Firms are said to be putting lives at risk by illegally tapping into fire hydrants.
Yorkshire Water said the crime reached an all-time high in July, when millions of litres of water were thought to have been illegally siphoned from hydrants.
Of the 78 thefts reported so far this year, 32 were in West Yorkshire, 23 in South Yorkshire, 13 in North Yorkshire and 10 in East Yorkshire.
Fire crews say the crime could make it hard for them to deal with emergencies.
Ian Bitcon, from West Yorkshire Fire and Rescue Service, said: "Our front-line appliances carry adequate water to deal with the early stages of fire, and to extinguish most fires, but we rely on hydrants to support our work.
"Anyone interfering with or vandalising a hydrant is putting lives directly at risk."
Water is being taken from fire hydrants and "wash out" hydrants, which can be legally accessed with standpipes by workers such as window cleaners, road sweepers and drain jetters.
Yorkshire Water said it believed unusually dry conditions over the past few months, coupled with the challenging financial conditions faced by many businesses, had led to an increase in the crime.
It said illegal standpipes were too large for most hydrants and caused an increase in pressure which could stir up sediment in the water pipes and lead to water discolouration.
Melanie Dawson, from Yorkshire Water, said: "We want [the thieves] to know their actions can have extremely serious consequences.
"Not only do they risk damaging fire hydrants, and consequently endangering human lives, but their actions can also lead to water discolouration or even temporary loss of supply, which at its worse can affect thousands of people."
Five businesses have been prosecuted in the past eight months after they were found illegally tapping into hydrants. The maximum fine for each offence is £1,000.