According to the data provided by Fluence, 1,890,000 litres of water are needed to raise one cow, 103,950 litres (5.5%) out of 1,890,000 are considered to be for leather*. According to their calculations, about 6kg of leather are produced per head, in other words, each kilo of leather requires approximately 17,000 litres of water. This amount is confirmed by the Water Footprint Network.
*fluencecorp.com/water-use-in-the-leather-industry