our survey are over 5 ppb, we believe that it indicates that Flint has a serious lead in water problem because our sampling event does not target “worst case” homes in the city. Sampling for EPA compliance requires that 50% of homes sampled have lead pipe and the other 50% have lead solder. We could not determine pipe material because we do not have access to city records.


Analysis: Dr. Jeffrey Parks, Anurag Mantha

Additional Help: Maggie Carolan, Christina Devine, Pan Ji, Rebekah Martin, William Rhoads, Siddhartha Roy, Min Tang, Alison Vick, Ni Zhu

Partners: ACLU of Michigan, Concerned Pastors for Social Action, Democracy Defense League, Water You Fighting For

Credits: Dr. Marc Edwards, Siddhartha Roy, William Rhoads


@Pre-flushing water for any amount of time prior to testing, and use of bottles with tiny necks during sampling increases the risk of missing actual lead problems that might be occurring in the water. A stagnation time of at least six hours is, therefore, recommended where water has not been used in a home at all.

# Sampling is conducted by collecting the first 1L of water from the tap at normal flow (dubbed “first draw”) to identify any lead accumulation in the water. Subsequent samples are taken after 45 seconds and 2 minutes at the same flow rate to test whether water from the distribution system contains lead as well, and if flushing prior to use can lower the likelihood of exposure.