1st International Conference on Rain Water Cistern Systems
Honolulu, Hawaii, USA - June 1982

Section 4: Water Quality

Page 249

Occurrence of Selected Heavy Metals in Rural Roof-Catchment Cistern Systems

William E. Sharpe & Edward S. Young
The Pennsylvania State University, USA

Introduction

Roof-catchment cistern systems consist of a roof, usually the house roof, which serves as an impervious catchment for precipitation, and a cistern to store the collected water. The stored water is pumped from the cistern to points of use within the house. Very little is known about the prevalence of this type of water supply in the United States or the quality of drinking water obtained from such systems. A recent paper by Kincaid (1979) cites Ohio Department of Health records that reported a total of 67,000 cistern systems in the state of Ohio alone. A company owned and operated by Mr. Kincaid specializes in providing service to cistern owners in Ohio. The company handles approximately 800 requests for assistance each year and provides specialized water treatment equipment to its customers. Since mot of this equipment is designed to remove particulates and disinfect cistern water, it may be concluded that these are important cistern water quality problems. However, the relatively new phenomenon of acid rain (Cogbill and Likens 1974). and the deposition of toxic metals such as lead (Lazrus et al. 1979; Hutchinson 1973) in roof-catchment cistern systems have not been previous investigated.

Roof-catchment cisterns are common in regions of the United States where groundwater supplies are either unavailable or unusable. Cisterns are present in the coal mining regions of Pennsylvania where ground water has been polluted by mining and public water supplies are unavailable. Additional concentrations of these systems occur where groundwater has not been successfully developed and surface water sources are either polluted or nonexistent. The former case generally prevails in rural areas of Clarion on and Indiana Counties, Pennsylvania and in much of southeastern Ohio.

Although each cistern system was unique, most cisterns were constructed of concrete or cinderblock coated with a waterproof cement-base sealant. Sixteen of the 40 systems evaluated in 1980 incorporated sand and gravel filters to remove particulates from incoming precipitation. In those systems with sand and gravel filters, CaC03 may have also been added as the precipitation passed through the filter.

A study was designed to survey water quality in roof-catchment cistern water systems to determine the occurrences of the toxic metals, lead, cadmium and copper. A related objective involved the evaluation of the corrosivity of the water being collected and stored in roof-catchment water systems and its relationship to plumbing type, cistern construction materials and water treatment devices.

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