Soluble arsenic salts are an insidious health threat to countless people who rely on wells for drinking water, particularly on the Indian sub-continent, where skepticism of tubewells in the 1960s and onwards as offering the "devil's water" have revealed a chilling truth. Now, European researchers have devised a simple and, critically, inexpensive filter that can remove arsenic salts from drinking water. The filter uses iron oxide-coated sand which absorbs the arsenic from water at the source. The device could be cheap enough for even the poorest families in affected regions of the developing world to afford. Furthermore, there are potential users in wealthier places too, such as remote farms that are not connected to mains water in countries, such as Australia, New Zealand, and Argentina as well as Hungary and Serbia. These regions too all have documented arsenic levels above WHO safety margins.