It's the latest in a string of woes for Wellington Water, which is now notorious for burst pipes and leaks – as well as the fluoride scandal, discovered last month.
A damning report revealed water in the region hasn't been fluoridated properly for six years.
A review was launched after the revelation that Wellington Water turned off fluoride at two plants last year without telling the board, councils or residents.
It found fluoride was administered effectively less than 20 per cent of the time at those plants, which supply Upper Hutt, Porirua and Wellington City residents.
Wellington Water is working towards reinstating fluoridation by September this year.
The board will implement all of the review's recommendations, including that Wellington Water should have a relentless focus on fluoridation.