Public urination has become so bad in San Francisco that the city has painted nine walls with a repellent material which sprays offenders back.
Ultra-Ever Dry, a clear liquid repellent which goes on like paint, causes urine that hits the material to spray back on to a person’s shoes and trousers.
Mohammed Nuru, director of the city’s public works department, said he got the idea from Hamburg, Germany, where walls are painted with a clear material to discourage late-night drinkers from urinating in alleyways.
Mr Nuru, whose Twitter handle is @MrCleanSF, said: “If you have to go, go in the right place.”
The issue has been a long-standing problem in the city, where a light pole corroded by urine recently fell on a car, according to Associated Press news agency.
Mr Nuru added: “We are getting calls from all over the place: Washington, DC, Hawaii and Oakland.”
Signs hanging above some of the walls read: “Hold it! This wall is not a public restroom. Please respect San Francisco and seek relief in an appropriate place.”
San Francisco already has solar-powered rolling toilets in one neighbourhood and attendants manning public toilets to encourage people to use them.
Kevin Sporer, superintendent of the building repair bureau, said: “There’s a lot less activity, and the result is noticeable.”
Public urination is illegal, and carries a fine of up to $500.
The city spends $80 an hour to steam clean walls and sidewalks and has seen 375 requests for steam cleaning since January.