The institute’s regional rental data, released this week, reported the median weekly rent for units in Greater Bunbury had increased to $290.

The overall median rent and median weekly house rent remain steady at $300, with the vacancy rate also stable at three per cent.

Harcourts Bunbury principal Richard Morgan said they had seen a general increase in rental prices over the last few months.

Mr Morgan attributed the increase to demand for rental properties from professionals drawn to the region to work on projects such as the desalination plant, as well as increased interest rates prompting people to rent rather than buy.

"We have noticed the availability of rentals drop off in the last month especially, which is unusual as we go into June," he said.

However REIWA director of research Stuart Darby said the median unit rent was more volatile than housing rent due to the composition of the unit market, which spans from low-rent properties to high-end apartments.

The median weekly rent for units in Bunbury fluctuated between $265 and $295 last year.