Harvested rainwater is an increasingly important water source for households in non-urban regions, especially in areas having no/limited access to municipal supplies. While often considered environmentally sustainable, rainwater quality can vary significantly depending on the collection and storage conditions. Rainwater harvesting is a common practice in rural and peri-urban regions of New South Wales, where properties often rely on private water tanks for household consumption, including drinking. Unlike the municipal water systems, these domestic collection setups are typically unregulated, leaving them susceptible to a range of quality issues, including microbial contamination and chemical imbalances. This study presents a one-month pilot investigation of rainwater quality at a domestic property in Grose Wold, a rural locality in outer Sydney. Weekly samples were collected from an underground rainwater tank used for drinking water and analyzed for key parameters, including pH, dissolved oxygen (DO), biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total organic carbon (TOC). These variables provide a composite view of rainwater quality from chemical and organic perspectives. This preliminary assessment offers groundwork for a broader, multi-site study of harvested rainwater systems across the Sydney region, contributing toward more informed risk management strategies in decentralized water use.