Chemical analysis of drinking water to compare reverse osmosis processed and unprocessed water quality

Context: Reverse osmosis (RO) is a water purification technology that uses semi-permeable membrane to remove ions, molecules, and larger particles from drinking water. However, it is to be remembered that water contains range of minerals, necessary for the human body. Low mineral content has been observed to cause various health hazards such as dental caries, hypertension, and coronary artery disease. Aims: The aim of this study is to perform the chemical analysis of drinking water processed by RO in terms of total dissolved solids (TDS), hardness and fluoride and to compare it with RO-unprocessed (non-RO) water and further to find the association with health hazards such as dental caries and cardiovascular diseases (CVD). Materials and Methods: A community-based observational study was conducted on medical and para-medical staff families. For qualitative data, the Pearson's Chi-square test and for quantitative data, Student's t and ANOVA tests were applied. Pearson correlation coefficient was calculated to know the correlation between TDS and hardness of water and represented in a Scatter Diagram. Results: Out of 466 families, 231 were RO users and 235 were non-RO users. Even after practicing regular servicing of RO unit by the majority RO-users, mean values of TDS, hardness and fluoride were significantly less than RO unprocessed water and were also less than the desired minimum values. Positive family history of dental caries and CVD was significantly associated with the use of RO water. Conclusion: RO process diminishes the chemical quality of drinking water in terms of TDS, hardness, and fluoride and is associated with health hazards. Standardization of chemical quality of RO purifiers for domestic use is equally important as it is being carried out commercially.