All Jersey City residents are being advised to boil their water before use after an “irregularity” was found in the water supply.

The advisory is in place until at least Saturday afternoon.

Mayor Steven Fulop said on Twitter, “We do regular testing, there was an irregularity isolated near Christ Hospital yesterday. It subsequently tested OK, we then test upstream/downstream which we’ve been doing - Until all test results come back OK, we’re advised to implement a boil advisory.”

Fulop says that test results should be returned by 5 p.m. Saturday.