Your statement is at odds with what I know about water.
Your saturation index is what drives water’s interaction with the surfaces it touches, not just pH. If the index is too high it will deposit what it’s carrying (scale) and if it is too low it will pick up material from the pipe it’s flowing through (corrosive).
1) That isn’t distinct from PH, it’s a refinement of it?
2) There is theory, and there is practice in the field. What you’re referring to is the equivalent of ‘wet bulb temperature’ for temps. Which is a thing, but water conditions for a given area rarely vary like temperature will - and are in control of the local water treatment plant. What you’re referring to was specifically made to measure and help control these conditions.
If copper piping is allowed by local code, they’ll know - and keep it within these ranges. Areas with water that is not easy to keep within these ranges will also corrode galvanized pipe (commonly used for water in most areas), and will likely also corrode brass fittings and valves (including back flow valves) commonly used in many areas, leaching lead, copper, etc. among other things. Those areas prohibit them by code for that reason.
Copper piping will generally not corrode unless PH is < 6.5 or > 8.5, which is significantly outside what most would consider reasonable water quality.
I personally have a well in an off grid location with 6.2 PH, and use only CPVC for that reason. Where I live, I’ve done some retrofits and replaced 75 year old copper pipe that was good as new inside.
> If copper piping is allowed by local code, they’ll know - and keep it within these ranges.
I think I’m misunderstanding you. Your original comment was “that’s bullshit” but this seems like it’s in rough agreement.
IIUC copper pipe will last for 50-100 years IFF you pass impure water through it. Pure water will eat the pipe. Same with galvanized steel and brass like you pointed out. So the city treated it with _something_ to keep the water from eating pipe (knowing copper pipe is code) and I’ve anecdotally heard that part of that “something” is fluoride.
From my understanding a negative LSI means the water will try to "pick up" atoms/molecules from the container it is in (corrosive). A positive LSI indicates it will lay down atoms/molecules (scale build-up).
A value of negative infinity tells me that pure water is going to eat the pipes.
That being said, I don't know if the LSI scale is well behaved as these values trend towards 0! The values of water purity in the equation seem to dominate both pH and temperature as those values trend towards 0 - no big difference in results if pH is 7 vs. pH is 3 and no big difference if water is frozen or boiling. Temperature can have a big impact for _very cold_ and _very hot_ but then you're dealing with solid water or steam and that doesn't really make sense to me for this model. That probably suggests the equation is only well behaved for a certain range for each value, and I'd suspect 0 is outside the range these equations can model for TDS, Calcium, and Alkalinity. But I can't find anything that defines the ranges the LSI model applies to.
And yet, distilled water tests a 7 with a PH strip, people use copper pipes with distilled water with no major ill effects, and distilled water won't eat it's way through a copper pot either.
You're clearly trolling someone. I guess I'm done wasting my time on you?
Your assertion is that 'pure water' will corrode copper pipe, so it needs to be 'impure' to not do so (using flouride of all things as an example?)
Yet, distilled water - which is as pure water as anyone will ever see outside a lab - doesn't do so to any meaningful extent. And you keep using various clearly inapplicable theory to try to prove a point that is clearly false in the real world.
This has nothing to do with steel wool, after all.
Only acidic water (and strongly so) will damage copper pipe.
Most copper pipe will easily last 50-100 years, if not more.
Flouride isn't added in any sort of concentration that would measurably change water Ph.
And more.