Despite the now two-year-old facility doubling the number of lessons per week, there is still a waiting list of between three and six months.
Liberal Democrat councillor Bob Smytherman believes this shows the Aquarena replacement needed to be larger.
He said: “I think it shows the council’s decision to build a smaller pool on a smaller site was short-sighted and I believe the council missed a huge opportunity to build a 50 metre pool on the whole Aquarena site.”
The issue became apparent at a meeting of Worthing Borough Council’s planning committee on Wednesday,.
Councillors were discussing a retrospective planning application for a private pool in Seaview Road, used by owner Morwenna Wells for swimming classes.
Speaking in support, parent Katharine Archer said: “Splash point could not accept any more lessons. There is no other viable option for my seven-year-old to be able to swim.”
Splashpoint, which opened in 2013, was designed with moveable floors to enable more lessons to be timetabled each week.
Former council leader Paul Yallop told the committee this was a move to enable more children to be able to learn to swim – something he felt was vital in a coastal town.
Speaking after the meeting, South Downs Leisure chief executive Duncan Anderson said the Aquarena waiting list was between three months and a year, with many customers heading to Littlehampton as the old pool was too deep.
He said: “Since we have moved to Splashpoint, as a result of the moveable floor we have steadily grown the swimming lessons to the current usage of 1850 per week, which is more than double that of the Aquarena.
“The waiting list is anything from three to six months and we are about 95 per cent full.
“This is a great success and we are always looking at ways to open more spaces to customers but sometimes this comes at the detriment to lane swimmers or general public sessions.”
The Seaview Road pool was granted planning permission, with a low amount of usage deemed unlikely to cause disruption to neighbours, in the committee’s view.
The facility is often used by children with additional needs who struggle to learn in the usual environment.