A 91-year-old man suffered multiple hip fractures when he slipped on water from leaking refrigerator units at Tesco in Jarman Park.
Tesco Stores has pleaded guilty to breaching health and safety law, following an investigation by Dacorum Borough Council.
Luton Magistrates’ Court heard the case this week, which relates to an incident on Monday, August 6, 2015.
The court heard that the leaks had not been able to clear because of blocked drains under the floor, and that Tesco had not cleared away the pool which had resulted.
District Judge Leigh-Smith adjourned sentencing, and a further hearing will take place on May 23.
Cllr Neil Harden, portfolio holder for community and regulatory services, said: “We will always take action where we deem it necessary to protect the public.
"This conviction will send out an important message highlighting the need for businesses to comply with health and safety law and take all appropriate measures to prevent risk of injury to their employees and the public.
“Our officers are happy to offer guidance to businesses to ensure no such issues arise, I would advise businesses to make use of that free advice on the HSE website www.hse.gov.uk as we won’t hesitate to take action when we consider it necessary.
“The council’s environmental health team is employed to investigate serious accidents, ensure that businesses comply with health and safety law, and to take action where they find non-compliance.”