The wisest plan before deciding on a brook supply is to measure the volume of water which flows in the brook at the time when it is lowest, probably about the middle of August. The actual volume of water needed for the household is not large, although its required rate of flow may be high and, as already pointed out, a stream which furnishes water at the rate of one quart in five minutes is sufficient for a family of three persons, a rate which is almost a drop-by-drop supply. Such a stream would require a reservoir somewhere in order to supply the faucets at the proper rate, and for a single family a small cistern or even a barrel sunk in the ground would be sufficient for this purpose. An objection to the utilization of so small a flow in connection with the smaller storage is that the temperature of the water in summer is so raised that vegetation and animal growths take place easily and freely, so that the taste and smell of such water is most disagreeable. These consequences can be avoided even with the low flow by increasing the storage, since the larger quantity of water has been found to resist the bad effects of the low flow and high temperature. Figure 35 shows a small reservoir actually in use to supply water for a single house. [Illustration: FIG. 35.--A reservoir for home use.] _Storage reservoirs._ But even if the stream actually dries up for two or three months, it is still possible to use it for water-supply, provided a suitable location for a dam and pond can be found where storage, as described in the preceding chapter, can be secured. For this reason as well as for the greater benefit to the quality of the water, brooks flowing through rough, wooded, and uninhabited country are to be preferred as a source of water-supply to brooks flowing through flat agricultural land, and in many cases, where their flow is largely due to springs, the brooks themselves may compare favorably with springs in quality. _Ponds or lakes._ Water may be properly taken from ponds or lakes whenever the danger from pollution is negligible. No better source of supply can be imagined than a pond in the midst of woods, far away from human habitation, presumably furnishing an unlimited supply of pure soft water. Sometimes water from such ponds contains large amounts of vegetable matter, the result of decomposition of swampy or peaty material, as, for instance, from the ponds in the Dismal Swamp of Virginia, so that the water has a yellow, coffee-colored appearance. The appearance of such water is suspicious, but it need not be feared unless something more pernicious than the coloring matter is present.