I really like the Linkind Water Leak Detector mentioned in Cheap/bulk Water/Leak Sensors? - #33 by erktrek
$17 for 1, or $50 for 4. I got the 4 pack. They work reliably. Still at 100% battery after 9 months. They are Zigbee.
https://www.amazon.com/Linkind-Detector-Required-Wireless-Bathroom/dp/B08YDL4YQ2?th=1
