So-called 'code brown' incidents at Auckland swimming pools hit a record during summer, prompting Auckland Council to push out an educational campaign on this public health issue.
One pool worker told Seven Sharp there are upwards of about 25 incidents a month of pool users defecating in the water.
"Across the region there's about one hundred across the summer," said Alex, who's in charge of dealing with 'code browns' at West Wave Pool and Leisure Centre.
This summer he has seen three code browns in one day.
"Main culprit is the little kids, the under-threes, the ones that haven't been toilet trained," he said.
Alex said a swim nappy on a youngster can avoid the problem "100 per cent."
"The swim nappy is really good at just containing those little accidents."
The protocol is that pool is closed immediately after such an incident, the excrement is scooped from the pool and flushed down a toilet and the dirty pool water is then removed.
"We basically reverse the way the water flows through the filter, push it all back out, take some of that dirty water out from the incident and put it into the sewers to get rid of it," Alex explained in the pool's pump room.
"We have got to re-sterilise it and make it a lot cleaner than it normally would be."
He demonstrated pouring chlorine from a jug into the pool "to super-clorinate it".
It can take up to 24 hours before testing gives a pool the all clear to open again.