Almost one-third of rental accommodation inspected by local authorities each year is failing to meet minimum standards.
New figures show that much of the sub-standard accommodation includes a lack of hot or cold running water, mould growing on walls or ceilings, vermin infestation and tenants living in windowless rooms.
Official figures obtained by housing charity Threshold show that 30 per cent of the 6,800 properties inspected fell below minimum standards. Yet legal action was initiated in just 11 cases.
At the launch of its annual report yesterday, Threshold chairwoman Aideen Hayden said minimum standards were "primitive and outdated".
Existing standards do not oblige landlords to provide a cooker or central heating.
"The current system of inspection is hopelessly inadequate.
"People are entitled to live in safe, secure accommodation. We need a system that makes sure all rented property is fit to live in, both in relation to minimum standards and fire safety.
"It is ironic that the home, which is the place where safety matters most, is almost the last area for appropriate regulation."
Threshold is calling for a system of certification to ensure all rented property meets a decent standard. Under an "NCT for housing", qualified professionals would certify properties for minimum quality standards and fire safety.
Threshold also claimed some local authorities were not carrying out any inspections of rented properties. While Dublin City Council carried out over half of all inspections nationally (3,735), 19 local authorities failed to inspect any properties last year.
These include Cork County Council, Galway County Council, Limerick City Council and Limerick County Council.
Ms Hayden said local authorities that failed to inspect rented properties should have State funding for inspections - totalling €1.6 million - taken away. She called on Minister for Housing Noel Ahern to seek the return or reallocation of this money.
"The poorest people need protection because sometimes sub-standard accommodation is all they can afford.
"Many local authorities in Ireland are letting these vulnerable people down by failing to ensure their home is fit to be lived in."
Mr Ahern is reviewing regulations and said earlier this week that new standards would involve more regular and thorough inspections.
Under the new system inspectors would be asked to notify the community welfare service where they found seriously sub-standard accommodation.