Given the vital significance of water to human survival, public water suppliers are depended upon to deliver safe drinking water. The Safe Drinking Water Act (SDWA) attempts to realize this purpose by creating standards that public suppliers must satisfy in providing water to communities or municipalities. Under one standard, public suppliers must filter their drinking water if they fail to satisfy certain safety criteria. Whether or not to construct a filtration facility in Metropolitan Boston has spawned a conflict between the Environmental Protection Agency (EPA) and Massachusetts Water Resources Authority (MWRA). EPA insists that MWRA construct the filtration facility, while MWRA asserts that other less costly alternatives are available. This Comment explores the foundation of the SDWA as well as the relevant regulations, discusses the claims posed by both EPA and MWRA regarding filtration, and ultimately concludes that MWRA's position is more sensible.