E. coli | Turbidity
Microbiological contamination of water has long been a concern of the public. Many infectious microorganisms found in the environment – including shigella, escherichia coli, salmonella, s. aureus, yeast and mould – can cause symptoms such as nausea, vomiting, diarrhoea and stomach cramps. While conducting this test, E. coli was spiked in the input challenge water at regular intervals of 300, 600, 900 and 1,200 litres of various concentrations. Spiking level was kept higher to check efficacy of the product in worst/adverse conditions. The output water was tested to check the efficacy of the filter.
This refers to the amount of dissolved solid particles that are suspected to be in water and that cause light rays shining through the water to scatter. Thus, turbidity makes the water cloudy or even opaque in extreme cases. The turbidity of drinking water should not be more than 3 NTU and ideally be below 1 NTU. This is a key quality indicator for a water filter/purifier and the test was conducted as per the requirements of IS: 7402. All the brands of water purifiers were able to remove turbidity to a level that makes it safe and suitable for drinking.