CHAPTER VI Tue BurtpInc—Its WATER SUPPLY (Part 1)

CHAPTER VI Tue BurtpInc—Its WATER SUPPLY Composition of Water. Water is a chemical compound of hydro- gen and oxygen, each molecule consisting of two atoms of the former to one of the latter; by weight it consists approximately of oxygen 89 per cent. and hydrogen 11 per cent. As found in nature, it is almost impossible to obtain water free from impurities, which take the following forms: dissolved and suspended inorganic and organic matters, and micro-organisms. Impurities. The amount of dissolved inorganic matter in a sample of water depends very largely on the nature of the soil, through or over which it has passed. The chief mineral impurities are lime salts, chiefly the bicarbonates and sulphates; others are bicarbonate and sulphate of magnesium, chloride of sodium, iron salts, and silica. The salts of metals are also found, chiefly those of lead and copper, the first named being poisonous and the more common. The presence of lead in water is generally due to its being taken up by acid water, or water containing a large amount of nitrates and no bicarbonates, in passing through lead pipes or when stored in lead-lined cisterns. Water containing the smallest quantity of lead is dangerous for domestic purposes, as its effect is cumulative, so small a proportion as 1 part in 700,000, or 0-1 grain per gallon, being suflicient to set up lead poisoning in the system of a person who is in such a state as to be readily affected. The hardness of water is due to salts of lime and magnesium, but a moderate hardness is not harmful. Suspended Inorganic Matter. The suspended inorganic matters are chiefly brought into the water in the form of impurities washed from the air by rain, or taken up in its passage over or through the soil. Examples are minute particles of sand, chalk, marl, oxide of iron, ete., all of which will settle and form a sediment when the water is at rest. They frequently cause colour but are not neces- sarily harmful to it, and are easily removed by filtration. Dissolved Organic Matter. Dissolved organic matters may be of either vegetable or animal origin. The former are not neces- sarily harmful, but the latter, consisting of ammonia compounds and matters arising from putrefaction, are always dangerous. Thus water from a peaty soil may be wholesome, but the presence THE BUILDING—ITS WATER SUPPLY 157 of animal organic matter often indicates sewage pollution, and any water containing traces of it should be rejected, unless it can be suitably treated. Suspended Organic Matter. Water containing suspended organic matter is also always suspicious, as it may be accompanied by the presence of disease germs. Examples of suspended vegetable organic matter are woody fibre, pollen, starch cells, and fungi, and of animal matter, hairs, dead insects and other minute animals, and possibly scales from the skin of diseased persons, Micro-Organisms. Micro-organisms may be of either a harmful or a hurtful type. They are so minute that their classification is a matter of difficulty, but it is known that polluted waters abound in germ life, and therefore the greater the number of bacteria pre- sent, the more suspicious the water is. Quality of Water. A good water for domestic purposes should fulfil the following conditions: It should be practically colourless and clear, free from sediment, and sparkling and pleasant to the taste. It should have no smell, be soft to the touch, dissolve soap easily, and be sufficiently aerated. It should be free from organic pollution and contain no more than a small number of bacteria. Simple Tests of Water. Some of these requirements can easily be verified by simple tests; others by experts only. The rough tests which can be applied by almost anyone will first be described. Palatibility. Palatibility is purely a matter of tasting. Smell is also a matter for the senses, but one must go further. Take a stoppered glass bottle of large size, such as that known as the “Winchester quart”, and holding about half a gallon. Wash it out with a weak solution of sulphuric or hydrochloric acid and rinse it out repeatedly with the water to be tested. Immerse the bottle in the water, allow it to fill to within about 2 inches of the neck and securely stopper it. Expose it to light and warmth for not Jess than twenty-four hours, to see if vegetation is set up or putrefaction occurs. On removing the stopper, this will be discernible by smell, and water not bearing this test should be rejected or suitably treated. Colour. If water is tinged with colour, it is generally due to dissolved organic matter, such as peat or decayed leaves, though it may be due to iron, in which case it is not necessarily a bad water, although one to be avoided if possible. The colour cannot as a rule be judged merely from filling a tumbler. We should use two glass tubes, each about 24 inches high and 2 inches in diameter. One should be filled with distilled water and the other with the water to be examined. If they are placed on a white tile or sheet 158 THE BUILDING—ITS WATER SUPPLY of white paper, a comparison of colour can easily be made, when viewed from above and the tube lifted about 2 inches from the tile. If found to be tinged with colour, a rough test can be made in order to see if the cause is organic matter. Add a drop of Condy’s fluid to a glass of the water, which should thereby be turned pink. If the pink colour remains, all is well as regards this point, but if the colour be bleached, the presence of organic pollu- tion is indicated. The presence of chlorine (as chlorides) may be detected by adding a small quantity of nitrate of silver and dilute nitrie acid, Small tabloids are obtainable for this purpose. If chlorides are present, the fact will be indicated by a haziness