The Anti-Austerity Alliance is claiming the latest registration figures from Irish Water are a disaster for the company.
Irish Water has admitted that more than 500,000 households have yet to register with the utility.
It says 1.32 million households have registered their details, but it believes that is only around seven out of every 10 households.
Anti Austerity Alliance TD Ruth Coppinger claimed the company are trying to give the impression that there's been a rush of registrations, when in fact only 90 thousand households had signed up since March 19th.
It is encouraging the rest to get registered before next Tuesday - which is the government deadline to receive the €100 'water conservation grant'.
Head of communications with Irish Water, Elizabeth Arnett said: "All households across the country are entitled to the government €100 Water Conservation grant – even those who are part of a group water scheme or have a well and a septic tank and are therefore not customers of Irish Water."
"We are urging all households to register with us so that they will not miss out on this €100 government grant in September", she added.
The utility is still being criticised by opponents of water charges, for refusing to reveal how many customers have paid their first bills so far.
Anti-Austerity Alliance TD Paul Murphy lodged an appeal earlier this month, after the internal reviewer of Freedom of Information requests at Irish Water rejected his request for details on how many people have paid their bills.
