RAINWATER QUALITY: EFFECTS OF STORAGE AND FILTRATION

Abstract

Water quality is an extremely hot topic these days. With continued population growth and strained water supplies it is likely to become even more so. It is estimated that already one in five homes have some type of water filtration or purification system installed. The bottled water industry is also experiencing a boom. Rapid water scarcity and quality concerns are surely some of the factors driving growth of rainwater harvesting. Rainwater is mineral-free. However, once it hits the ground, it picks up minerals from anything it touches. But the quantity of minerals and other substances it uptakes is uncontrollable, in fact, it is minimal. Drinking distilled water, especially if one does not supplement it with a mineral supplement, will tend to cause mineral deficiencies. For this reason, a study was carried out to know the effects of storage and filtration on rainwater quality. The study was carried out taking pure distilled water (presuming rainwater to be pure) and monitoring the water quality changes when exposed to a suitable media. Media chosen was well graded sand from Ranipur near Haridwar (India). Mechanical analysis of the sand was carried out. Size of sand chosen was having properties viz: effective size and uniformity coefficient, as used in slow sand filtration. Though aim here was not entirely filtration but to see quality changes in rainwater. Both batch and column studies were carried out by taking various quantities and composition of media. Also distilled water and rainwater samples were stored in PVC and cement containers (widely used to store water) for long to see the quality changes in various parameters. Various parameters checked were conductivity, pH, UV absorbance, turbidity, major cations and anions and total and feacal coliforms. These parameters were then compared with specifications of IS 14543:2004 i.e. Indian Standard Code for Packaged Drinking Water (other than packaged natural mineral water). From the batch and column studies it is concluded that there is certainly an uptake of minerals by water as the conductivity increased depending on detention time and quantity of media it was exposed to. pH did not show any definite pattern. Other parameters viz ; T Rainwater Quality: Effects Of Storage And Filtration turbidity, UV absorbance, coliform detection and as also pH were monitored to ascertain that they should not exceed safe drinking limits as per IS 14543:2004.