UP to 100,000 homeowners in Ireland have put 2 fingers up at new laws aimed at protecting drinking water sources.

The Department of the Environment expects just 400,000 people to have registered their septic tanks – despite the threat of fines of up to €5,000.

Almost 500,000 households had a deadline of February 1st 2013 to register, but one in five have refused to do so.

The latest figures yesterday showed just 360,000 have registered online, with another 10,000 sent by post which have yet to be processed.

"We are confident of reaching 400,000, or 80pc of the total, by the weekend," a spokesman for the Department of the Environment said. "Registrations are continuing to flow in."

Only householders who have registered their system by yesterday's deadline will be eligible for financial support if their tank fails an inspection.

Up to 80% of the cost of repair works, up to a maximum of €4,000 for those earning up to €50,000, will be funded by the department.

A 50% grant for those earning up to €75,000 is also available, to a maximum of €2,500.

The inspection regime comes after the European Court of Justice ruled that Ireland had failed to protect drinking water sources. In December, it fined the State €2m for failing to introduce an inspection regime, along with daily fines of €12,000.

The Government hopes that the rollout of an inspection regime, which will begin shortly, will persuade the European Commission to drop the case against the State.

Experts believe up to 125,000 tanks may pose a threat to groundwater sources because they are poorly designed, located or not properly maintained.

Householders will be given 10 days' notice that an inspection will take place, and will have 21 days to rectify any problems.

Failure to comply with an order to make improvements can result in fines of up to €5,000.

The registration is opposed by the Campaign Against Household and Water Taxes, which has urged people not to pay. It claims the grants being provided will not cover the costs of the necessary improvements.

It is an offence not to register a tank. It costs €50 and can be done online at www.protectourwater.ie, by post or through local authority offices.

Comment by Sapphire:

Having operated in Ireland, we think that the majority of septic tank systems will fail the inspections. Ireland is too wet for soakaways to work and unless the EPA changes the rules to allow sewage treatment plant effluent to discharge directly to a ditch, as it does in the UK, we cannot see way forward for many Irish householders.

Be warned, our septic tank legislation is yet to come in the UK.