Aquatic centre operations director Mark Meyer said the incident had been well managed by the Country Fire Authority.

“We were open as usual on Monday morning,” he said.

Mr Meyer said emergency services were called at just after noon on Sunday when a regular check uncovered a chemical leak.

“We had a small chlorine leak in our dosing pump,” he said.

“There was some chlorine that got into the hypo bund, which is designed to contain leaks.”

“It was a machinery breakdown that was unavoidable.”

The indoor pools remained open while Horsham police established a perimeter to stop people walking in to the outdoor pool area from O'Callaghans Parade.

About a dozen Country Fire Authority volunteers attended the incident on Sunday, which required the use of full protective equipment.

The authority listed the incident as safe at about 4:30pm the same day.

Mr Meyer said the leak was not an ongoing issue.