Abstract: An article of manufacture and method for holding and treating water contaminated with one or more water-soluble contaminants to substantially prevent the contaminants from seeping into ground water supplies disposed below a water holding area. The article of manufacture and method include the use of a water-holding material, e.g, a water-swellable clay, such as bentonite, for reducing the permeation of the contaminated water into the soil, and an inground treatment layer containing a material capable of adsorbing, absorbing, ion-exchanging, neturalizing or reacting with one or more water-soluble contaminants within the water for removing a substantial portion of the contaminants from the water so that the portion of the held water that permeates the water-holding layer, will be rendered substantially less contaminated.