Dozens more people were potentially exposed to asbestos during work on a Water Corporation project in WA, the State Government has said.

Water Minister Mia Davies told State Parliament this week that 138 people could have been exposed to asbestos while conducting maintenance at a reservoir near Wyalkatchem this year.

The number is 50 higher than the 88 people originally thought to have been exposed to the tank containing asbestos.

The early estimates included both Water Corporation staff and contractors, but Ms Davies says that was not all.

The Water Corporation reportedly began an investigation when the problem was first revealed.

It continues to claim that the health risk to workers is “relatively low’.

Ms Davies says there are additional affected people.

“We have taken time to make sure we have cast a very broad net to ensure everyone that may have had an involvement or interaction in that site is availed of the information the Corporation is providing and that they are offered assistance,” she told Parliament.

“There is unfortunately an increase in the numbers from when we first spoke about this in this place but it has been a result of a very thorough and ongoing investigation into how this came about.

“In the interim [while the investigation is ongoing] the Water Corporation is looking at their other sites, making sure they are putting in place mechanisms to prevent this from happening again.”

The Water Corporation has been forthcoming with details, with a spokesperson saying investigations so far had only revealed that the processes for dealing with asbestos on the site were “not adequate”.

“It has also identified opportunities to deliver improvements in the management of asbestos across its business,” the spokesperson said.