Many conclude that wooden or iron reservoirs, or those that are walled and cemented, can alone be depended upon. But over the world the fact has been long known that on quite firm soil the banks and bottom, if well puddled, will hold water quite as well as the cemented reservoirs and give less trouble, as the frosts of winter do not injure the earth banks, but often do much damage to cement-work. In Kansas and Nebraska they have had the most favorable experience with reservoirs excavated even in rather light soils.

Mr. A. S. Perry, of Frisco, Oklahoma, after long experience says: "These ponds are made to hold like jugs -except from evaporation - by puddling one hour a day for two weeks. This is done by using a drag to stir the mud made by some water pumped in. Stirring the mud keeps it muddy and the sediment stops the pores of the soil, which soon becomes impervious to water and seepage. This will work on any clay soil or on a clay loam with some sand."