A Canberra pool voluntarily closed to the public last year after tests revealed high chlorine content.
A government inspection at the Tuggeranong Lakeside Leisure Centre discovered combined chlorine levels double the advised rate.
A follow-up visit recorded improved, but still high, levels and the pool was voluntarily closed temporarily.
Despite the incident, the ACT's public swimming pools recorded a high standard of hygiene in 2011.
Health officials carried out 21 inspections at ACT pools last year.
There were four minor instances of non-compliance, with all cleared soon after discovery.
An ACT Health spokesman said inspectors test water chemistry, such as pH and chlorine levels, and general hygiene during visits.
He said two of the incidents resulted from complaints, while the remainder were due to water chemistry.
Phillip pool was required to add more chlorine to the water and order a new flushing unit for the men's urinals.
Lakeside also had a bathroom hygiene complaint that was found to be unjustified.
The spokesman said the incidents detected were minor.
''The data represents a similar compliance rate when compared to 2010,'' the spokesman said.
''[Health] conducts inspections of a range of public health related activities, public swimming pools are one such activity.
''The community should be reassured that there is a public health regulatory function that undertakes these tasks.''