Testing hospital water supply. Sample of hospital water being tested in a sensor for levels of chlorine and chlorite, and the disinfectant chemical chlorine dioxide (ClO2). This test is being carried out using the ChlordioX Plus sensor from Palintest, a company that produce a range of test kits used to monitor water quality and carry out analysis in applications ranging from environmental monitoring to industrial processes and public health. Photographed in the UK in 2016.