History of the Water Supply of the World / arranged in a comprehensive form from eminent authorities, containing a description of the various methods of water supply, pollution and purification of waters, and sanitary effects, with analyses of potable waters, also geology and water strata of Hamilton county, Ohio, statistics of the Ohio river, proposed water supply of Cincinnati.

by Thomas J. Bell

AERATION

is the destruction of animate life by oxidation, and is best accomplished by placing weirs across streams, sheet flashing, or spreading of water in thin sheets, or by roughness of beds or banks of running waters. The benefits may be ascertained, chemically, by the presence of nitrates and nitrites. The Water Supply Commission of Engineers, for the investigation of the water system of Philadelphia, say:

“This is one of nature’s processes for purifying water, not only of the land, but of the ocean, and bodies of water deprived of it, other processes are apt to set in. It is, therefore, desirable that nothing should be done to obstruct this beneficial action. We have been informed that the cutting of ice, which was formerly allowed on the Fairmount pool, has been prohibited or discontinued. We would especially recommend that the cutting of ice on the pool be resumed, as an important sanitary measure, on account of the aeration it will afford. If this were done systematically, it might remedy, at least to some extent, the disagreeable odor which we learn is sometimes noticed during the winter.”

The aeration adopted by Mr. Moore, Supt. of Cincinnati Water Works, at Eden reservoir, improved the purity of the water twenty per cent., as shown by the analysis of Prof. Stuntz, who recommends the adoption of the process on a larger scale.

Covered Reservoirs, although used by the ancients, are now being recommended as highly beneficial to the purity of the water, by depriving the organic germs of their propagation elements of light and heat of the sun, preventing freezing of water, and reducing evaporation to a minimum. Paris has two such structures. Chelsea (London) Water-Works has one of ten million capacity that cost $110,000.00.

The temporary hardness of water is produced by absorption of carbonates, and may be reduced to softness by:

Distillation,		Boiling,
Carbonate of soda,		Caustic lime.

Permanent hardness is produced by sulphates, chlorides and nitrates of lime, and magnesia, and can not be dissipated by boiling.

An imperial gallon of pure water can take up but about two grains of carbonate of lime, but the presence of carbonic acid in the water will enable the same 70,000 grains (an imperial gallon) to take up twelve, sixteen, twenty, or more grains of the carbonate, and for each grain so taken up is one degree of hardness by the Clarke scale.

The system patented by Dr. Clarke, of England, in 1856, is the most practical method for the precipitation of lime, effected by means of a dilution of water with slaked lime, in the proportion of one of lime-water to ten of hard water. The system is in use in several small places in England, notably Canterbury, where 100,000 gallons are reduced, daily, at a cost of twenty-seven shillings per million gallons, with the following results:

	TOTAL SOLID IMPURITIES.	ORGANIC CARBON.	ORGANIC NITROGEN.	HARDNESS.
Before,	33.60	.012	.012	26.3
After,	11.94	.0	.0	4.9

Plumstead water-works, previous to its purchase by the Kent Water Company, of London, reduced, daily, 1,000,000 gallons by the Clarke method. The new owners, however, abandoned it.

From the testimony of a number of reputable physicians, before the Rivers Pollution Commission, of 1874, hard water, to a limited extent, ten degrees, was not considered injurious, and, by some, absolutely beneficial to health, although soft water, for a general water supply, was preferable.

Mr. Homersham, C. E., the designer of several of these works, testified, before this commission, that it cost £1, 7s. for precipitating 1,000,000 gallons. To introduce this system into London, with a consumption of 100,000,000 daily, the cost, he says, would be $3,000,000 for plant, and requiring over thirty-three acres of ground for basins, etc.

The relative sanitary condition of cities, in the United Kingdom, using hard and soft water, is shown in the following table:

NO. OF TOWNS.	AVERAGE POPULATION.	CHARACTER OF WATER.	AVERAGE RATE OF MORTALITY PER 10,000.
26	73,366	Not exceeding 5°	29.1
25	81,655	Above 5°, but not exceeding 10°	28.3
60	44,797	Above 10°	24.3
London	3,254,260	From 16° to 32°	24.6

The celebrated engineer, Mr. Bateman, of England, estimates the saving to Glasgow, by soft water, at $180,000 per annum; and if London used the same character of water, the equivalent would be $2,000,000 annually.

The use of lime, by private consumers, is recommended by the trustees of the water department of Columbus, O. They say that one ounce of lime, when added to thirty-six gallons of water, make it superior, for washing purposes, to the rain-water usually obtained from the cistern.

CHAPTER IV.
SYSTEM OF SUPPLY.

The systems of supply may be arranged under three general heads, viz:

1st.	By springs and wells.
2d.	By gravitation.
3d.	By pumping.