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Aims: This study investigated the influence of water chemistry on copper solvation (cuprosolvency) by pure culture biofilms of heterotrophic bacteria isolated from copper plumbing. Methods and Results: Heterotrophic bacteria isolated from copper plumbing biofilms including Acidovorax delafieldii, Flavobacterium sp., Corynebacterium sp., Pseudomonas sp. and Stenotrophomonas maltophilia were used in laboratory coupon experiments to assess their potential for cuprosolvency. Sterile copper coupons were exposed to pure cultures of bacteria to allow biofilm formation and suspended in drinking waters with different chemical compositions. Sterile coupons not exposed to bacteria were used as controls. After 5 days of incubation, copper release and biofilm accumulation was quantified. The results demonstrated that cuprosolvency in the control experiments was influenced by water pH, total organic carbon (TOC) and conductivity. Cuprosolvency in the presence of biofilms correlated with the chemical composition of the water supplies particularly pH, Langeliers Index, chloride, alkalinity, TOC and soluble phosphate concentrations. Conclusions:The results suggest water quality may influence cuprosolvency by biofilms present within copper plumbing pipes. Significance and Impact of the Study: The potential for water chemistry to influence cuprosolvency by biofilms may contribute to the sporadic nature of copper corrosion problems in distribution systems.

Aims: To survey bio®lm accumulation within domestic copper plumbing pipes in South Australian drinking water distribution systems and examine its role in copper solvation (cuprosolvency). Methods and Results: Cold water copper pipes were sampled from two different plumbing systems receiving ®ltered and un®ltered potable water respectively. Biomass was quanti®ed by total organic carbon measurements and viable cell counts and microbial activity by respirometry. Bio®lm accumulation was related to water chemistry within the systems, particularly nutrients, alkalinity and conductivity, as well as water turbulence. Laboratory coupon experiments were used to determine the effect of extracted bio®lm on copper solvation. Bio®lms were shown to be capable of both increasing and decreasing aqueous copper concentrations in comparison to sterile controls. Conclusions:The results suggest that water quality may in¯uence the accumulation of bio®lms in copper plumbing systems, as well as potential cuprosolvency activity. Signi®cance and Impact of the Study: The presence of bio®lms in copper plumbing systems and their ability to in¯uence aqueous copper concentrations has implications for both public health and the management of distribution systems.

Aims:  In vitro experiments were undertaken to evaluate biocide formulations commonly used in cooling water systems against protozoa previously isolated from cooling towers. The investigations evaluated the efficacy of these formulations against amoebic cysts and trophozoites. Methods and Results:  Laboratory challenges against protozoa isolated from cooling towers using chlorine, bromine and isothiazolinone biocides showed that all were effective after 4 h. The presence of molybdate and organic phosphates resulted in longer kill times for bromine and isothiazolinones. All treatments resulted in no detectable viable protozoa after 4 h of exposure. Conclusions:  The chemical disinfection of planktonic protozoa in cooling water systems is strongly influenced by the residence time of the formulation and less so by its active constituent. Bromine and isothiazolinone formulations may require higher dosage of concentrations than currently practiced if used in conjunction with molybdate‐ and phosphate‐based scale/corrosion inhibitors. Significance and Impact of the Study:  Cooling water systems are complex microbial ecosystems in which predator–prey relationships play a key role in the dissemination of Legionella. This study demonstrated that at recommended dosing concentrations, biocides had species‐specific effects on environmental isolates of amoebae that may act as reservoirs for Legionella multiplication in cooling water systems.