Looking for expertise on electrochemical corrosion of water pipes

I am evaluating the source of elevated lead and copper in water from a water supply system that includes municipal distribution, local distribution, and building piping. Building piping is the likely source of the metals and electrolysis is a anticipated to be a potential mechanism. Is there a way to pinpoint where electrolysis is occurring in the pipe? The water first out of the tap had lower concentrations of copper in it than what was collected after purging 1.3L out of the pipe. To me this suggests that electrolysis occurs further down the pipe. Thanks.

 

[mcguire]

Your data excludes the source as being in the last length of pipe that holds 1.3L, but it doesn't confirm that the water after 1.3L picked up the copper and lead at that point where it was residing when you turned on the flow.
I think you need to take samples upstream until you get to a point at which no amount of flow yields copper and lead. Or if you purge the system by a lot of flow and then do what you did before, measure the volume out until copper/lead appears you will be able to calculate how far upstream the origin was based on pipe volume. Maybe this is what you did already, in which case the 1.3L will give you the location.