By Dave Linville, Vice President and General Manager, AquaSmart, Inc.
Throughout human history, lead pipes have been used to carry drinking water. In the US, it wasn’t until the 1980s that this practice was reconsidered for its potential harmful effects on humans. The original Lead and Copper Rule (part of the US Safe Drinking Water Act) was implemented in 1993, creating maximum concentrations of lead in drinking water.
In the late 1990s, in addition to setting maximum lead concentrations, the United Kingdom mandated the use of phosphoric acid to control lead corrosion in drinking water supply pipes. A minimum dose of 2.0 mg/l of phosphorus was required until utilities could prove lower concentrations were effective. Most utilities currently dose between 1.5 and 2.0 mg/l as phosphorus as a result of corrosion optimization studies.
Last decade, tens of thousands of residents of Flint, Michigan, were exposed to dangerous levels of lead (and other chemicals), which elevated public concern about lead poisoning from water. In response, the US EPA began the process of revising the Lead and Copper Rule, which goes into effect in 2024. An expected outcome of the 2024 rule revisions is an increased use of phosphoric acid for lead corrosion control in drinking water in the US. Wastewater treatment facilities, the phosphorus supply chain, and many aquatic ecosystems in the US are likely to be impacted as a result. After all, drinking water often becomes wastewater, carrying the phosphorus downstream.
In 2014, a study was conducted to predict the impact on the Chesapeake Bay watershed if higher levels of phosphorus (such as currently used in the UK) were used for drinking water corrosion control in the US, and it found: