Staff, patients and visitors have been advised to avoid water at Princess Margaret Hospital in Christchurch after it was found to be contaminated.

Staff, patients and visitors are unable to drink the water at a Christchurch hospital after it was found to be contaminated with E coli.

In an email to Princess Margaret Hospital staff on Sunday, the Canterbury District Health Board (CDHB) said people should avoid drinking the water until further notice.

"Everyone on the site should use bottled water where possible and do not use zips or plumbed in water coolers until further notice," the email said.

CDHB chief of psychiatry Dr Peri Renison said on Monday evening the water supply had since tested negative for contaminants and no-one had been harmed.

READ MORE:

* Derelict state of Princess Margaret Hospital blamed for health care issues

* The sick ironies of Princess Margaret Hospital

* Delays to rescuing services stranded in damaged hospital

However, it would not be cleared for drinking again until the results of a third test were available, likely later this week, Renison said.

Renison​ said the E coli was found during routine water testing of the hospital's private water supply.

Staff had been asked to bring in their own personal supply of water from home to stretch a "limited" supply.

"We are providing bottled water and are treating the site's water supply with chlorine," Renison​ said.

Renison would not say how the water was contaminated or how long it had been contaminated for.

The hospital, in the hillside suburb of Cashmere, has been blamed for many care issues, prompting calls to fast-track a new mental health facility.

It was supposed to be decommissioned and sold last year.