The 34-year-old from Walsall, who has asked not to be named, was clearing a blockage for Tardis Environmental UK Ltd at a partially completed housing development when the incident occurred on 26 August last year.

A pump at the bottom of the sewage well had stopped working because it had become blocked with “rag”, bulky waste material like nappies.

To remove the waste the employee used a road tanker with pump and hose attachments. He opened a grid at the top of the well and stood over it to support and manipulate the hose.

As he did the hose kicked back and hit him, causing him to lose balance and fall into the chamber.

He managed to grab the hose as he fell and slid down it into the waste at the bottom where he stood disorientated for around twenty minutes before he realised he had his mobile phone with him and was able to call for help.

He ingested raw sewage, sustained friction burns to his arms, and bruised his elbows, knees and head in the fall. He was off work for a number of days.

An investigation by the Health and Safety Executive (HSE) found the Tardis employee had been trained in the use of the pumping equipment but had not received any instruction or training in how to empty deep, below-ground sewage wells with specific regard to the risks involved with working at height.

Tardis Environmental UK Ltd, of Bloxwich pleaded guilty to breaching safety regulations at Dudley Magistrates’ Court and was fined £15,000 and ordered to pay £3,000 in costs.

After the hearing HSE inspector Anthony Woodward said:”The incident was entirely preventable.

“The nature of the work meant the worker was right next to, and leaning over, the deep well. Although he was working at ground level the depth of the pit meant he was working at height so reasonable precautions to prevent a fall should have been provided by the company, such as a worker’s restraint or harness.

“He was lucky to escape serious injury or further harm. If he had not have grabbed onto the hose to slow his fall, he might even have been killed. It was an extremely unpleasant experience that he should have been protected from.”