It's toilet harassment, outraged workers said.
A Chicago company pays staff US$1 (S$1.24) a day - for not going to the loo. Otherwise, they're allowed only 6 minutes a day to use the bathroom.
Workers staged a demonstration in front of the company headquarters earlier this month.
The union also filed a complaint against the employer WaterSaver Faucet Co. and its sister company Guardian Equipment Inc.
Members of the Teamsters Local 743 who build sink stations told The Chicago Tribune that workers have been disciplined for exceeding their allotted bathroom time of 30 minutes per week, or 6 minutes per workday.
"They offered $1 per day for anyone who doesn’t go to the bathroom at all," said Mr Nick Kreitman, senior business agent for Teamsters Local 743.
So far, 19 people have been disciplined, with written or oral warnings, he said.
The union contract currently allows for a 7.5-hour workday, including a 10-minute break in the morning, a 30-minute lunch break, a 15-minute afternoon break and a 5-minute cleanup period before the shift ends, according to Steven Kersten, owner and president of WaterSaver Faucet.
The company installed a bathroom tracking system, in which employees swipe their ID cards to get into the bathroom, earlier this year.
Company representatives say the discipline began only after workers ignored previous pleas to use bathroom times wisely.
Owner Kersten said there is no bathroom “allotment” beyond scheduled breaks and workers were only disciplined when the tracking system showed they were taking excessive bathroom breaks.
Going to the loo = lost productivity?
He cited one worker who was tracked using the bathroom six times in one shift, including two minutes before his scheduled morning break.
“Our point of view is that anyone can go to the washroom when they need to but what bothers us is extended periods of time and multiple trips that cause lost productivity,” Mr Kersten said.
Under the company's reward system, workers can earn a gift card of up to $20 each month ($1 a day) if they don't use the bathroom at all during work time, CNN.com reported.
The union, which represents 140 employees of the companies, is currently negotiating a new contract.
"It creates a lot of job stress," said Mr Kreitman. "The owner buys your time and [the owner] doesn’t buy your time with bathroom breaks."
Sources: CNN.com, The Chicago tribune