West Douglas MHK Chris Thomas wants the £50 sewerage charge to be delayed by one year.
He believes there are many questions about how it is administered, and its fairness, which need to be answered before it can be approved.
Mr Thomas quizzed Water and Sewerage Authority Chairman John Houghton in the House of Keys yesterday.
He believes the whole thing is being rushed through Tynwald this month to help Treasury Minister Eddie Teare present his budget: (play audio)
Mr Houghton says he wouldn't have proposed the earlier introduction of the charge if he had had a choice.
And he believes Tynwald will vote in favour of the proposal later this month, despite widespread public opposition to it.
Clip 1
ICO proposes revised data protection fee model after consultation
'We can persevere in the face of uncertainty'
Incapacity benefit claims remain stable as annual cost rises to over £15 million
DoI 'carried out inadequate searches' in response to FoI
Bowel cancer awareness campaign returns with Island-wide initiative