In dairy farming a milk cooling tank is a large storage tank for cooling and holding milk at a cold temperature until it can be picked up by a milk hauler. The bulk milk cooling tank is an important piece of dairy farm equipment. It is usually made of stainless steel and used every day to store the raw milk on the farm in good condition. It must be cleaned after each milk collection. The milk cooling tank can be the property of the farmer or be rented from a dairy plant.

Rapid and efficient milk cooling is essential for preserving milk quality. Milk leaves the udder at approximately 35°C and the heat in fresh milk must be quickly removed. Milk retains a natural resistance to bacteria immediately after extraction, but only rapid cooling to a storage temperature of around 4°C to 6°C, prevents or minimizes further micro-organism growth.