A city beach is being proposed for the Riverbank precinct in the Adelaide CBD, with plans to have it in place by summer.

But the South Australian Liberals say the Government needs to get its priorities straight and focus on erosion issues at metropolitan beaches.

Tender documents reveal bids are being sought by the urban renewal authority, Renewal SA, for design and installation of a beach on the banks of the River Torrens at the northern end of the CBD.

The tender document says Renewal SA wants "an urban beach demonstration project in the Adelaide Riverbank from November through to January" and has a budget of about $180,000.

"There will be a variety of sand and water-based activities for adults and children alike, run during the day and night, including high-quality food and beverage offerings and a program of 'participation opportunities'," the tender said.

The Opposition's environment spokesman, David Speirs, slammed the State Government's plans saying it should first focus on metropolitan beaches that are losing tonnes of sand each year.

"We know the Adelaide Living Beaches program has failed. We have got huge amounts of erosion. Storms of recent date have caused further erosion," Mr Speirs said.

"We are calling on the Government to get your priorities right and deal with the metropolitan beaches before you go and build a new trendy beach in the city."

He said it was ludicrous a beach would be built next to water that people can't swim in.

Water activities to draw people to CBD

Infrastructure Minister Stephen Mullighan said the State Government had already invested more than $5 million in metropolitan beaches.

"Both the sand pumping and sand carting effort continue periodically," Mr Mullighan said.

"People will form their own judgement about the sort of water activities they will participate in.

"What we're hoping to do is get more people out into the Riverbank precinct … It good for people to be using what is one of the best part of the CBD."

But the idea to build a beach at the Torrens is not new.

In the early history of the state, and well into the 20th century, swimming competitions in the Torrens were an annual fixture on Adelaide's social calendar.

At the swing bridge over the Torrens in Gilberton, you can still see the remains of the old swimming pool which was a feature of the suburb for years.

Mr Mullighan said similar city beach ideas had been successful in areas like Port Adelaide as well as in interstate and overseas cities.

"We need to be activating our city as much as possible to give people who live in Adelaide a variety of things to do to get them out and about and spend money at local businesses."

The closing date for bids is September 1.