A Precautionary Boil Water Advisory (BWA) is a public statement advising customers to boil tap water before consuming it. Precautionary advisories are issued when an event has occurred allowing the possibility for the water distribution system to become contaminated. An advisory does not mean that the water is contaminated, but rather that it could be contaminated: because the water quality is unknown, customers should assume the water is unsafe to drink and take the appropriate precautions.
An advisory is different from a Boil Water Notice, which is issued when contamination is confirmed in the water system. During a notice, all customers must boil their water before consuming it or use bottle water.