The Orange Aquatic Centre is expected to re-open on Saturday after being closed since Thursday to allow a super-chlorination on all three pools.
It follows the pool being informed that a person who attended the pool had been diagnosed with cryptosporidiosis.
It is an illness with gastro-like symptoms caused by cryptosporidium, a single-cell parasite bacteria.
Orange City Council spokesman Nick Redmond said there was no confirmation that the pool was the source of the infection.
“A diagnosis from a doctor confirmed that the person had contracted cryptosporidiosis,” he said.
“The diagnosis can’t show where the person received the infection.
“Under Health Dept protocols, doctors are required to notify health authorities of an infection such as this. In this case, the Aquatic Centre learnt directly from the person concerned.
“This is the first incident of a cryptosporidium infection that has impacted the pool for some three or four years.”
Mr Redmond said the pool took the precaution to conduct the super chlorination.
This is on top of the regular UV treatment, which treats all of the water more than six times every day.
“The water in the toddlers pool is treated with UV every one and a half hours, the 25-metre pool every two and a half hours, the 50-metre pool every 3.8 hours),” he said.
“The super chlorination process involves raising the amount of chlorine in the water in the pools to a much higher than normal level and keeping it there for 26 hours.
“The next step is flushing these high levels of chlorine to let it come back to a level which is comfortable for swimming.”