Copper is a well known bacteria killer in water. Typically Pex is used for most plumbing with copper ends. Older construction will have all copper indoor piping

I didn’t know that. I assumed that my Pex always terminates to copper because that’s basically the common interface for all fixtures being sold. But you’re suggesting it’s actually bacterial related? Or was that just a fun fact?

I have a mixed system of PEX / Copper in my basement since they used that when installing the water softener. The pipes sweat during the summer and this resulted in mold on the PEX pipes. Copper pipes seem to resist it, which wasn't to surprising. I've heard copper top strips are sometimes used on roofs because the run off prevents moss and other things from growing atop the roof.

PEX is banned in California. I think most other states its normal now.

PEX was banned, but the ban was lifted in 2010.

Why was it banned originally?

Oof:

> Contamination of drinking water The PEX EIR found that methyl tertiary-butyl ether (MTBE) and tert-Butyl alcohol can leach from PEX in amounts that exceed taste, odor and health guidelines set by the State of California for drinking water. The PEX EIR found that PEX pipes can initially leach as much as 290 ppb of MTBE. The California Department of Public Health and the California Office of Health Hazard Assessment have established a drinking water taste and odor standard of 5 ppb for MTBE and a drinking water public health goal and maximum contaminant level of 13 ppb. One of the key issues for the California State Pipe Trades Council was the recognition that construction workers are often the first to consume water from newly installed pipes. Because the levels of MTBE contamination from PEX pipe are highest during the first month of use, workers were at risk of repeated exposure to drinking water contaminated with MTBE at levels exceeding public health goals as they moved from job site to job site. The PEX EIR found that, unlike copper pipe, outside contaminants such as pesticides, oil, gasoline, and benzene can permeate through PEX pipe into drinking water. Several studies and articles comparing potable water pipe materials, including variants of PEX, polybutylene, polypropylene, CPVC, copper and steel, have found that PEX, at least initially, displayed the strongest biofilm formation and the strongest promotion of the growth of Legionella bacteria.

> pesticides, oil, gasoline, and benzene can permeate through PEX pipe

The lifespan of plastic pipe designed to be carrying water (ie: non-polar) exposed to these polar solvents has gotta be terrible.

(Since like-dissolves-like, you want your water pipes to be made of a polar material so that water doesn't dissolve it).

Pretty sure you got that backwards. Water is a polar molecule.

oh yeah, I screwed up my last sentence.

for clarity, in "plastic pipe designed to be carrying water", the plastic pipe is non-polar. Yes, water is polar, which is why you want it carried in something non-polar, because like-dissolves-like.

it's funny because you can make the same arguments against freshly brazed lead connections on copper pipes. And those "low lead fixtures" aren't lead-free.

Does plumbing solder still contain lead?

hrmmm, looks like plumbing solder has been banned (for sale I guess) since 1986 in USA and since 1990 in Canada. US regs are specific to potable water lines, so unclear how available it is.

(Wouldn't be surprised if plumbers stocked up on several years worth prior to the bans).

Oh good to know, thanks for looking that up.

And even worse, have pesticides and other stuff from pipe surroundings leech through plastic into water.