Boil Water Advisory – an advisory notice issued to notify users that boiling is required to render the water safe to use.
Do Not Drink Advisory – an advisory notice issued to users when actions other than boiling is required to protect them (e.g. lead or nitrate above acceptable levels). Other types of filtration and/or chemical or non-chemical treatment may be required (i.e. reverse osmosis).
Do No Use Advisory – an advisory notice that is issued to uses when boiling or treatment will not render the drinking water supply safe for users. The operator or operating authority may notify users of or provide users an alternate source of water.
Health Information Advisory – An advisory notice issued to inform specific community users of an exceedance (e.g. Fluoride or Sodium) and the recommended measures to be taken to reduce exposure and mitigate the risk to human health (i.e. the health unit may notify dental or  medical offices).
Precautionary Advisory – an advisory issued when there is work being done on a system or there is a possibility of contamination (e.g. main break) but an immediate threat to public health has not been identified. It is usually a boil water advisory.