Retailers are increasing milk prices due to a shortage of supply from dairy farmers, but it still remains cheaper than a bottle of water.
Retail giant Morrisons has increased its price of a four-pint bottle from £1 to £1.10 due to soaring coasts at farm gate.
Industry experts believe that the fall in milk production will set off a "milk price war" with other supermarkets.
A Morrisons spokesperson said the supermarket tried to hold prices down but "needed to respond when there were ongoing cost pressures". More supermarkets are likely to follow.
Its decision to up prices follows a sustained period of restricted supply from dairies that has also sent the price of butter higher.
Supply has been tightened because many dairies have shut down following a price war started by the supermarkets back in 2014.
However, NFU dairy board chairman Michael Oakes has welcomed the price increases, saying it "reflects the true cost of milk production".
In October, the price of four pints of milk rose by 4p in October to 99p - the highest level since January 2015.
