Comment by nrdvana | Hacker News Reader

Comment by nrdvana | Hacker News Reader

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I had a house where a brand new copper line corroded and started leaking 2 years from installation, and I don't mean at joints or anything, I mean the local water just ate right through the wall of the pipe. I switched to Pex and was fairly happy with it.

I never did do the research to figure out what was up with the water, but similarly, when I tried inventing my own sump-pump sensor by dipping copper wire into the sump well, it ate the copper wires apart in 3 days. I tried again with stainless rods and discovered that there was about .05 Volt per inch deep I put the sensor, i.e. the stainless rod near the top of the well would be about 2V higher (or lower, don't recall) than the stainless rod that ran to the bottom. Made it kind of annoying to design the circuit.

Looked in to this seriously for a product some years back. Captured ping pong ball floating on the surface of the water hitting a physical limit switch is the way to go. Otherwise ultrasound.

Convenient point for PEX: If copper pipes aren't properly grounded they'll tend to develop pinhole leaks within that timeframe.

Due to galvanic corrosion / electrolysis?

I'm not a plumber, that's what someone told me once a long time ago. But googling some more, systemic pinhole leakage can also depend on several factors like water cleanliness and pH, with some counties finding grounding doesn't cause pinholing and others finding it does.

The subject may be more complicated than my single sentence can capture.

I assume you have a well, not city water? Utilities generally try to adjust their water to be non-corrosive to copper.

If I used well water or had another non-city source, I would do my best to keep copper out of the plumbing and I would minimize brass as well. Stainless steel and plastic, please.

I assume the copper wire was designed as a simple resistive switch? That will cause electrolysis and corrosion. There's an improved design that involves measuring capacitance, which also uses less power. I have a commercial sump pump monitor that works this way.

Yep, but in the end I was able to switch by monitoring the voltage generated by the water on the stainless rods, using a microcontroller. Worked great for a few years until I moved out. Haven't had a sump pump since. (good riddance)

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