That happened in my house when prior owners lived here. Crazy expensive. My parents attic HVAC drip pan overflowed and caused $15k damage about 10 years ago and that prompted me to buy a bunch of leak sensors for my home and an automated water valve.
And dishwasher and attic hvac drip pans.
Here's my full list of locations:
I think I have 14 leak sensors.
Yeah, plastic lines are junk (long term) - Either plan to replace them every 10 years, or have good homeowners insurance. - Even steel braded lines, still just have a rubber hose internally that will eventually fail (10-15 years?) for clothes washers, dishwash, fridges, and toilet/sink lines. So setup a schedule to replace those.
If you really want to get serious, dishwashers and fridges should all be copper lines, and rigid/hard plumbed stainless/copper lines to toilets and sinks - definitely harder to install but should last 40-50 years.
For my upstairs clothes washer, I use a Watts water stop (horrible to install), TR sensor + Hubitat contolled water main value, and See: https://www.amazon.com/Watts-Intelliflow-Washing-Machine-Shutoff/ and I used FloodChek hoses which I'm set to replace in 20 years - Not sure if they are still in business (https://www.tjsradiantheat.com/assets/FloodChek1.pdf)
And lots of Zooz and TR water sensors for hot water heater, sinks, etc - Total of about 15 sensors.. Still the weak link is frozen pipes in a winter power failure, but that's all a seperate story.
I forgot to mention the HVAC drip pan, so thanks for the reminders!
In my attic, there is a power outlet reasonably close to the drip pan, so I used a battery converter to replace the AA batteries in my Zigbee water leak sensor, obviating the need to go up there to change batteries.
Heat tape zip tied to the water line on a controlled outlet that turns on when the temperature is below 32F.
Just got my HE-C8Pro the other day and spent all day Saturday moving my devices from ST. I was surprised how easy it was first I removed from ST and then immediately searched on HE and boom. Took some time to complete all 36 devices but it was smooth. Now onto the next phase writing rules. Been mainly using HE basic as most of my rules are simple. I have a few complex ones I will do as soon as I figure out the advanced rules works. So far the only issue is with Alexa. When I use voice requests it does the request but then says item is unresponsive even though it was successful in turning on light.
Thank you, where do I find that?
Found it thank you again
If you are not too invested in Rule Machine yet, you may want to check out Webcore for automations. It doesn't get much love but many find it much easier to work with for complex automations.
Many don't know about it, or if they do, they don't want to learn something new. It is also very stable, as it has been around for a decade, starting with SmartThings. It is now a built in app, or you can install it from the Webcore repositories with HPM.
Edit: note, the editor is in the cloud, but all pistons run on the hub locally with no cloud connection needed. I like the cloud editor, personally, as you can bring it up anywhere.
The automated water shut off is the most important part of the the leak sensors installation. My big concern is a leak when we're away. We have a well so a water shut off after the pressure tank and a power shut off for the well pump.
I'm planning on calling or texting my neighbors and have them go in through the garage and shut off the water main. We have great neighbors!
It's always nice to have a free option.
But sometimes you get what you pay for. 
The damage that can be done before you even find out could be considerable. My water is shut off in seconds when a leak sensor notifies.
I have sensors so I should find out within minutes. Actually, I just installed my first 4 sensors last week, and I received a notification from the one under the kitchen sink yesterday! I ordered 5 more. I also send text messages to Sonos for an audible notification in addition to my phone. It was a minor leak, the soap dispenser doesn't have a gasket. Nice to get a notice though!
I discussed this with my wife and we plan on shutting off the main when we go away. Other than that someone is here.
I've seen the shutoff devices they do look cool. Are they difficult to install or do you need a plumber? I'm thinking plumber!
If you want an in-line shutoff (especially on the main line), then I'd definitely recommend a plumber unless you are well-versed with DIY plumbing.
I use a Zooz Titan on both my water and main line -- they are awesome, and very easy to install. There are quite a few options for similar devices that all work with a lever-type 1/4-turn ball valve, but if you have a gate or butterfly valve, those are incompatible with these sort of add-on shutoff valves.
Same. It works well as long as you have good ball valves!
No automated watering?
You need to interrupt the main water line. Depends on how handy you are. It is happens to be a 90 deg lever valve something like this will work well. Amazon.com
No, we've never watered when away. It's never been a problem.
