I think it may be a common topic/question, but I never found anything here that would explain which solution works with Smartthings well and is cheap.
So I was able to setup a water shutoff when water leak is detected and thought I would share. You can see the video here (at least until my google photos are full):
I use Smartthings hub obviously,
4 Smartthings Water Leak sensors (maybe other cheaper sensors work as well?): https://www.amazon.de/Samsung-GP-U999SJVLCEA-SmartThings-Water-Sensor/dp/B07XZ833L2/ref=sr_1_2?__mk_de_DE=ÅMÅŽÕÑ&dchild=1&keywords=smartthings+water+leak&qid=1602940938&sr=8-2
And what is the most important thing, Zigbee Water Valve actuator from aliexpress. (https://www.aliexpress.com/item/4001038902712.html?spm=a2g0s.90423126.96.36.199d134c4dMc4r1U)
Be careful, first time I bought one from “Moes” seller and unfortunately got a wifi “smart life” version, even though description said “zigbee”. From the link above i got a zigbee version.
I added the valve into the smartthing app (it found a “Thing” without any features), and then modified a handler to “Zigbee Valve”:
Now in Smartthings app I get the valve and the integration with Smart Home Monitor as expected.
Also what is important, all sensors and valve actuator is processed locally (didn’t try without internet but I expect it to work). [CORRECTION: According to JDRoberts it’s not processed locally - see below]
Hope it helps anybody looking for a clear solution to water shutoff automation,