Mrs Pham has successfully lobbied Shoalhaven City Council to install a fully accessible toilet inside the Nowra Aquatic Centre as part of its multimillion-dollar redevelopment.

It will be the first accredited "Changing Places" toilet in NSW and will cater to the needs of disabled adults and older children who require specialist equipment including an adult-size change table and ceiling hoist.

For Vincentia mother Mrs Pham it will provide "dignity" for her 12-year-old son Liam who has cerebral palsy and other chromosomal abnormalities, leaving him severely intellectually and physically disabled.

She started a petition on change.org last September to try to get the Building Code of Australia changed to make disabled toilet blocks more accessible for the severely disabled - it has since garnered 41,000 signatures.

"Disabled toilets cater for people with mild disabilities and mobility problems, not for children or adults with profound disabilities who require help changing," Mrs Pham said.

"Parents and carers like myself - who can no longer use baby change tables - have no option but to leave our older children or adults in soiled nappies or change them on the dirty floor of a disabled toilet or even a park bench."

Mrs Pham has taken her campaign to local and state politicians, and there have been moves to install the facilities at Sydney's Parliament House. She has had some support from organisations like Stockland too, but the Nowra facility will be the first to become a reality.

"It means a lot that Liam or anybody like him can go to the swimming pool and have access to suitable changing facilities," she said.

"Liam doesn't have the cognitive ability to understand what's happening, but when it's complete he'll certainly know he's not on the floor of a disabled toilet, that he's not sitting in a wet nappy for hours - he'll be a lot more comfortable."

The Changing Places project began in 2006 in the UK, which now has about 700 such facilities.

Shoalhaven Mayor Joanna Gash said the facility, which would cost about $20,000, would be part of the Nowra centre expected to be finished by June.

"There are many older children or adults who are too heavy for a baby change table and changing them on the floor or a park bench is simply not good enough."