2015/16: Adelaide “Foothills” (South Australia) – Lead
Higher lead levels were detected most often in the Adelaide foothills. In that area, 51% of samples contained lead above the ADWG, compared with 41% in the Adelaide hills, and 27% in the Adelaide plains…
In addition to lead, the study detected zinc, cadmium, and copper in a few samples that exceeded the ADWG limits. Zinc was above the ADWG of 3.0 ppm in 53 (14.5%) samples. As with lead, the number of samples that exceeded the zinc ADWG limits was highest in the Adelaide foothills, and lowest in the Adelaide plains (Figure 2). It should be noted that the zinc and copper guidelines are guidelines for aesthetic reasons and not health based guidelines . Cadmium and copper were also detected in a few samples. Cadmium was detected in 19 samples (5.2%) above the guideline of 0.002 ppm. The detection of copper above the ADWG of 2.0 ppm was limited to eight samples (2.1% of samples) that were from the same tank located in the Adelaide hills. The concentration of copper detected in the 8 samples ranged from 2.69 ppm to 3.47 ppm. The tank was plumbed-in and a filter installed, and the water used as drinking water…
Lead was the metal of greatest concern detected in rainwater in the Adelaide region above the
ADWG. The presence of lead in rainwater at concentrations above NHMRC guidelines is supported by previous studies…This study found that the concentration of lead in Adelaide rainwater ranged from <0.01 ppm (limit of detection) to 3.24 ppm, which is consistent with studies of other urban areas in Australia…
In Adelaide, it is not clear where the lead found in rainwater samples comes from, although
the relationship detected between lead and both roof material and geographic region might provide some clues. It is possible that the lead comes from the roof material, although lead as a component of galvanized or coated metal roofs is not regularly reported. The lead might be environmental….Zinc was higher in samples collected in the Adelaide hills and foothills, which are also those areas that have higher numbers of galvanized roofing. It is possible that lead and zinc found in rainwater could be linked to a combined corrosive action by solar radiation, wind, weathering, and pollution on rooftop structure materials….
This study indicates that lead was the metal detected in samples above the ADWG most often.
Of 53 tanks surveyed, lead was detected in 47 tanks above the ADWG, in at least one sampling event. Zinc, cadmium, and copper were detected in fewer samples, predominantly in the Adelaide hills and foothills. Lead and zinc in rainwater content was consistent with roof materials and geographic area, although it was not possible to determine which of these effects was the primary contributor, as roof material in the Adelaide hills and Adelaide foothills are primarily, or solely, galvanised metal.”
Lead, Zinc, Copper, and Cadmium Content of Water from South Australian Rainwater Tanks
Chirhakarhula E. Chubaka ID , Harriet Whiley ID , John W. Edwards and Kirstin E. Ross
Int. J. Environ. Res. Public Health 2018, 15, 1551; doi:10.3390/ijerph15071551
Lead Australian Drinking Water Guideline 0.01mg/L
“… Lead can be present in drinking water as a result of dissolution from natural sources, or from household plumbing systems containing lead. These may include lead in pipes, or in solder used to seal joints. The amount of lead dissolved will depend on a number of factors including pH, water hardness and the standing time of the water.
Based on health considerations, the concentration of copper in drinking water should not
exceed 2 mg/L. Based on aesthetic considerations, the concentration of copper in drinking water should not exceed 1 mg/L.
Copper is widely distributed in rocks and soils as carbonate and sulfide minerals.
Copper is relatively resistant to corrosion and is used in domestic water supply pipes and fittings. It is also used in the electroplating and chemical industries, and in many household goods. Copper sulfate is used extensively to control the growth of algae in water storages.
Copper is present in uncontaminated surface waters at very low concentrations, usually less than 0.01 mg/L. The concentration can rise substantially when water with a low pH and hardness remains in stagnant contact with copper pipes and fittings. Under these conditions, the concentration of copper can reach 5 mg/L or higher. In one extreme case overseas, a concentration of 22 mg/L was reported.
Based on aesthetic considerations (taste), the concentration of zinc in drinking water should
be less than 3 mg/L. No health-based guideline value is proposed for zinc.
Zinc is widely distributed and occurs in small amounts in almost all rocks, commonly as the sulfide. It is used as a coating to prevent corrosion of iron and steel products, and in the manufacture of brass. Zinc oxide is an important component in the manufacture of paint and rubber products, including tyres.
In surface and ground waters, the concentration of zinc from natural leaching is usually less than 0.01 mg/L. Tap water can contain much higher concentrations as a result of corrosion of zinc-coated pipes and fittings. Zinc concentrations in galvanised iron rainwater tanks are typically 2 mg/L to 4 mg/L but have been reported as high as 11 mg/L.
Taste problems can occur if the zinc concentration in drinking water exceeds 3 mg/L. Water with a zinc concentration above 5 mg/L tends to be opalescent, develops a greasy film when boiled, and has an undesirable dry ‘metallic’ taste. Zinc is present in plant and animal tissues, and food is the major source of zinc intake. Drinking water usually makes a negligible contribution to total intake. 2011 ADWG