2nd International Conference on Rain Water Cistern Systems
St Thomas, Virgin Islands - June, 1984

Section E: Quality Considerations

Paper E.1

Heavy Metals In The Drinking Water From Cisterns Supplying Single-Family Dwellings On St. Maarten Netherlands Antilles

Antonio F. Gumbs
Department of Environmental Regulation Florida, USA

Forrest E. Dierberg
Florida Institute of Technology USA

Abstract

The concentrations of zinc, lead, chromium and cadmium in 46 cistern water supply systems from single-family dwellings on St. Maarten, Netherlands Antilles, were evaluated with respect to U.S. drinking water standards. These heavy metal concentrations were considerably below U.S. drinking water limits Samples from kitchen taps showed release of zinc, lead and cadmium had occurred in t -e distribution system (pressure tank and supply lines) with lead and cadmium exceeding the U.S. drinking water standard for 6.5%: and 2.2% of the cisterns, respectively. The release of these metals in the distribution system was not related to the corrosiveness of the cistern water.

Inputs of zinc and lead from aerial and corrosion sources were removed from the water column to the cistern sediments. Substantial increases in pH, calcium and alkalinity occurred as the unbuffered and corrosive rainwater came into contact with the cistern masonry. The cistern water remained mildly corrosive after contact with the concrete structure. The measured concentrations of each metal were in close agreement with the calculated thermodynamic equilibrium concentrations.

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