I assume there’s a factual answer. Mods, feel free to move this if there isn’t.
Our 15-year-old Insinkerator Hot Water Dispenser started leaking yesterday and my wife decided to see if we could fix it. Spoiler alert… we’re heading out to Lowes to buy a new one later today.
We opened up the tank since it seemed to be leaking at the gasket where the top and bottom of the tank attach with screws. When we looked inside we saw a large amount of a white cakey substance. I wasn’t about to taste it, but it looked to me like salt. If it matters, we have a Culligan water softener that I regularly supply with pellets and we have always been on city water, not a well.
I suppose it could just be salt that has precipitated out over the years since the dispenser is kept at a constant 190 degrees F.
Is it likely to be NaCl, or could it be something more nefarious? Should I be at all concerned or is this “normal” given the age of the appliance?
Calcium, lime or “scale” in general is probably all it is. If it’s to the point that it’s breached gaskets and is causing leaks, it’s probably a lost cause, but CLR or vinegar will often do a pretty good job of cleaning it up.
Of course, if it lasted more than a few years, it’s probably not worth the trouble of doing any kind of preventative maintenance on it.
On the other hand, if you notice water coming out (not leaking) slower than usual or it was taking longer to heat over the last few weeks/months, you could watch for that to happen again and know that you’re on borrowed time and it might be worth trying to clean it up then, before it breaks. Mineral scale building up in the spigot, causing the water to slow down may be a good warning sign that it needs attention (or not, I don’t know, I’ve never had one).
Is the thing connected to your water softener? Many households don’t connect it to the cold water side of the kitchen sink so that drinking water doesn’t get the sodium from the softener.
If the water going to the dispenser isn’t softened, the scale will mostly be calcium carbonate.
Few people have seen calcium, the element. It looks like aluminum, but reacts with water forming calcium hydroxide.
As said, it is almost certainly calcium carbonate. Chloride salts, including table salt (NaCl) or other salts used as water softeners (KCl, MgCl2), are more soluble at higher temperatures. So you wouldn’t generally see precipitate on the hot water side. However, the solubility of calcium carbonate and calcium sulfate decreases as the temperature goes up, so you’ll see scale on the hot water side first.
If your water dispenser uses unsoftened water, you’re seeing the carbonates or sulfates precipitate out - these are what defines “hard water”. If it’s softened water, then it’s likely calcium sulfate, which is a common impurity in cheaper water softener salts.