Rainwater tanks found to harbor bacteria and heavy metals

Research from Adelaide University and Flinders University has identified potential health risks in household rainwater tanks across Adelaide and the Adelaide Hills. Testing conducted on 100 tanks revealed the presence of various bacteria linked to gastroenteritis and other infections, including Campylobacter (13%), Pseudomonas aeruginosa (12%), Salmonella (10%), and Shigella (3%).

Notably, bacteria were detected in tanks used for drinking water, a practice reported by 67% of the households surveyed. Lead researcher Dr Mira Cooper noted that rainwater can collect contaminants such as bacteria and metals as it flows from roofs and through gutters into storage tanks.

In addition to biological contaminants, some tanks contained levels of metals—including cadmium, lead, arsenic, and manganese—that exceeded Australian health-based drinking water guidelines. The study found that metal tanks and those lacking regular maintenance were more likely to exhibit elevated metal concentrations compared to plastic tanks.