Over 60 per cent of septic tank owners have registered for the Government charge with two weeks left until the deadline, Minister for the Environment Phil Hogan said today.
"Only those who have registered their systems by 1st February will be eligible for financial support if their system fails an inspection," Mr Hogan said.
Donegal residents have the second lowest registration level with just 32 per cent (10,400) of tanks and waste water treatment systems registered.
Kerry residents have the highest compliance rate (at 86 per cent or 24,000), followed by residents of Clare (73 per cent) and Roscommon (67 per cent).
The Dublin City Council area has the lowest levels of registration (3 per cent). However, the council has said people may have mistakenly stated in the census that they had a tank. The city is served by an extensive piped drainage network.
Mr Hogan said he was conscious of householders' concerns over repairing their systems if they fail inspections.
"I want to reassure people again that they will be assisted in meeting those costs if remedial works are necessary," he said.
Last month, he announced a grant scheme of up to 80 per cent of repair costs for those earning up to €50,000, up to a maximum of €4,000, and a 50 per cent grant for those earning up to €75,000, up to a maximum of €2,500.
The Local Government Management Agency has reported an increase in online registrations in recent days. Over 1,000 people have reportedly registered online in the past 24 hours.
Registration for the €50 fee can be done online at ProtectOurWater.ie, by post or through local authority offices.