Those working at Parliament House and the Parliamentary Library in Wellington have been told not to drink the tap water there until further notice.
An email has been sent out advising of the "precautionary measure" due to an external issue.
"The Buildings and Safety team is currently investigating with Wellington City Council. The team will provide an update when the water is suitable for drinking again."
Bottled water will be supplied to occupants of the two buildings if the issue cannot be resolved in a timely manner, the email said.
Wellington Water and Wellington City Council have been approached for comment.
While it's unclear exactly what the issue is related to, it wouldn't be the first time Wellington's water woes have affected those working in and around the parliamentary precinct.
In April, Ministry of Health staff were sent home from work after a water main burst on Molesworth St.