or bya more or less white precipitate, 1 grain per gallon giving a haziness, and as much as 10 grains per gallon a considerable precipitate. The presence of chlorides in considerable quantities is not sufficient in itself to cause one to condemn a water. It may be due to urine or other such animal contamination, or it may be due to the water having passed through or over rocks containing chlorides; it may also be due to sea-spray or to seaweed used as manure. The cause of its presence should therefore be investigated as far as possible and perhaps a geologist consulted. If the above rough tests clearly indicate serious pollution the source of supply might as well be abandoned at once, if any other source is available; otherwise it would be necessary to install expensive filtration and sterilisation apparatus, as will be explained later, Analytical and Biological Tests. Lf the water passes these rough tests satisfactorily, it should be submitted to expert investigation by an analytical chemist and preferably by a bacteriologist also. The manner of taking the sample for an analyst is important. It should be of sufficient quantity and accompanied by the fullest particulars. A ‘‘ Winchester quart” bottle should be obtained, and cleaned and rinsed out as before described. It should be filled to the neck, the stopper being firmly put in and covered by a strip of leather or cloth, Shih should be tied round and sealed. If a glass stopper is unobtainable, a cork may be used, but it must be a clean, new one. The bottle should be labelled with brief par- ticulars and the date, and at once forwarded to the analyst with the fullest particulars, such as the nature of the source and reason for requiring the analysis. For example, if it is a case of illness, the nature of such illness. In the case of a supply from a well, the approximate depth, position in relation to drains and cesspools, if any, and any other possible source of pollution should be stated. The analysis should be commenced within forty-eight hours if THE BUILDING—ITS WATER SUPPLY 159 possible. Water supplies require examination from time to time. Occasional pollution may be due to a spell of heavy rainfall, bad condition of filters, or in the case of a house, defective cisterns and fittings. Taking Samples. For the bacteriologist a smaller bottle is used, generally of about 8 to 12 oz. in capacity, fitted accurately with a ground glass stopper. This should be thoroughly sterilised before use. The stoppered bottle should finally be made secure by a piece of oiled silk tied over the stopper. It is also necessary that it should be kept very cold and examined with the least possible delay. Bacteriologists use special bottle cases for the transmission of samples. The bottle fits into a tin-lined recept- acle, surrounded by another casing for holding ice, this in turn being surrounded by a layer of asbestos, and the whole fitting into a wooden box fitted with a lock. If the sample is to be drawn from a pump or tap, the nozzle of the pump or tap must be thoroughly cleansed, and then flamed with a plumber’s blow-lamp, or else wiped with a large wad of cotton wool, soaked in methylated spirit. Reading the Analytical Chemist’s Report. The report of the chemist is sometimes rather too full of technicalities to be readily understood by the surveyor, but there are certain guiding points which may with advantage be referred to. A large quantity of “albuminoid”’ ammonia, together with large amounts of “free” ammonia and chloride, points to sewage pollution. This will be confirmed if the bacteriologist finds large quantities of those bacteria which are characteristic of animal pollution. 1 A large quantity of “‘albuminoid” ammonia, with only a little “free”? ammonia and a little chloride, points to vegetable con- tamination only. This will be confirmed if the bacteriologist finds few of the bacteria which are characteristic of animal pollution, In addition to the ammonias and chlorides, nitrites and nitrates may be present. Nitrites and nitrates are always found in sewage effluents after treatment of the sewage in bacteria beds. Nitrites indicate that there has been a quantity of organic matter present, that this has been undergoing oxidation, but that the process is not yet complete. Nitrates indicate that oxidation of such organic matters is complete. If a water contains nitrites and nitrates the report of the bacteriologist will again be of great interest, as the bacteria originally present may still be present in very large uantities. ; The most useful information that can be derived from a chemical 160 THE BUILDING—ITS WATER SUPPLY analysis is from the determination of the quantity of albuminoid ammonia present, and the amount of oxygen which will be ab- sorbed by the water when kept at the standard temperature of 80° Fahr. for the standard time of four hours. Chemists will normally approve a water if it has not more than 1 or 1} parts of albuminoid ammonia in ten million parts of water, and if it will, at the same time, not absorb more than one part of oxygen per million of water. Reading the Bacteriologist’s Report. The report of the bacteri- ologist is of a character even more technical than that of the chem- ist. He is able to distinguish the possible presence of “ patho- genic” (harmful) bacteria in a sample of water, and to estimate the quantity of both the pathogenic and non-pathogenic varieties, and to draw conclusions as to the degree of pollution to which the water has been subjected. The normal procedure in water examination is to look for and count a group of bacteria known as “Bacillus Coli”, an intestinal organism which is to be found in immense quantities in the excretions of all animals, healthy or otherwise, and which is able to survive for long periods in