Source: Rockhill Environmental/NECC Newsletter
A plumbing contractor installing a lawn sprinkler system did not install adequate vacuum breakers on the discharge side of the water supply valves. When pressure in a drinking water system fed by the same water main fell below atmospheric pressure, a vacuum was created which caused back-siphonage of stagnant water from the lawn sprinkler system into the drinking water supply. Several people drank from the water supply and contracted dysentery. Costs were incurred to investigate the issue, purge the system and to provide temporary clean water. Suits followed alleging bodily injury.