Some Tasmanian public servants have been forced to rely on bottled water, after contamination was found in the water supply of their Hobart office buildings.

In December last year, staff at St Johns Park in Hobart were instructed to stop drinking tap water in their offices following the discovery of high levels of lead, copper and nickel in the supply.

CPSU spokesman Tom Lynch says it is far less than adequate for a modern workforce.

“It's a rundown site, it has been for a long time and I think it is an indication of the value that's placed on the services that are being provided out there,” he said.

Government staff in the buildings include child protection workers, and alcohol, drug and mental health support staff.

“They should be purpose-building accommodation for vital services like child protection and disability services, and I challenge all political parties to come up with funding for that over the next term of government,” Mr Lynch said.

Despite the contamination being above Australian Drinking Water Guidelines for copper, lead and nickel, the Department of Health and Human Services (DHHS) has downplayed the issue, saying the problem was “in areas that were unoccupied, or not used by staff for drinking purposes”.

“Results from sampling in staff amenities and kitchenettes met guideline values,” a spokesperson said.

“Work was undertaken early this month [January] to flush all kitchen systems, along with those that returned elevated readings, and further testing is being undertaken. These results will guide strategies to rectify the issue.

“Public Health Services and consulting engineers are working with DHHS to understand and address the situation.”

Mr Lynch said the facilities could be contributing to a serious understaffing in child protection.

“This is why we've had a problem filling positions at child protection for the last three or four years,” he said.

“The Government does everything to disincentivise people working there.”