Nearly one in five building sites have no drinking water or separate gender bathrooms, a survey of 3,500 Unite members has found.
The survey of construction workers, seen exclusively by Construction News, found that many sites failed to meet the legal requirements for workplace welfare facilities.
Regulations state employers are required to provide of drinking water as well as “adequate” toilet, washing and kitchen facilities.
The research suggested that more than one in six sites (17 per cent) forced men and women to share toilets, with no separate facilities provided for women. The same proportion had no drinking water available.
Individual responses to the survey told of sites where 30 toilets were provided for 2,500 members of staff, while in another instance facilities were located a 10-15-minute walk away.
In total 18 per cent of respondents said they believed workplace toilet facilities were “not adequate”, with 10 per cent of sites failing to provide toilet paper.
The survey also found problems with cleanliness in relation to some kitchen and washing facilities.
Sixteen per cent of respondents claimed their sites had no separate showers for women, 3 per cent said showers and toilets were never cleaned, while in 8 per cent of cases they were only cleaned weekly.
Cleanliness was also an issue when it came to canteen or mess facilities: 4 per cent of respondents said these were never cleaned, while in 6 per cent of cases these facilities were only cleaned on a weekly basis.
Unite assistant general secretary Gail Cartmail said: “Providing toilets and washing facilities is not a luxury; they are a basic human right.
“This survey must act as a wake-up call to the construction industry. In the 21st century there is no excuse for any workplace not to provide clean and decent welfare facilities.
“Companies that fail to provide decent welfare facilities can and should be prosecuted, and this is an area where Unite is working with the Health and Safety Executive to ensure standards are improved.
“Where Unite is organised on a site we will always ensure that decent welfare facilities are provided and will ensure our members take the necessary measures to ensure they are in place.”
The Health and Safety Executive has been contacted for comment.