Q. What should be the dimensions of the flush-tank and settling-basin for disposing of the sewage of a hospital of twenty-five beds by subsurface irrigation?

A. We should make each about five feet diameter and five feet deep below the water-line, or of equivalent capacity; broader and less deep if more convenient. The storage would then amount to about 750 gallons. There would be needed from 2,000 to 2,500 feet of distributing tiles, depending on the porosity of the soil, the more porous soils needing less pipe than clayey soils. The above is based on the supposition of an abundant water-supply under constant pressure. If water is to be supplied by hand-pumping, half of the above capacity would be ample.