Checking the tank means walking out in the drizzle, climbing up, squinting at the gauge. This Jaycar unit ends that. Mount the transmitter at the top of your water tank and it reads level and temperature ultrasonically — no contact with the water. The receiver hangs on a wall or sits on your kitchen bench on its pull-out stand, up to 100 metres from the tank. A ten-element bar graph shows you exactly how full the tank is at a glance. You also get room temperature, tank water temperature, and min/max storage so you can spot trends. Set high-level and low-level alarms, or an empty-tank alert, and stop wondering if there's enough water before the sprinklers kick on. One heads-up: if you run a second XC0331 within range of the first, you'll get cross-channel interference. Stick to one per property