Comparing the economic, environmental, and exposure impacts of options for coming into compliance with drinking water regulations in very small water systems in the US

Abstract Very small drinking water systems in the United States can face challenges in complying with the Safe Drinking Water Act, resulting in a need to improve existing infrastructure. This study applied a triple bottom-line approach to compare modeled health, environmental, and economic impacts of improving existing centralized water treatment systems to using point-of-use/point-of-entry (POU/POE) devices in four very small community water systems (CWS) serving 40–450 people. We found that POU/POE systems could be implemented 1–3 years faster than centralized improvements and achieve higher removal efficiencies (up to 99% removal for arsenic, compared to 80% for some centralized options), resulting in larger decreases in human exposure to arsenic or nitrate. Treatment options using adsorptive media or ion exchange resins had larger overall environmental impacts than reverse osmosis devices, and the total 30 year cost of POUs/POEs were more expensive in 3 of the 4 modeled systems than centralized improvements due to high replacement frequencies and populations. An ‘ideal’ option in each CWS was not selected; rather, we contextualized our results as tradeoffs.