> There’s a cheap ($20?) add on for our water heater that adds a conductivity sensor in the drip pan, and a shutoff valve on the inlet.

Oh I know, they are awesome. They should come standard, and more people should know about them. It is one of those things I try to bring up in conversations at random, because holy crap the # of people I know who have had water damage from their water heating dramatically failing is too high. Heck it happened to my family twice while I was growing up.

> the plumbed lines don’t actually help with leaks; so they do nothing that a garden hose would not accomplish.

Why not? I've seen places where with a drip pan angled towards a hole connects to a pipe that drains outside.

It should work for slow leaks. Doesn't do anything if the tank bursts of course...