At least 1,000 people are dying each month from kidney problems in hospitals because of a lack of basic care.
That is according to a report by an NHS doctor who called the death toll "completely unacceptable".
Known as 'Acute Kidney Injury,' the problem comes from patients becoming dangerously dehydrated while they are already vulnerable.
More people are dying from preventable illness than at the height of the hospital bug panics around MRSA and Cdiff of recent years.
The total cost of treating AKI is £1bn every year - more than is spent on treating breast, lung and bowel cancer combined.
Report co-author Marion Kerr, a health economist at Insight Health Economics, said: "Every day, more than 30 people are dying needlessly. Compare that to MRSA which was killing about four people a day at its peak. Simple improvements in basic care could save the NHS £200m a year and, more importantly, save thousands of lives."
Report co-author and renal physician at Salford Royal NHS Foundation Trust Professor Donal O'Donoghue, said: "These deaths are avoidable.
"This is completely unacceptable and we can't allow it to continue. Good basic care would save these lives and save millions of pounds for the NHS.
"Doctors and nurses need to make elementary checks to prevent AKI. In general, people who are having surgery shouldn't be asked to go without water for longer than two hours.
"Sometimes that is unavoidable but then medical staff need to check their patients are not becoming dehydrated."
A spokesman for NHS England said: "We have taken steps to ensure the NHS puts in place coherent long-term plans to reduce avoidable deaths in our hospitals, and to improve the way data is used in decision making.
"Health research based on real life evidence like this is vitally important for NHS commissioners in choosing where to target their resources, and we thank Insight Health Economics and NHS Improving Quality for carrying it out."