Revealing full details of their proposals for the first time, the Splashback group said they planned to create a soft-play area at the centre, and open for an extra day each week to bring in much-needed extra revenue.
Waterworld shut its doors in January after council chiefs said they could not afford the £340,000-a-year subsidy.
However, the Splashback campaigners persuaded the council to halt the sale of the site so a community-based alternative could be explored,
Today, the group said they proposed buying the ground lease for £1 and then introducing a series of changes to bring the subsidy down well below the Scottish average of £2.18 per visit.
Johnny Gailey, a leading member of Splashback, said the group’s proposals would reduce the subsidy to £273,000 in the first year of operation, and by year three to £223,000.
The turnaround would come from initiatives including a children’s party room, an improved retail area, fitness classes such as aqua-zumba, special events including night swimming and dedicated sessions catering for special needs groups.
But the biggest single change would be soft play. Mr Gailey said: “There is no soft play in Leith now since the one at Ocean Terminal closed. There is a demand for it and it’s a great way to cross-subsidise.”
Waterworld used to open three days a week, but Splashback say opening an extra day would incur only extra staff costs, since the venue is heated all the time anyway, and would allow special schools more opportunity to use the pool.
And there would be a campaign to market Waterworld across the city.
The voluntary board that would run the pool – made up of councillors, community representatives and partner groups – would also be set up as a charity, which would make it eligible for lottery cash and other funds which the council cannot access.
Mr Gailey said: “We are not saying we will run this for the council. We are saying we will run this with the council.
“Andrew Burns and Labour have talked about the co-operative council. This is the first big test of whether they are going to be different from before.”
He said the group had carried out an analysis of the social benefit of the pool, based on a model used by Edinburgh Leisure, and calculated that Waterworld produced a return to the public purse of around £242,000, through savings to the NHS and savings to employers from reduced absences from work.
Mr Gailey said: “This summer everyone has been watching the Olympics and now the Paralympics, and want to honour the athletes.
“The question is how we want to honour them – is it just a one-off bus parade or is it with a long-term investment, looking at how kids across the city can take part in and enjoy sport, with all the long-term benefit which comes from that?”
The future of Waterworld was due to be considered by the council’s policy and strategy committee, but council chiefs decided instead to take it straight to the next full council meeting on September 20.
Councillor Richard Lewis, the city’s culture and leisure leader, said: “Putting the bid to the council meeting instead of the policy and strategy committee means campaigners can put their case directly to all councillors.”
The council refused to say whether it had received any other bids for Waterworld.