Threshold, the national housing organisation, is calling for radical reform of legislation governing the minimum acceptable standard of accommodation in the private rented sector.
The housing charity's annual report for 2004 shows a 36% increase in the number of requests for help from people living in unfit accommodation.
Last year local authorities inspected just over 7,000 rented properties of which almost 30% were found to be damp, vermin infested and had no hot water.
'The introduction of the new Residential Tenancies Act last year has greatly improved tenants’ rights in the private rented sector. But the Government must now copper-fasten this progress by tackling the quality of accommodation,' said Aideen Hayden, Chair of Threshold.
'It is totally unacceptable that people are forced to live in windowless flats, sleep in bedrooms covered in mildew or make do without hot running water,' she added.