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Comment by allannienhuis | Hacker News Reader

Interesting. Two studies with pretty much conflicting conclusions about safety of copper for potable water. I imagine that there is a level (range) of exposure that is in the sweet spot between 'kills harmful microbes' and 'kills/harms humans who drink the water'.

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One study is abut storing water in copper pots and the other is about copper in drinking water. Does storing water in pots automatically mean that the copper goes into the water and if yes, how high is the concentration?

TFA looked at the copper concentration in the water after storage and it was below WHO guidelines for safe copper levels. Whether the WHO guidelines are sufficient or not is another question.

The WHO guideline for copper is 2mg/l which is the same as in the German guidelines "Trinkwasserverordnung". The article linked by batter says right in the abstract:

We found that the disease can even be caused by copper concentrations below the allowed concentration given by the German Guidelines for Drinking Water (Trinkwasserverordnung).

>Does storing water in pots mean that Cu goes into water

It's not automatic, but depends on pH. Acidic conditions will be favorable to metals leaching into water. The paper cites an initial pH of 7.84, and final pH of 7.94 - so the pH increased slightly as a result of the copper entering the solution.

This pH change correlated with 177 ppb Cu concentration in these pots after 16 hours. If initial pH was lower this concentration would see a logarithmic increase in relation the lower initial pH over the same time interval.

"Since distilled water is slightly acidic (pH 6.7±0.05) which might enhance copper leaching, we have demonstrated the effect of copper pot in regular drinking-water"

A quick google says: Drinking water in the US of A must have at least a pH of 6.5. They should have tested with that.

I assume, the copper concentration would increase over 10-fold in that case versus the tested case.

How is storing it in copper pots significantly different than "storing" it in the copper pipes prevalent in a majority of houses in the USA?

That's true for houses of a particular age and value. New stuff is all PEX, and has been for some time. Old enough houses would have been cast iron. Cheaper houses (mobile homes, for example) were all PVC for a long time.

I had to dig up and repair a sewer pipe yesterday, and was somewhat surprised to find that it was made of clay tile.

in Los Angeles county (and, I believe, LA City), clay pipe is still an approved material for sewer pipe laterals

http://dpw.lacounty.gov/general/faq/index.cfm?Action=getAnsw...

http://library.amlegal.com/nxt/gateway.dll/California/lamc/m....

'icantdrive55 the thread is about water supply lines, not boilers or HVAC evaporator coils. I've dealt with a number of plumbers over the last several years, and not one wanted to use anything but PEX for supply lines. Actually a different preference would be a strike against any plumber I'd consider hiring for new work. Also you appear to be hellbanned.

That's a pretty wacky position.

The only meaningful strike against copper is commodity cost.

Of course they wanted to use PEX. It's cheaper and easier for them to install, since they don't have to solder anything. But there are definitely some concerns about PEX. http://www.calpipes.org/ProtectingCalifornians_PEX.asp It leaches a lot of chemicals which may or may not be harmful, but which certainly do cause an odor. It is permeable to some pesticides, oil, gasoline, and benzene. It is not anti-microbial like copper is, which means you get biofilms. If it's exposed to sunlight for two weeks (perhaps because some contractor left it outside), its chlorine resistance disappears. It is not recyclable, and makes toxic smoke when it burns. But it is 1/3 the cost. Your choice.

Eh, what is the expected lifetime of PEX tubes?

The building code in USA is a bit relaxed compared to northern Europe, but can you have PEX tubes inside walls?

I think the recommendation here is a dual tube system, with a PEX pipe inside a protective outer tube.

I think the typical warranty is 25 years? With all the lawsuits the EIFS people faced, one would expect most manufacturers to be very sure about this sort of thing...

Yes, you can have PEX enclosed in finished walls in most US cities. Only need to sheath when subject to damage (e.g. Passing through potentially abrasive material)

Our main sewer line is Orangeburg. I look forward to replacing it soon.

New stuff is not all PEX. Some people prefer copper because of its anti-microbial properties and because it's a known quantity that has been used for a very long time. PEX was only even approved in California in 2009, and there was a lawsuit about the stuff it was leaching into the water. Whether it's safe is controversial. Whether it's stinky is not-- PEX causes the water to smell bad. https://www.purdue.edu/newsroom/releases/2014/Q4/drinking-wa...

Also, nobody cares what sewer pipes are made of. Cast iron is a popular choice, but it could be just about anything, since you're not drinking the water (one hopes.) In California, they even used to make them out of pressed wood pulp and pitch in the 1960s... another wonder material that turned out to be not so wonderful in the long term... https://en.wikipedia.org/wiki/Orangeburg_pipe

I guess it was still better than cement-asbestos pipe, though. Which is still used to supply tap water in some cities. :( Another wonder material of a bygone era.

Good point, probably similar I imagine

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