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Ellsworth Sourcewater Protection Plan, Appendix B December, 2004 Page 45 of 63


Emergency Response Information for Public Water Systems Principle Statement

This information should serve as a guide to public water supplies in the event of a drinking water emergency. Its intended uses are to protect the health of water system consumers, maintain fire protection and to assist utilities in preparing emergency response plans. The plan should be used in instances where drinking water emergencies have occurred.

Drinking Water Emergencies

Drinking water emergencies can result from many circumstances. Main breaks, loss of electricity, pump failure or contamination of a source can all cause detrimental impacts to a public water system. Without a plentiful supply of potable water, the health and welfare of the general public is jeopardized, fire protection systems are compromised and businesses are impacted.

Backflow Conditions

Water outages can be caused by a loss of electric power to primary pump systems, main breaks or other conditions which force manual shutdown of drinking water supplies. The loss of system pressure in a water system can create backflow conditions. Backflow conditions can siphon water from homes, businesses or factories into the water supply. A good backflow prevention program is the best safeguard against this type of contamination. One of the most common contaminants caused by backflow conditions is coliform bacteria. Therefore, drinking water quality is assumed to be compromised after a distribution system has been dewatered. Systems which are dewatered are placed on a Boil Water Order.

After water pressure has been restored throughout the system and the system operators are confident that conditions have stabilized, resampling must be conducted to verify that water is safe for consumption. The Drinking Water Program must resample all non-community water systems and all community water systems that serve less than 500 persons. Community water systems that serve populations greater than 500 persons may conduct their own resampling. The Drinking Water Program’s Boil Water Order policy can be found in Appendix A. Information is provided concerning conditions that require a Boil Water Order, how to remedy the conditions and how to remove a Boil Water Order.

Boil Water Order Policy Deficiencies Requiring a Boil Water Order

  • 1.

    Acute bacteria violation (fecal and/or E. Coli present - issued after recheck samples are taken).

  • 2.

    Turbidity MCL violation (turbidity above 5.49).

  • 3.

    Unchlorinated surface water entering system.

  • 4.

    Unfiltered surface water entering system from an emergency back-up source.

  • 5.

    System without water or with negative pressure zones (see attached flow chart).

  • 6.

    No working chlorination and repeated nonacute bacteria violations.

MRWA Contingency Plan Template 4/03

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