Scores of people fell ill with a sickness bug after the party at Splashes in Rainham, a report said.
Medway Council said it had had to lower the amount of chlorine in the water for the dye to work, but within guidelines.
Public Health England (PHE) said in a report the bug was likely to be linked to the lower chlorine levels.
It said chlorine checks that day at the pool had failed.
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A PHE spokeswoman said: "Our investigation revealed failures in pool maintenance procedures on the day of the outbreak, in relation to monitoring and recording of chlorine levels."
Medway councillor Howard Doe said: "We have worked closely with Public Health England to look into how customers could have become ill after visiting Splashes. I would like to say again on behalf of the council that we are sorry to those who felt unwell after enjoying the pool party."
The council said it would no longer use dye in its pools, as a precaution.
The report said it was not possible to say how many people became ill, but 93 people responded to a questionnaire and 68 people met the outbreak definition.
It said the outbreak had a "moderately high attack rate".
Investigators said it was not possible to work out how or where the norovirus was introduced or spread.
But they said people who put their head in or swallowed the water were at higher risk and the outbreak ended "abruptly" after the chlorine returned to normal which suggested it was "linked to reduced chlorine levels" on 28 October.
Recommendations included that the council should take remedial actions, review risk assessments over dye use, consider additional training and look at improving customers' "low compliance" over showering before and after swimming.
A council says it will no longer use dye in its swimming pools after turning the water "blood red" for a Halloween party led to a norovirus outbreak.