Impacts of pipe materials on densities of fixed bacterial biomass in a drinking water distribution system

Densities of fixed bacterial biomass were measured on different pipe materi als (PVC, PE, cemented steel, asbestos-cement, cemented cast iron, tarred s teel and grey iron) incubated in drinking waters from different sources (gr ound waters and a surface water) which had different characteristics (tempe rature, concentration of residual oxidant and content of biodegradable orga nic matter). Results showed that the densities of bacterial biomass fixed o n plastic-based materials (PE and PVC) were the lowest. Densities of bacter ial biomass fixed on gray iron were from 10 to 45 times higher than those m easured on plastic-based materials. Cement-based materials had intermediate values. Pairs of cement and PVC coupons were incubated at 15 different loc ations in a distribution system, and there was a strong correlation between the amount of fixed bacterial biomass on these coupons, with the cement co ntaining 2.6 times more biomass. (C) 2000 Elsevier Science Ltd. All rights reserved.