A study of private wells in rural Nova Scotia found that concentrations of metals such as cadmium, zinc, copper, and lead increased in water that remained in the distribution system overnight. Some 50 percent of the homes studied exceeded Canada's recommended 1.0‐mg/L maximum permissible limit for copper and 20 percent exceeded the 0.05‐mg/L limit for lead. Metal mobilization was observed in all four of the communities studied, regardless of differences in well water chemistry. Significant leaching was observed in water of high pH and hardness. Four indexes commonly used to assess the corrosive tendency of a water did not accurately predict the metal leaching that could occur in a given water.

This paper provides an overview of the results of a study undertaken to provide a basis for predesign evaluation of the effectiveness of options for treatment of municipal surface waters in the province of Nova Scotia. Seasonal samples of raw water were obtained from the fall of 1992 through the fall of 1993 from five sites. Results were compared with a Nova Scotia Department of Health data base of randomly collected samples. For project samples, strong relationships were evident between raw water total organic carbon (TOC) and both colour and trihalomethane formation potential. Laboratory batch tests, supported by plant results, indicated that percentage removals of TOC increase with raw water TOC, and that settling-filtration was more effective than direct filtration for waters with higher raw TOC concentrations. Results of solids settling tests were consistent with TOC results. A treatment optimized for TOC removal also ensured removal of colour. TOC removals by dissolved air flotation followed by filtration exceeded removals by direct filtration or settling-filtration, based on laboratory bench tests, particularly at sites with higher values of raw TOC. Colour removal by dissolved air flotation was consistently higher at all sites. Key words: enhanced coagulation, trihalomethane precursors, total organic carbon, surface water treatment, dissolved air flotation.

Studies were made of the mobilization of metals from the water-distribution systems within several types of buildings, many of which are serviced by old leadpipe mains, in Halifax, Nova Scotia. The study examined 36 single-family houses, three apaftments in a high-rise building, and one school. ln many homes, water that stood in pipes overnight developed relatively large concentrations of copper, lead, and zinc. In total,TQ'h of the standing water from single-family homes had lead concentrations exceeding the 0.01 mg/L criterion for lead in drinking water.The 30 single{amily homes serviced by municipal mains made of lead did not have significantly larger lead concentrations than the six homes serviced by other types of piping. This suggests that the source of lead in drinking water is metal dissolving from the water-distribution systems within the homes, rather than from the lead service lines. R6sum6Une 6tude a 6t6 faite sur la mobilisation des m6taux d partir des systdmes de distribution d'eau, dans divers types d'6difices d Halifax en Nouvelle-Ecosse, oit de nombreaux 6difices sont desservis par d'anciennes conduites d'eau en plomb.Cette 6tude a examin6 36 maisons unifamiliales, trois appartements dans un immeuble, et deux 6coles. Dans de nombreuses maisons, l'eau stagnants dans les tuyaux pendant la nuit a acquis des concentrations relativement importantes en cuivre, plomb et zinc. Au total, dans 7O"/" des maisons unifamiliales, ces eaux stagnantes avaient des concentrations en plomb exc6dant le critdre pour les eaux potables (0,01 mg/L). Les 30 maisons unifamiliales desservies par des conduites municipales en plomb n'ont pas mont16 de concentration en plomb significativement plus 6lev66 que les 6 autres maisons desservies par d'autres types de conduites. Ceci suggdre que le plomb d6cel6 dans l'eau potable provient du m6tal se dissolvant apartir des tuyaux d'eau dans la maison elle-m6me plut6t qu'd paftir de la conduite municipale.

received a B.A. in Biology and M.Ed. from Rhode Island College and is currently teaching Chemistry, Biology, and Fuel Cell classes at Ponaganset High School in Glocester, Rhode Island. An advocate of renewable energy and founder of the Fuel Cell Education Initiative, he strives to bring unique and exciting learning opportunities to students that effectively demonstrate renewable energy technologies.