City officials advised residents living in the Highlands neighborhood of Post Falls to boil their water after a second set of tests confirmed Wednesday the water supply is contaminated.
The first sign of a problem came Tuesday when results from three of 10 tests taken Monday showed coliform in the water serving the Highlands area, according to Terry Werner, Post Falls water superintendent.
More samples were taken Tuesday, and the results showed two samples still were contaminated.
“At this time, we do not know what’s causing it,” Werner said Wednesday.
Coliform bacteria aren’t necessarily a health threat, but they do indicate a problem with the water system and the possibility that more harmful organisms could have entered the water.
Tests for E. coli bacteria came back negative. Water samples from the rest of the city came back clean.
Werner said this is the first time the city has had to issue a boil-water advisory. The city routinely takes 10 samples a month on its water system.
The Highlands reservoir serves 137 households. Those residents should boil their water before drinking until they get word that the problem has been resolved.
“We’ll be doing some flushing of the system, possibly some chlorination of the system” to get rid of the bacteria, Werner said.
The boil-water advisory does not apply to Highlands residents who are not on the city’s water supply.
The Bayview Water and Sewer District also issued a boil-water advisory this month after a strain of E. coli bacteria was found in its water supply.
The district switched wells and chlorinated its water to resolve the problem.