Sediment Transport in Rainwater Tanks and Implications for Water Quality

Abstract

Prolonged drought and increased water demands because of population growth have led to water storages. In Australia, the introduction of permanent water restrictions in urban areas and water conservation education programs have resulted in increased uptake of rainwater tanks as an alternative water source at the household scale. While there is in-depth understanding of the water savings that can be attributed to the substitution of mains water by water from rainwater tanks, there is limited understanding of the quality of the water and sediment collected in the tanks. This chapter provides information on tank water and sediment quality gained through field work, a laboratory investigation and development of a mathematical model. The layout of this chapter is as follows. Section 1.1 describes the rainwater tanks design while Section 1.2 provides background information for this work on water quality in rainwater tanks in residential areas. Section 2 explains the series of methods employed to collect and analyse the sediment in rainwater tanks, while Section 3 presents the series of results for sediment quality in the tanks, including a summary of the experimental program implemented to understand the factors affecting sediment re-suspension from rainwater tanks, the results of leaching tests and development of a model. The implications of these results on rainwater tanks sediment quality are brought together in Section 4, discussion and 5, conclusions.