Lead and copper in Iowa drinking water systems

Lead is a naturally occurring metal used in a wide variety of products, such as ammunition, batteries, gasoline, paint, and plumbing pipes and solders. Today, the major ways people are exposed to lead are through ingesting dust, soil, or paint, and drinking water. Lead in water lines and household plumbing materials can enter drinking water without any noticeable change in smell, taste, or color. The United States (U.S.) Environmental Protection Agency (EPA) regulates lead in drinking water through the Lead and Copper Rule (LCR), which was put into place since 1991. However, lead-in-water crises, such as those that occurred in Newark, New Jersey, Flint, Michigan, and Washington, DC, have raised public attention to the risk of drinking water with lead in it and set the standard on improving the federal regulations. Currently, the U.S. EPA is revising their lead regulations (Lead and Copper Rule Revisions), so now is the time to act.

In this dissertation, I focused on weaknesses in the LCR from a data-driven standpoint to help inform revisions to the LCR. I estimated the number of consumers on public water who are at risk for drinking lead in Iowa. I found that, annually, about 113,000 people are at risk for drinking lead in their tap water above the World Health Organization’s (WHO) drinking water guideline (10 parts-per-billion or ppb of lead). This level of lead is also the proposed trigger level for specific action in the LCR Revisions.

These risk estimates made me wonder just how many more homes could be protected under the LCR if we applied more stringent requirements in lead regulations. To explore this idea, I took a closer look at the 90th percentile approach used by water systems to comply with the LCR. This approach allows for up to 10% of homes tested in a community to have elevated lead levels without any additional action or public notification needed. I found that including the few additional homes that make up the 95th percentile approach, or only up to 5% of homes allowed to have elevated lead levels, causes a 5-fold increase in the number of LCR reports made by water utilities that would require regulatory action.

As my graduate studies advanced, I realized only focusing on regulatory action geared towards the water utilities will not protect the public from lead in drinking water. Consumers of public and private water also have to act to reclaim their confidence in their drinking water. To help consumers gain confidence in their drinking water, I, along with colleagues, created a statewide drinking water testing program in Iowa. We have tested over 500 homes for lead and copper, providing Iowans with the means to take control of their tap water. Of the 558 homes we tested, 16 homes had lead levels greater than the WHO drinking water guideline of 10 ppb. Seven of these homes have retested their water with us to pinpoint where the source of lead was in their plumbing and seek advice on how to remediate it. Notably, we noticed that the method of measuring lead in water is critical to ensure all of the water lead exposure has been caught. In addition to laboratory testing, we also investigated the usefulness of a low-cost and commercially available lead-in-water test that a consumer could conduct in the comfort of their own home.

Clearly, even in the absence of a lead-in-water crisis, such as the switching of water sources in Flint, Michigan, a significant number of people in Iowa are at risk from lead concentrations exceeding the WHO guideline as well as several other lead guidelines. Our results highlight the need for more consumer- or resident-based lead-in-water policies and avoidance strategies as well as more stringent regulation of the LCR to ensure public protection.