water at ordinary temperatures. The importance of this group lies in the fact that its presence in a sample of water clearly indicates con- tamination from animal excretion and that all the water-borne diseases affecting man, such as cholera, typhoid, para-typhoid, dysentery, ete., are transmitted from the intestines of animals. To search for the specific bacilli of the aforementioned diseases is too difficult an undertaking to be practical in routine water examination, though it might be attempted in special cases, as where a disease has broken out locally. It may be taken as proved fact that a natural water which con- tains no Bacillus Coli cannot contain any dangerous number of any disease-producing bacteria, and that a polluted water which has been so treated as to destroy all Bacillus Coli is as incapable of producing disease as the purest natural water. It is usual to look for Bacillus Coli in samples of 0-1 ¢.c., 1 ¢.c., 10 c.c., 50 c.c. and 100 e.c. If the bacillus is present in 50 c.c. the water is viewed with suspicion; if present in 1 ¢.c. it would be regarded as dangerous. Water Treatment. A water which is found not to comply with the above standards of chemical analysis and bacteriological examination would not necessarily be discarded forthwith; no better water may be available at a reasonable cost. A careful examination of the source of the supply and its surroundings should be made with a view to the removal of sources of pollution, THE BUILDING—ITS WATER SUPPLY 161 after which the water may be tested and examined again. If this proves fruitless, the water, if not hopelessly polluted, may be rendered safe by filtration, accompanied probably by sterilisation, by methods which will be described later. Quantity of Water Consumed. It will be obvious that the quan- tity of water required per head of population per day depends on a variety of circumstances. Thus, in a village, it is often limited to that needed for cooking, drinking, clothes washing and house cleaning, and a small amount for waste. The use of water-closets is less general in villages, earth-closets and privies being used in- stead. Bathrooms, also, are less general, unfortunately, in coun- try cottages, and so there is not a great demand for water on that score. Similarly, there is no question of flushing drains and sewers, nor are there any public conveniences to be automatically flushed, nor manufactories to be supplied with water for conversion into steam or used in trade processes. It would appear reasonable therefore to suggest the following figures: for country cottages without baths or water closets, about 5 gallons per head per day; for a village, about 12 to 15 gallons per head per day; for a resi- dential town, about 20 to 30 gallons; and for a large manufacturing town about 35 to 50 gallons per head per day. The original source of all available water is the rainfall. Part sinks into the ground to form underground supplies, part flows off the surface to form streams, and part evaporates. The amount of rainfall varies greatly in different places; thus on the East coast of England it averages about 20 inches per annum, on the South coast about 30 inches, and in a few places in the Lake District it is over 100 inches per annum. The amount of rainfall is measured by means of rain gauges. Rain Gauges. The sketch, Fig. 133, shows a vertical section through a common form. It is constructed principally of copper, and consists of (1) a cylindrical body; (2) an inlet, fitting into a groove round the top of the body, cylindrical at the top, with a bevelled edge, and in the form of a funnel at the bottom, termin- ating in a tube; (8) a bottle or other similar receptacle; and (4) a separate measuring glass graduated to read inches of rainfall and applicable only to the gauge with which it is supplied. The instrument is secured to the ground with small oak stakes and is fixed with its mouth about a foot above the ground, to prevent water splashing in. It is made of various diameters, but that in most general use has a diameter of 5 inches at the mouth. Rain gauges must be fixed in an open space, clear of any obstructions such as trees or anything likely to prevent the direct access of 6—D.S. THE BUILDING—ITS WATER SUPPLY 162 "PERMEABLE PP ee aah ’ at IMPERMEABLE SURFACE SPRING 134 oT PERMEABLE’ TTT” imPERMEABLE DEEP SEATED SPRING PITTI III TIT IIIT ett aaa ys) , / Mehl” DEEP SEATED SPRING 4 tf! uf / SURFACE SPRIN 779M d790 & 777M MOTTVAS ef Sv: eS 57 heme THE BUILDING ITS WATER SUPPLY 168 rain. In dealing with a large area, a series of gauges would be used, scattered about the district; thus in the huge water supply scheme of the Derwent Valley Water Board, for the supply of Leicester, Derby, Sheffield and Nottingham, the catchment area of which scheme is nearly 50 square miles, fifty rain gauges were used, or approximately one per square mile. This is generally regarded as sufficient to enable one to deduce a sound average. Sources of Water Supply. Let us next consider the sources from which water is obtained, dealing with this point under two headings, (1) geological, and (2) practical. Alluvium often rests on an impervious bottom, on which water will collect, and which can be reached by sinking a well. In some parts of the Pleistocene formation a layer of middle drift is found between two boulder clays, in which case wells sunk through the upper clay will provide a hard water. The Pliocene can be bored in many places for water. In the case of the Oligocene, the sands of the Osborne beds contain hard water, and water is invariably found at the surface of the Barton clay. With the Eocene formation, the Bagshot sands, where they rest on the Bagshot marls, provide a supply for wells. The London clay is impervious, but the Oldhaven, Woolwich and