The Cook Islands Opposition claims there is no doubt the bill setting up an authority to run Rarotonga's new water system will have to be overhauled.
Public consultations have been held and the three opposition MPs on the select committee, Terepai Maoate, Sel Napa and Agnes Armstrong, said there was a demand for critical changes.
Maoate said people questioned areas of the To Tatou Vai bill and asked that it be changed to be more beneficial and fairer to the public.
This included plans for a user pay system which Maoate said didn't reflect the original kaupapa or agreement the landowners had with government.
The Opposition MPs said the involvement of so many raising questions over the bill, and marching against it, showed the people would act if they didn't think a proposed law was in their best interests.
The Opposition said people also questioned whether the cost of running To Tatou Vai Authority could be justified, saying it would have far too much control over Rarotonga's water resource.
Attempts to reach the minister driving the scheme, Mark Brown, for comment, have so far been unsuccessful.