(June 20, 2008) — Plastic plumbing pipe contains no lead. Therefore, your recent [June 9, Page 9] story, “Plastic pipes may indirectly pose lead woes,” is a huge leap from any reality since it appears to blame lead extraction on the use of plastic pipe.
In effect, the referenced experiment, partially funded by the Copper Development Association, created an artificial water world where water without disinfectant was used to farm bacteria in pipes by deliberately fertilizing the water with ammonium sulfate. In short and at best, the experiment does not represent real-world conditions.
Its most dramatic shortcoming is its failure to recreate what actually happens in plumbing systems that are treated with chlorine, chloramines or may be disinfected in other ways.
Another significant shortcoming of the experiment is its insufficient duration. Its conclusions are based on the absence of a biofilm on the copper after 200 days. A biofilm had formed on the plastic, lead and brass by that point, but not on the copper.
Biofilm formation is a normal process common to all piping systems and equalizes just past 200 days. Since the copper itself is toxic to aquatic life, including the bacteria studied by this experiment, the water in the experiment's copper systems maintains a higher (less acidic) pH than the water in plastic (chlorinated PVC), lead and brass systems. Hence, the bacteria enhancing nitrification had free reign in the test — in a normal plumbing system using chorine or chloramines, the bacteria would not develop, or, at least, would be kept in check.
There's no reason to believe water pH would normally change dramatically in the real-world as it apparently did in the experiment. The water pH is more likely to be highly variable due to the source of the water than the impact of the bacteria under any conditions.
We hope everyone will keep in mind that the best way to avoid lead contamination in plumbing systems is to use products that do not contain lead. Blaming nonlead containing products for lead contamination just won't cut it.
Plastic Pipe and Fittings
Glen Ellyn, Ill.