According to the company, a seconds-long delay in the maintenance work at one of its factories in Shanghai caused the alkaline cleaning solution to flush into nearly 300 cartons of milk, which were produced on 25 June.
Bright Dairy has said that it would provide door-to-door apologies to customers who purchased the contaminated milk and carry out a strict factory inspection.
The case is being investigated by the Shanghai Bureau of Quality and Technical Supervision.
This is the latest scandal to hit the Chinese dairy industry - just few weeks ago, Mongolia Yili Industrial Group recalled six months' worth of infant formula from shelves due to mercury contamination.
China's dairy industry has been plagued by a series of scandals after the tainted milk controversy in 2008, in which 22 dairy companies were implicated for using the industrial chemical melamine in milk and infant formula.
The country has been struggling to control food safety violations despite harsher punishments and new regulations to address the problem.
