Dirty water in the vicinity of Parliament House and the Parliamentary Library in Wellington triggered a warning to staff not to drink tap water.
An email sent out earlier today advised not to drink it as a "precautionary measure" because of an external issue.
"The Buildings and Safety team is investigating with Wellington City Council. The team will provide an update when the water is suitable for drinking again."
But there was no reason provided for the sudden warning.
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Wellington Water's drinking water chief adviser Laurence Edwards has since confirmed they responded to reports of dirty water being experienced in the buildings at about 11.30am.
"No maintenance activities were being carried out within the public network nearby at the time that could have been potential sources", Edwards said.
"Subsequent checks of water quality in the public network and from within Parliament Buildings indicated no cause for concern."
The water has been deemed safe to drink.
Edwards said one possibility for the dirty water is a period of high usage stirring up low levels of sediment within the pipe work.
"In the unusual event of discoloured water being experienced we recommend people flush their taps until the water becomes clear."
Bottled water was available from the ground floor lobby of Parliament House this afternoon.