Small Drinking Water System Variances
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A small system variance enables a public water system to utilize a treatment technology that achieves the maximum removal of the contaminant that is both affordable and protective of public health, but does not remove the contaminant to the degree specified by the drinking water regulation. States may grant small system variances only for those drinking water standards that EPA has determined are unaffordable for one or more categories of small systems.
To date, EPA has found its new and existing non-microbial drinking water rules to be affordable. Therefore small system variances have not been available for states to issue to small systems. For future non-microbial contaminant rules, EPA will evaluate the need for small systems variances based on affordability analyses.
Under the Safe Drinking Water Act (SDWA), small public water systems (PWSs) are broadly characterized as systems serving 10,000 or fewer customers. This category of systems represents more than 92% of the nation’s 51,000 community water systems (CWSs), and nearly all of the 100,000 non-community water systems. SDWA further breaks down small systems into those serving 3,301 – 10,000 persons, those serving 501 – 3,300 persons, and those serving 500 persons or fewer.
Some small systems face unique financial and operational challenges in providing drinking water that meets EPA standards. To address these challenges, EPA encourages and supports utilization of small system compliance and sustainability tools to strengthen and target financial support to small systems, including working with United States Department of Agriculture Rural Utilities Service, strengthening capacity development tools and promoting restructuring of non-sustainable systems.
does not reduce a contaminant to the level required by the regulation,
is affordable, and
is protective of public health.
States do not have the authority to grant small system variances from national primary drinking water regulations unless EPA makes two determinations at the time it promulgates the regulation. First, EPA must determine for small systems of a similar size and with similar source water that there are no affordable technologies available that achieve compliance with the standard. Second, EPA must also determine that there are affordable variance technologies available that are “protective of public health.”
any contamininant MCL or treatment technique promulgated prior to January 1, 1986; or
for microbial contaminants.
- list technologies for small systems that meet the Surface Water Treatment Rule;
- issue a list of technologies that achieve compliance with the MCLs or treatment technique requirements for other existing NPDWRs; and
- issue guidance or regulations for variance technologies for the existing NPDWRs for which a small system variance can be granted.
EPA should consider the household cost of each new regulation on an incremental basis rather than a total cost of all water treatment regulations, and
EPA should consider reducing the current affordability threshold.
Links to the two reports are below:
- Affordability Criteria for Small Drinking Water Systems: An EPA Science Advisory Board Report - December 2002
- Recommendations of the National Drinking Water Advisory Council to U.S. EPA on Its National Small Systems Affordability Criteria - July 2003
In 2006, EPA published a Federal Register notice to request comment on revisions to EPA’s national affordability methodology for small drinking water systems and a methodology for determining if an affordable variance technology is protective of public health. The proposal described a number of options for revising the affordability methodology for public review and comment.
Federal Register Notice: Small Drinking Water System Variances – Revision of Existing National-Level Affordability Methodology and Methodology to Identify Variance Technology that is Protective of Public Health