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Public Health - Seattle & King County

What to do when a boil order is issued

What is a boil order?

A boil order is a notification made by the Office of Emergency Management, water system operators or regulators, or government departments advising people who share a water source that the water is contaminated with bacteria. This order advises people to boil the contaminated water prior to using it in order to make it safe for drinking. Public notification of the boil order is made to ensure that every water user on the affected system has knowledge of the contamination.

How is it determined that a boil order is necessary?

A boil order is issued based upon (but not limited) to the following criteria:

  • Presence of fecal coliform;
  • Evidence of a suspected source of contamination;
  • Coliform contamination of source;
  • Signs of flood water near or over the source of supply.
Boil order instructions
  • Strain the water through either a cheesecloth, coffee filter, or other clean, porous material to remove as many solid particles and dirt as possible;
  • Bring the water to a rolling boil for 1 minute;
  • Let the water cool. Pour into a container that has been boiled or sanitized with chlorine bleach;
  • To preserve the quality of the water, refrigerate the water until use.

See also: "How to prepare safe water after a disaster"