Pittsburgh obtains its supply from the Alle gheny River, which has several inflowing tribu taries. One of these is the Kiskiminetas which receives waste products from oil refineries, tan neries and other plants. The water carries much colloidal matter. Its waterworks plant com prises concrete sedimentation basins, holding 120,000,000 gallons with 24 roughing filters of coarse stone and two hollow frame baffles, ex tending the full length of the sedimentation basins. These rid the water of much of the matter in suspension. It also comprises slow sand filters and a covered filtered water reser voir. The plant is unique and illustrates an other type of construction to overcome condi tions quite extraordinary. Its service reservoir is at Highland Park 367 feet above the river. It has several reservoirs for service in different parts of the city.
Los Angeles formerly obtained its supply from ground waters by means of infiltration galleries. Its daily consumption was 26,000,000 gallons. It is soon to obtain its supply from Owens Valley where the city owns a large catchment area. Long Valley and Tincmaha reservoirs are to be constructed with a com bined capacity of 150,500,000.000 gallons. The aqueduct consists of open canal sections, ma sonry sections and tunnels and several inter cepting reservoirs, each of many million gallons capacity which regulate the flow and develop power. It is so constructed that ground water near the surface may be pumped into it and ent its volume. It has 23 inverted siphons an serves both for water supply and power purposes and is one of the large water supply projects on the Pacific Coast.
San Diego has a municipal pressure filter of 5,000,000 gallons capacity.
San Francisco is supplied by five independent systems owned by a private corporation. The waters are drawn from artesian wells.
In June 1919, Sacramento decided to install a modern filtration and pumping plant with fil ter beds of 30.000.000 gallons daily capacity and is to use sulphate.of aluminum as a coagulant Its water supply is from riser water, mountain sources and from wells.
In addition to those already mentioned, puri fication plants have been constructed at Wil mington, Cincinnati, Cleveland, Columbus, To ledo, Lorain, Youngstown, Louisville, Saint Louis, Des Moines, Minneapolis, Grand Rapids, Mich., Little Falls, N. J., Harrisburg and fected by chlorination and an electrolyser of the Allen-Moore cell adopted by the Montreal Water and Power Company. The equipment comprises four cells, each having a capacity of Bethlehem, Pa., Middleboro, Mass., and at many other places in the United States and other countries.
The water supply in Canada is illustrated in the following few cases: The Victoria aqueduct conveys waters from mountain reservoirs 37 miles away.
At the present time Winnipeg obtains waters that require softening and that involves large expense annually. It has recently decided to obtain soft water from Shoal Lake, some dis tance away.
Toronto obtains its supply from Lake On tario. Its filter beds of its slow sand system have a capacity of 5,000,000 gallons per acre per day. It has recently installed drifting sand fil ters. These consist of 10 units, each having a capacity of 6,000,000 gallons daily. In them there is a constant vertical circulation of water through the filters, so that a part of the bed of sand is kept in suspension in the water, while some of the sand is being constantly re moved and washed in transit and replaced in fibers. A coagulant apparatus is attached and the coagulant goes directly to the filters. The bacteria are caught up and carried along out with the drifting sand. The process is rapid and may be expensive. The average amount of chlorine applied was 2 parts per million in 1918. In 1911 Toronto daily consumed 118, 09,000 gallons.
Montreal obtains its supply from the Saint Lawrence and Ottawa rivers. The waters are conducted into the main reservoir 200 feet above the Saint Lawrence River. That reservoir has a capacity of 36,500,000 gallons. There is an other high service reservoir still higher. Puri fication of the water supply of Montreal is ef 32 pounds of chlorine per day. The process has been credited with 93 per cent efficiency. In 1914 Montreal supplied an amount equivalent to 153 gallons for each of its 600,000 inhab itants.
The republics of South America are likewise appreciating the necessity of providing pure water for their inhabitants. In 1867-68, there was an epidemic of cholera in Buenos Aires, Argentina, which had 1,500 victims, and in 1871 yellow fever followed, which had 2,600 victims, both due to unsanitary water supply. Aroused by this condition the city employed eminent engi neers and constructed a system of modern waterworks. The city obtains its water from the Estuary at Belgrano. It is then conducted three and one-half miles to Recoleta, where there are settling basins of 12,000,000 gallons capacity and six acres of covered filters. The filtered water is then pumped to great distrib may understand what is involved in obtaining such supplies and the menace to health and to life in drinking impure water.