The Occupational Health and Safety Administration requires that buildings in the U.S. have one toilet seat for 20 workers. For facilities serving 20 or more people, OHSA requires one toilet seat and one urinal per 40 people. Any facility with more than 200 people must have one toilet seat and one urinal per 50 workers. Different rules apply to special events and construction sites.
For construction sites in the U.S., OHSA requires one portable restroom for the first one to 10 workers. If a site has 11 workers, it must have two portable toilets. Up to four toilets are required for sites with 31 to 40 workers. Sites with more than 40 workers must add one more portable restroom only for every increment of 10 workers.
Special events have flexible rules and recommendations about the number of toilets per person. Hall's Serv-All recommends increasing the number of toilets if a special event has a higher number of women than men or if alcohol is available. A three-hour event for 200 people has a baseline requirement of three portable bathrooms, though having six to eight portable bathrooms is preferred.
According to the Americans With Disabilities Act, 5 percent of toilets at office buildings, restaurants, special events, schools and public buildings must be handicap-accessible. This rule does not apply to construction sites.