FOR A PURE WATER SUPPLY.
According to the opinion of the Local Government Board of England, there is no river in the British Islands long enough to allow of the oxidisation of sewage matter that has been discharged into it. Hence, the extreme care shown in that country to secure either a pure source of water supply, or, at least, furnish filtered water to the consumers in its large towns and villages. The freezing of lakes and rivers neither purifies the water nor kills the bacilli, as is shown at Edmonton. Sask., where from the Saskatchewan river above Fort Saskatchewan can be taken from below several feet of ice the solid sewage of that city which has been discharged into the stream in liquid or semi-liquid shape twenty-five miles above. This practice, as in many other examples of a like kind, sets at naught the old common law principle that ‘‘no man has the right to injure his neighbor.” In’these days, of course, it is next to impossible to bring it about that rivers, lakes, small creeks and streams in the neighborhood of a city or manufacturing or mining village shall not be contaminated either bv sewage or poisonous discharges from mills or mines, for which reason filtration has to be resorted to, unless, indeed (as the Canadian Municipal Journal points out, and has been shown times out of number in the columns of FIRE AND WATER ENGINEERING) the water can be taken from a natural reservoir, or an artificial reservoir can be constructed at the bottom of a valley and all the water as it comes down from the neighboring hills impounded, or the head-waters of a river can be .captured and stored in a reservoir, or an unnavigable river can be dammed. This catchment-area source of supply is the most safe and satisfactory Of all; but those who arrange to get water in’this way should obtain such a control over the catchment-area as to be able to absolutely prevent the erection of dwellings thereon. This is important by reason of the fact that, should excreta from a person suffering from typhoid fever be emptied on a catchment-area, an epidemic amongst the water consumers is almost sure to follow. In Belfast, Ireland, both the old and the new systems are on this principle; but some years ago the catchmentarea of the old system contained dwellings and farms. The farmers when they came to the city, used to buy and eat shellfish gathered in certain seasons on the shores of the Belfast lough, which is an arm of the sea. wherein at that time the sewage of the city and other smaller towns was discharged in a raw state. Some of these farmers, after eating the shellfish, would become ill with typhoid, and it was noticed that, when such a case occurred on the catchment-area, after a short time an outbreak of typhoid in the city itself would take place. This compelled the commissioners to purchase outright and remove from .off the catchment-area all the dwellings, etc., thus converting the area of cultivation into a wilderness. with the result that the number of cases of typhoid was materially reduced. The new system for Belfast, when fully completed, will cost $“,•• 500,000 to obtain a supply of 33,000,000 gals, per day from the Mourne mountains. Birmingham has recently spent close on $35,000,000 to obtain a supply of 60,000,000 gals, per day from Elan valley, Wales. Edinburgh recently spent about $7,500,000 on the Falla scheme, to obtain a supply of 20,000,000 gals, per day. Glasgow obtains its supply from loch Katrine; Liverpool, from lake Vvrnwry in North Wales. Ottawa, Ont., is likely in the near future to take its supply from a mountain lake some fifteen miles away, instead of from the river. 1 his method is also the one most frequently encountered in American practice. It is the simplest; it admits of the greatest amount of certainty in determining the quantity and quality of the water and the kind and cost of the work necessary to utilise the supply. It may not be possible for some of the prairie towns of Alberta, one of the newest provinces of the Dominion of Canada, to obtain their supply from catchment-areas; but, amongst the other towns where such can possibly be done, this source, even though it is costly in the first instance, will prove in the long run the least expensive, and is ccrtainlv the safest and most satisfactory. Where filtration is resorted to, and it is dailv becoming more necessary and more common, the mechanical filter is coming into geheral use, although many cities are preferably adopting the slow-sand system. Aeration and filtration combined form a highly desirable method of purification, which is being used in several places. At Charleston, S. C., an aeration and mechanical filtration plant has recently been installed. One system embracing the three, sedimentation, aeration and filtration, is excellent. Along rivers, deep, narrow coulees can sometimes be found w’here dams could be constructed to form cheaply large sedimentation reservoirs; to these could be added aeration and mechanical filtration plants. The water of the river could be pumped to the sedimentation reservoirs. where, after remaining for some time, it could be passed on to the aeration and filtration plant, thence to the pump wells, from which it can be pumped to the standpipe for distribution; or, sedimentation reservoirs can be situated on low lands near the river where water can be allowed to enter by a sluice. Local circumstances, however, in this, as in other schemes, would decide the matter.