Modi had said earlier that he would take action to clean up the Ganga at Varanasi and make its water pure, as his government had done in Sabarmati's case.
"The water samples taken (by AAP's volunteers) from three different places suggest the voluminous presence of hazardous chemicals in the Sabarmati river," AAP's state convener Sukhdev Patel said.
Water was tested in private laboratories and the results showed that Sabarmati was the fourth most polluted river in the country, he said.
According to AAP, COD was 826 and 1950 respectively for two samples against the permissible limit of 30 while BOD was 325 against the permissible limit of 250. Total Dissolved Solid level was 13,500 against the permissible 2,000.
Industrial effluents were being released into the river, AAP alleged. "The pollution in Sabarmati may cause the diseases of digestive system and even serious diseases like cancer," Patel Said.
Patel said that AAP would raise this issue in Varanasi itself, where its leader Arvind Kejriwal is contesting against Modi.