Surface Water Treatment Rule

If a public water system uses a lake, river, stream or pond as it's water source, then it is regulated by the Surface Water Treatment Rule.

Round Pond, drinking water source for Vinalhaven, ME

Round Pond is the source of drinking water for Vinalhaven, Maine. The Vinalhaven Water District is managed by Aqua Maine, Inc.

The Surface Water Treatment Rule (SWTR) was published in the Federal Register by the Environmental Protection Agency on June 29, 1989. Significant revisions were ordered in August, 1996, when the Safe Drinking Water Act was reauthorized by Congress. This rule contains provisions that require disinfection and filtration for all public water systems that use surface water or a source that is ground water under the direct influence of surface water. Only those systems that were able to demonstrate compliance with the stringent source water quality criteria, meet the inactivation (contact time) requirements, and maintain an effective watershed control program obtained an avoidance to filtration. The State of Maine has thirteen (13) community water systems that qualify for filtration avoidance. The SWTR Specialist and regional field engineer annually inspect the unfiltered system's disinfection facilities, operations, and the on-going source protection efforts.

The rule established Maximum Contaminant Levels (MCLs) for Turbidity, Heterotrophic Plate Count (Bacteria), Giardia Lamblia cysts, Legionella, and enteric viruses. The SWTR also published approved testing methodologies for the purpose of determining compliance. Approved testing procedures can be found in the Standard Methods text or 40 CFR Part 141. The monitoring requirements are dependent on the type of filtration and/or disinfections treatment employed by the system.

Alternative Filtration Technologies Guidebook

Contact Time Determination

Contact Time Tables for Giardia Lamblia Inactivation (.pdf format)

SWTR Policies

(available in .pdf format - Click to download a free copy of Adobe Reader)

If you have questions about the Surface Water Treatment Rule or Approved Alternative Filtration Technologies, please contact your Compliance Officer.