The worker, understood to be in his 40s, fell through the hole to the bottom of a storm drain while working on a storm water holding tank at the Lyme Green Business Park in Macclesfield. He was pronounced dead at the scene.
A Morgan Est spokeswoman said: “We can confirm that a fatal accident involving an employee of one of our sub-contractors occurred at a construction site in London Road, Macclesfield, where we are undertaking clean water and waste water works for United Utilities.
“Our safety team is working with the Health and Safety Executive to establish how the accident occurred.”
She added: “Safety is paramount at Morgan Est and we are greatly shocked and saddened that such a tragedy should have happened.
“Our thoughts are with those personally affected. Until we have the results of the investigation, we cannot comment any further.”
The Health and Safety Executive and the police are investigating.