The U.S. Environmental Protection Agency (EPA) defines small drinking water systems as serving 10,000 people or fewer. These systems have a number of challenges that their larger counterparts typically do not. These can range from financial resources to a lack of technical expertise or managerial capacity. Also, because small systems largely draw from groundwater sources whereas large systems often pull from surface waters, nitrate is more prevalent in small systems than large systems, frequently occurring in quantities above the maximum acceptable limit. While perchlorate is a different contaminant with no current Federal limit, it, too, can be a concern. Because both contaminants can be removed by the same treatment processes, Abt and EPA produced this article to identify the costs of different removal processes to help the managers of small drinking water systems determine how they can best address these contaminants. Their findings demonstrate that some lesser-used processes can be more cost-effective.