Water Quality in Rainwater Tanks in Rural and Metropolitan Areas of New South Wales, Australia

This paper compares the water quality of rainwater tanks throughout the Sydney metropolitan area to that in rural New South Wales, Australia. The water quality is compared against the Australian Guidelines for Water Recycling (AGWR) to determine if the untreated rainwater from both areas can be considered suitable for non-potable water supply without filtration. Additionally this paper reports on a set of experiments where rainwater collected from a typical domestic roof in Sydney, New South Wales, Australia was treated by a pre-treatment of granular activated carbon (GAC) adsorption filter followed by micro-filtration. The GAC column removed the pollutants through an adsorption mechanism. GAC is a macroporous solid with a very large surface area providing many sites for adsorption and it is this property that makes it an efficient adsorbent. The parameters analysed were ammonia, anions and cations, heavy metals, nitrate and nitrite, pH, total hardness, total organic carbon, total suspended solids and turbidity. The results indicate that before treatment, the rainwater already complied to many of the parameters specified in the AGWR, certain pollutants have the potential at times to exceed the AGWR. The water quality was within the AGWR limits after the treatment. The micro- filtration flux values demonstrate that rainwater was able to be filtered through the membranes under low gravitational heads that are typically available in a rainwater tank while still producing sufficient membrane flux and pollutant removal rates