Contaminants in the city's water supply are a major cause of several infectious diseases, including cholera, typhoid, hepatitis, polio, cryptosporidiosis, ascariasis, and schistosomiasis, Daily Times learnt from health experts on Sunday. Corroded pipelines: The experts said that human excreta had polluted the water supply in the city during the recent rains. "Corroded pipelines add to the misery of the citizens, mixing sewage and causing water-borne diseases,' they added. Pakistan Medical Society President Dr Masood Sheikh claimed that 20 percent of the patients admitted to private and government healthcare centres daily had enteric diseases. He said, "During heavy rains people get infections, as the human waste can enter the drinking water when the pipelines overflow. The government should educate the citizens about maintaining a clean and healthy environment to reduce this.' Punjab University College of Earth and Environmental Sciences Professor Nawaz Chaudhry lamented that no study had yet been carried out across the country that had clearly shown the proportion of human waste in drinking water can result in infections. He said, "Human faeces can cause more diseases as compared to animal waste.' Anthropologist Shakir Khan said, "Human waste in the urban areas pollutes the environment the worst.'