Variability in the concentration of lead and copper sampled at consumers' taps poses challenges to assessing consumer health threats and the effectiveness of corrosion control. To examine the minimum variability that is practically achievable, standardized rigs with three lead and copper containing plumbing materials (leaded brass, copper tube with lead solder, and a lead copper connection) were deployed at five utilities and sampled with regimented protocols. Variability represented by relative standard deviation (RSD) in lead release was high in all cases. The brass had the lowest variability in lead release (RSD = 31 %) followed by copper-solder (RSD = 49%) and lead-copper (RSD = 80%). This high inherent variability is due to semi-random detachment of particulate lead to water, and represents a modern reality of water lead problems that should be explicitly acknowledged and considered in all aspects of exposure, public education, and monitoring.

Cumulative changes in chemical and biological properties associated with higher "water age" in distribution systems may impact water corrosivity and regulatory compliance with lead and copper action levels. The purpose of this study was to examine the effects of water age and chemistry on corrosivity of various downstream premise plumbing pipe materials and configurations using a combination of controlled laboratory studies and a field survey. Examination of lead pipe, copper pipe with lead solder, and leaded brass materials in a replicated lab rig simulating premise plumbing stagnation events indicated that lead or copper release could increase as much as ∼440 % or decrease as much as 98 % relative to water treatment plant effluent. In field studies at five utilities, trends in lead and copper release were highly dependent on circumstance; for example, lead release increased with water age in 13 % of cases and decreased with water age in 33 % of conditions tested. Levels of copper in the distribution system were up to 50 % lower and as much as 30 % higher relative to levels at the treatment plant. In many cases, high-risks of elevated lead and copper did not co-occur, demonstrating that these contaminants will have to be sampled separately to identify "worst case" conditions for human exposure and monitoring.

Many water utilities add zinc orthophosphate to treated water to reduce corrosion of plumbing materials within their distribution systems. The significance of zinc as a corrosion inhibitor was examined in bench‐scale tests of concrete corrosion. In waters with low hardness and low alkalinity, zinc orthophosphate provided better corrosion inhibition for concrete or cement‐based pipes than either zinc or orthophosphate alone. Addition of orthophosphate alone was beneficial in reducing the amount of scaling in waters with high hardness and high alkalinity.

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This article discusses a testing program initiated by a Lake Michigan water utility to study the occurrence of an aluminum‐phosphate compound in its distribution system, and to examine strategies to control it while maintaining optimized lead levels. Experimental methods included continuous feeding of pipe‐loop systems, using a programmable controller, at a predetermined constant flow rate for 16 hours, followed by eight hours of no flow to simulate stagnant conditions. To reduce aluminum levels in the finished water, phosphoric acid was fed at the rapid mix to combine with the residual aluminum. Data is provided on the typical raw and finished water quality, which demonstrate the reduction of aluminum and phosphate levels to minimize deposition.