People’s belief that polluted drinking water is the principal medium through which environmental toxins are absorbed into the bodies of CKD of unknown etiology (CKDu) patients in the CKDu-endemic areas in Sri Lanka has been the subject of extensive epidemiological and medical research. This study examines (a) the people’s perception and experience that polluted drinking water is the cause of CKDu, (b) how the government responded to people’s demands for potable water, and (c) the impact of the use of alternative drinking water sources on the health of CKDu patients and their families, and on the progression of the disease in CKDu patients. Data were collected in 2013 and 2019 in Anuradhapura and Polonnaruwa districts in North Central Province of Sri Lanka. People’s agitation, activism, and lobbying, together with the media’s work in bringing the issue of polluted water to the forefront of political discourse, have prompted the government, private sector agencies, and community organizations to supply clean water to affected communities. A massive change in drinking water behaviors has occurred following the government’s decision to supply reverse osmosis (RO) water to the affected communities. Informants perceived the provision of RO water as having brought about many positive outcomes in the health and disease progression of CKDu patients.