LSI seems to trend towards negative infinity as TDS et. al. approach 0.

    pH = 7 (pure water)
    TDS = 0 mg/L
    Calcium = 0 mg/L (or ppm) as CaCO3
    Alkalinity = 0 mg/L (or ppm) as CaCO3
    Temperature = 21 celsius (room temp)

A = (Log10 [TDS] - 1) / 10 = (Log10 [0] - 1) / 10 = -Infinity

B = -13.12 x Log10 (Temp + 273) + 34.55 = -13.12 x Log10 (21 + 273) + 34.5 = 2.12

C = Log10 [Ca2+ as CaCO3] - 0.4 = Log10[0] - 0.4 = -Infinity

D = Log10[alkalinity as CaCO3] = Log10[0] = -Infinity

pHs = (9.3 + A + B) - (C + D) = 9.3 + A + B - C - D = 9.3 - Infinity + 2.12 + Infinity + Infinity = Infinity

LSI = pH - pHs = 7 - Infinity = -Infinity

https://www.wolframalpha.com/input?i=7+-+%28%289.3+%2B+%28%2...

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.

Can’t tell if you’re trolling me at this point.

I wonder what you think the pH of steel wool is. I bet you could place steel in a copper pot and it won’t eat through it.

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.

Lol don’t you love it when you give a smack down with math?