Pakistan is the world's fourth largest producer of milk. Domestic demand is strong and some 90 percent of the population consumes untreated raw milk. This provides an opportunity for corrupt retailers but also for farmers who are trying to survive inflation and falling profits. Some use illegal methods to increase the volume of the precious liquid – diluting milk with tap water is one of the most widespread techniques. Others even create fake milk from chemicals. Faced with this serious threat to public health, the authorities in Punjab province have stepped into action, as our correspondents report.