Guidance on use of rainwater tanks

Accumulated sediment

Page last updated: March 2011

Sediments accumulated below good quality rainwater can contain high concentrations of chemicals, including lead (Gee 1993; Scott & Waller 1987; Coombes et al. 2002b). In a survey of water and sediment samples from tanks along the rail corridor used to transport lead ore to Port Pirie, very high concentrations of lead were detected in the sediments, while most of the water samples (25 of 33) contained less than 10 g/L (Body 1986).

Sediments could be particularly significant in the absence of regular cleaning, as taps are typically close to the bottom of tanks. There have been examples where elevated concentrations of lead have been detected in samples taken from tank taps, due to the presence of small amounts of re-suspended sediment from the bottom of poorly maintained tanks (South Australian Department of Human Services, unpublished results).