The Associated Press

Lead Sampling Test Results


This data was distributed in early April 2016 for a story published on April 9, 2016. Nearly 1,400 water systems that serve 3.7 million Americans have violated the federal lead standard of 15 parts per billion at least once since Jan. 1, 2013. Those include 278 systems that exclusively serve schools and daycares in nearly every state, some of which reported lead at dangerous levels and among the highest in the nation.

NOTE: The EPA on April 7 updated its data online, to go through the end of 2015. The AP data encompasses only the sample results from 1992 through 9/30/15. The spreadsheets were last updated by the AP on 4/8/2016 with corrections to one Montana sample result.

About the data set

The data set, which includes results of sampling tests through September 30, 2015, summarizes lead sampling results from the EPA's Safe Drinking Water Information System. Be aware that these results are self-reported by water systems and there are some extreme outliers in the data which may have resulted from input errors. The AP analyzed 25 years of sampling data reported by roughly 75,000 drinking water systems that are subject to the lead rule, which went into effect in 1991. The data used in our analysis is current as of the end of the third quarter of 2015.

While no lead exposure is considered safe, the rule calls for water systems to keep lead levels below 15 parts per billion. If more than 10 percent of sampled high-risk homes are above that level, water officials need to inform customers about the problem and take steps to address it, such as by adding corrosion control treatment to keep lead from service lines from leeching into the water. Samples are taken at taps at residential, commercial and government sites - the number of samples required is based on how many customers the water system serves.

Our analysis includes only the water systems that are currently active, have a current customer count above 0, and have been sampled since the beginning of 2006. We deleted duplicate records of samples that covered the exact same sampling period with the same results.

The EPA's SDWIS lookup tool for Lead and Copper samples is here. You can use this tool to check on all sampling results from your local water system -- enter your local system's Pwsid from the attached lead sample file into the "PWS ID" field and delete the Sample End Date, then click on "View Reports" to see all samples taken at your local system. PLEASE NOTE: The samples reported on the EPA's website are expressed in milligrams, not micrograms (parts per billion). To get the proper ppb level, multiply the EPA site's results by 1,000. If this number is over 15, it is over the action limit. (This should also then match the spreadsheet numbers, which are properly recorded in parts per billion).

ALSO NOTE: The EPA on April 7, 2016 updated its data online, to go through the end of 2015. Because of this, if you use the online lookup tool you might find more recent results -- or, in a small number of cases, a corrected result for a previous test.

For more information about how agencies conduct water samples, see this EPA guide.

Included spreadsheets

Over-limit Water Systems: The first spreadsheet includes the nearly 1,400 water systems that reported a sample result above 15 ppb in the past three years (sample start date: 1/1/2013 or later). The AP spot-checked a handful of extreme outliers, and has corrected results of samples in those determined to be incorrectly reported. Other outliers remain in the data but may also be erroneous; please treat extremely high results -- anything over 50 ppb -- with some suspicion and double-check accuracy with your local water system.

Download the over limit file: here

All Water Systems: The second spreadsheet provides data on all the water systems that have been sampled for lead since Jan. 1, 2006. This includes the name of the water system, city and state, the dates of the most recent sampling period, the sample results at the 90% benchmark, and the total number of times the federal limit of 15 ppb has been exceeded since 2013 and since sampling began in late 1991. Extremely high results (above 50 ppb) should be double-checked with the agency for possible errors in reporting.

Download the entire lead sample file: here


This data is reported to the EPA by state enivornmental agencies. There are some issues with misplaced decimals in the sampling data, and extremely high results should be regarded with suspicion. A spot-check of some of the largest outliers in the dataset found that most had a decimal-point error. In the cases where the AP found an error and received the actual sampling results, the data has been corrected (these changes were made in the case of five water systems). Please call the water system involved to double check before reporting results that are many times over the federal limit.

The state and city is where the administrator of the water system is located. In nearly all cases, these are the same as where the water system is located. In some cases, a water system may serve customers in multiple states. And in the case of multi-state companies - or very small systems - the administrator may be off-site.

The EPA on April 7, 2016 updated its data online to include sampling results through the end of 2015. Because of this, if you use the online lookup tool you might find more recent results -- or, in a small number of cases, a corrected result for a previous test.

In addition, some water systems, including in Flint, have also been found to manipulate the lead sampling tests -- dropping samples above a certain level, for instance -- to avoid hitting the federal action limit of 15 ppb. For information about how Flint dropped some samples, see here.

Other water systems have been criticized for not taking samples from high-risk areas. For more on this, see this.

PROBLEM DATA: The GAO has found problems with states' ability to accurately report water quality data to the EPA. For more details, read this.

Column Definitions, Over-Limit Water Systems

Column Definitions, All-lead-samples

All data collected and prepared by AP Data Journalist Meghan Hoyer.