A hospital trust in charge of the care of an 85-year-old woman who died after drinking floor cleaner left in a water jug by her bedside has been rebuked by an inquest jury for the “widespread confusion” that ultimately led to her death.

Joan Blaber, from Lewes in East Sussex, was admitted to Royal Sussex County hospital in Brighton on 22 August following a minor stroke but her condition worsened after drinking the fluid on 17 September. She died six days later.

The inquest heard Blaber’s clear water jug had been removed during the afternoon and replaced with a solid green jug.

Alba Duran, a staff nurse, said she poured liquid from a jug into a beaker so Blaber could take her medication at about 10pm. Within minutes, she started coughing and vomiting after swallowing the liquid. Blaber was “frothing at the mouth” and “fighting for her breath” the next morning, the inquest heard.

On Wednesday, a jury at Brighton and Hove coroner’s court concluded: “Evidence leads us to believe there was widespread confusion surrounding the water jug system that was in place and that jugs were being misused. Understanding and implementation of cleaning procedures were inconsistent and inadequate among agency and trust cleaning staff.

“Furthermore, we find that management failed to direct and monitor staff, adhere to and enforce the control of substances hazardous to health regulations (COSHH), leading to ongoing breaches of regulation.”

The jury criticised the hospital trust for failing to learn lessons from a similar incident 14 months earlier, described at the inquest as a “near miss”.

The senior coroner, Veronica Hamilton-Deeley, said: “The jury have recorded serious failings, they have identified and explored them and found them directly related to Joan’s death, and in the light of this I shall be making a regulation 28 report.”

She said the report would require a response within 56 days and be sent to the hospital trust, department heads, the Care Quality Commission and other appropriate parties.

“In my opinion, this inquest has shown that action should be taken to prevent the occurrence or continuation of the failings the jury has identified, and thus eliminate or reduce the risk of deaths created by these failings,” Hamilton-Deeley said.

Nicola Ranger, the chief nurse at Brighton and Sussex University hospitals NHS trust, apologised to Blaber’s family.

“Since Mrs Blaber’s death, the trust has worked hard to put processes in place to prevent a similar incident happening in future. We have worked with our regulators, the police and partners, including Healthwatch, to ensure our response has been robust,” she said.

“This has included providing staff training, assessing our use of all our cleaning products and standardising the way we store and use potentially hazardous chemicals.

“Our staff work incredibly hard and demonstrate outstanding care and compassion for our patients every day. We are sorry, we have learned and we will continue to make every effort to improve.”

In a statement, Blaber’s family said they “do not blame Alba Duran personally for Joan’s tragic death”.

A police investigation in which 100 people were interviewed found no evidence the incident was malicious, the inquest heard.