The gender split last year was broadly similar to previous years: 78 per cent of fatalities were male, 22 per cent female.
Beaches were the leading environment in which people drowned in 2018, being the site of 18 deaths, followed by rivers (13), and home pools (eight) and inland still waters (eight).
"Preventable fatalities include recreational and non-recreational drowning deaths," Water Safety NZ said.
"They do not include those fatalities classified as 'other' - arising as a result of road or air vehicle accidents, homicide, suicide or of unknown origin - as these are not considered applicable to the prevention and rescue efforts of the water safety sector."
Water Safety said there were four preventable drownings during the holiday period, which ran from 4pm on December 24 to 6am on January 3.
However, Herald reports indicate there have been nine water-related deaths since December 21. Some may not fit the definition of preventable, and causes of death - whether or not they were drownings - are for coroners to determine.
Water Safety said the number of preventable drownings during the holiday period were half the toll for the same period a year ago.
Mills said that while that was encouraging, "one preventable drowning is too many and a tragedy for all families and communities involved".
"This has been another holiday period of record rescues and call outs for our frontline services which indicates the toll could have easily been much worse" said Mills.
"We are fortunate to have such dedicated volunteers keeping Kiwis and visitors safe in, on and around the water.
"While our waterways are our playground they can be unforgiving and need to be treated with appropriate respect.
"The summer holidays go on for a couple more months yet and we know Kiwis will continue to enjoy our beautiful waterways as the warm weather continues. We need all Kiwis to take responsibility and think about water safety.
"Remember the water safety code. Be prepared, watch out for yourself and each other, be aware of the dangers and know your limits."
The average toll during the defined holiday period for the last five years is eight preventable drowning fatalities.
Water-related deaths since December 21
• Myung Kang, 57, has been missing since going fishing at Bethells Beach on Saturday
• Leka Pasiaka, 16, was swept out to sea while swimming at Whatipu on December 29. A body believed to be his was found on Tuesday.
• Grace Marie Griffin, 13 months, drowned in a ditch at Ashburton on January 6.
• Bruce Ngapera, 65, went missing after going fishing in a boat north of the Hokianga Harbour on Monday. His body was found later that day.
• The body of a man who had drowned in Lake Taupō was found on December 26.
• A diver died in the water at the Bay of Islands on January 4.
• Aman Kumar, 20, died in the Maraetotara Falls near Havelock North on December 21.
• Gary Hibbs, 58, was pulled from the water unconscious at Seatoun in Wellington on December 24. He had been diving. Attempts to resuscitate him were unsuccessful.
• A woman who had gone for a swim was found dead on December 28 at the Mangawhai estuary.