TDs will vote later this week on Opposition legislation to hold a referendum on the ownership of water.
The Bill will be debated in the Dáil on Wednesday and a vote will take place on Thursday.
Thirty-nine TDs signed the bill last May, - including Sinn Féin, the AAA/PBP and Independents - as well as the Right2Water campaign and affiliated trade unions.
Independents 4 Change TD, Joan Collins says this places particular focus on the position of Fianna Fáil, whose votes could secure the bill's passage, and the Independent Alliance - which could be crucial if Fianna Fáil were to abstain.
She has called for these groups to "reflect widespread public feeling" as well as "their own public statements" by voting for the bill on Wednesday.