At the next Full Council meeting the Lib Dem group will call for Labour’s plans to fluoridate Hull’s water supply to be binned.
In recent weeks Labour councillors announced that they will push ahead with their fluoridation plans.
If successful, the proposal would affect the water supply across Hull and in the East Riding.
Labour councillors have yet to outline how they would pay the project which is forecast to cost £300,000 to set up and £100,000 every year after.
Currently the Council has a £10million overspend in its finances.
Lib Dem Councillor Linda Tock said: “Labour's plans to fluoridate Hull's drinking water are wrong. We think any funds available would be better spent on helping educate children in good dental health.
"When these proposals have been brought up in the past it was clear that many people in Hull didn't like the idea. I suspect the proposals will not be any more popular in the East Riding. There is a better way to tackle dental health and it is time Labour listened to reason.”