The national water industry body says rules on water quality are not set in concrete and will develop further.
New national fresh water standards which, for the first time, set minimum quality requirements for rivers, lakes and aquifers were announced earlier in the year.
Water New Zealand is holding its annual conference in Hamilton from today. Chief executive Murray Gibb said the rules are a work in progress and would be reviewed in 2016.
"There's been debate as to whether or not it's sufficiently tight and there's been a lot of debate over whether or not the corner-stone policy that it imposes a requirement on councils to maintain and improve overall water quality within their regions might lead to declining water quality in some water bodies.
"Of course for that to occur, the people who live adjacent to a lake or a river would have to agree to that and I very much doubt there would be many New Zealanders that would stick their hands up and say to their regional councils, 'Look we're quite happy for our water quality in our river or our lake that we want to swim in to decline'. I think that's simply unrealistic".
Mr Gibb said the conference today would look at water reforms in Australia and water management in New Zealand.