The N.W.T. government is asking people in Hay River, Enterprise, Kakisa and on the Kátł'odeeche Fırst Natıon reserve to boil their water for at least one minute before drinking it.
These communities had boil water advisories issued and lifted a few times this summer.
The latest boil water advisory was announced in a news release Wednesday, and the N.W.T. Health Department says it's "precautionary." It's due to a reoccurrence of "higher than normal" turbidity, or muddy water, states the news release.
There hasn't been any illnesses due to the drinking water reported in the communities, says the department.
All water used for drinking, preparing food, hot and cold beverages and ice cubes, as well as for washing fruits and vegetables, and dental hygiene must be boiled.
It's particularly important to boil water used to prepare infant formulas, and to not drink from public fountains, the news release states.
It is not necessary to boil water used for other household purposes; it's also OK to shower, bathe or wash using tap water, but avoid swallowing the water.
The release also states that "Brita" type drinking water filters, which use activated carbon filters, are not a safe method for treating water during a boil water advisory, as they do not disinfect the water.
The government says its chief environmental health officer will monitor the situation, along with the Town of Hay River.