The Roost Smart Leak and Freeze Detector will tell you if your basement's flooding or if a pipe bursts. It uses an alarm and mobile alerts.
The Roost covers a larger area thanks to the dual coiled probes on the bottom of the device.
The blue rubber bottom stops the Roost from sliding around easily.
The Roost is a solid device for only $50 (that's about £40 or AU$65). If you don't have a smart hub such as SmartThings or Wink, it's one of the best sensor options out there.