A tank usually runs out at the worst time. A rainwater tank drops below the pump intake, a diesel day tank needs a site visit, or a grain silo is lower than expected before the next delivery. A low-cost distance sensor can prevent most of that guesswork. Dragino distance sensors are a practical way to measure level without putting electronics into the liquid or stored material. Mounted at the top of a tank, silo, or bin, the sensor measures the empty space between itself and