Unterstinkenbrunn is a town in the district of Mistelbach in the Austrian state of Lower Austria.
The water from the Stinkebrunnen well, from which the village takes its name, is enriched with ferrous iron salts from the clay and sand soil, which oxidises to ferric iron upon contact with atmospheric oxygen, giving the water an inky taste, sulfurous smell, and the wellhead an extensive layer of red dust.