Workers from the country's largest supplier of drinking water to the corporate sector, Just Water, are on strike, after a breakdown over negotiations for better work conditions.
They stopped work at 4:30am and will continue until 11pm tonight.
FIRST Union spokesperson, Jared Abbott, says workers are on low wages and often have to complete long work shifts which are physically taxing.
He says they often work 12-hour days, carrying 15kg bottles up and down stairs.
Abbott says workers want the company to come to the negotiating table, listen to them and recognise that they often work overtime for little pay.
Just Water chief executive Tony Falkenstein said the company was a "finalist in the IBM Best Workplaces Awards for 2017, pays above award rates, offers monthly incentives, free bbq breakfasts, free flu shots and a number of other perks".
Falkenstein said he and other members of management would be out delivering water today and that the union would not even advise which members of staff belonged to it.
Eight of the company's 120 workers were union members and involved in the strike.