The complaints that have been made against chlorinated water since the practice was commenced have been very diversified in character and can be numbered by the legion and although some have been justifiable, the great majority has been unsubstantiated and must be ascribed to auto-suggestion.

Almost every one who has had charge of chlorination plants has noted the latter phenomenon, for in some instances complaints have been made following the publication of the information that chlorination was to be commenced but antecedent to its actual operation, and in others when for some reason or another, the chlorination plant has been temporarily stopped. Similar observations have been made in laboratory experiments when independent observers have been requested to detect the chlorinated waters from an equal number of treated and untreated waters. Such observers are wrong in the majority of the waters which they designate as treated ones if the dosage is not in excess of that required for satisfactory purification.

One amusing example of auto-suggestion was experienced by the author some years ago. During a ceremonial visit to the waterworks, the Mayor and several civic representatives happened to visit a hypochlorite plant that was built on a pier over the river and which had no ostensible connection with the city mains. One of the party expressed a desire for a drink of good river water without any hypochlorite in it and was served with water from the plant supply by an assistant engineer of the waterworks department. The water was consumed by all with great relish and as it was being finished, the writer entered the plant and was invited to join them in the enjoyment of this “dopeless” water; on asking where it had been obtained he was astonished to hear that it was from a tap which was supplied with the ordinary chlorinated water of the city.

On many occasions, complaints are justifiable and should be carefully investigated instead of, as is often the case, being attributed to auto-suggestion. The time and energy that are often devoted to endeavouring to persuade water consumers that their complaints are without foundation, can better be utilised in so improving the chlorination process as to eliminate tastes and odours. All complaints should be carefully investigated and a record kept for future reference, for the cause, although not manifest at the time, may be discovered later. The records then provide valuable corroborative evidence.

The nature of the complaints against chlorinated water is very diversified and includes imparting foreign tastes and odours, causing colic, killing fish and birds, the extraction of abnormal amounts of tannin from tea, the destruction of plants and flowers, the corrosion of water pipes, and that horses and other animals refuse to drink it.Tastes and Odours. When an excess of hypochlorite or liquid chlorine is added to a water it imparts a sharp pungent odour and acid taste, characteristic of chlorine, that render it offensive to the nose and palate. In some instances the presence of chlorine compounds is not obtrusive when the temperature of the water is low but becomes so when the temperature is raised. It is especially observable when the faucets of hot water services are first opened and the chlorine is carried off as a vapour by the other gases liberated by the reduction in pressure. For this reason the complaints regarding hot water are relatively more numerous and sometimes constitute the whole of the complaints. In cold water containing appreciable quantities of mineral salts the hypochlorites and hypochlorous acid might not be entirely dissociated; they may become more hydrolysed with an increase in temperature and finally broken down under the influence of the carbonic acid liberated from the bicarbonates by heat.

Chlorine also forms chlorinated organic compounds by action on the organic matter present in water and some of the objectionable tastes and odours of chlorinated waters have been attributed to this agency. Some observers have stated that chloramines were amongst the chloro-organo compounds produced but the author’s experience with the Ottawa supply has demonstrated that simple chloramine (NH2Cl) can be successfully employed for water treatment without causing complaints. It was suggested on page 28 that some of the higher chloro-amines might be the cause of some complaints but at present there is no definite information regarding the formation of these compounds in water and all such hypotheses are little more than conjectures. Letton[1] has reported that at Trenton, in 1911, when the water of the Delaware River was first treated, the dosage was as high as 1.2 p.p.m. of available chlorine and although chemical tests showed the absence of free chlorine, the water had an extremely disagreeable taste which was especially noticeable in the hot water. The conclusion was reached that “the taste and odour were not those of chlorine, but were due to some complex chemical change brought about by the action of the chlorine on the organic matter present in the water.”

The waters that require the most accurate adjustment of chlorine dosage, if complaints are to be avoided, are those containing very small amounts of organic matter. The margin between the dosage required for the attainment of a satisfactory degree of bacteriological purity and that which may cause complaints is usually very small, often less than 25 per cent, with the waters of the Great Lakes and many filter effluents. On the other hand, coloured waters containing large amounts of organic matter can be treated with an excess of chlorine without causing tastes and odours. The author found that the addition of 1.5 p.p.m. of available chlorine to the Ottawa River water did not cause complaints although only 0.8 to 0.9 p.p.m. were usually required for satisfactory purification. Harrington of Montreal has had a similar experience with this water.

The presence of traces of foreign substances in water sometimes produces chlorinated derivatives having repugnant tastes and odours. Creosote and tar oils have caused an odour somewhat resembling that of iodoform and industrial wastes have also produced complaints.

The substitution of chlorine gas (liquid chlorine) for bleach solutions has apparently eliminated tastes and odours in some cases but this may be due to a more perfect control over the dosage rather than to any property of the bleach per se.In some instances the sludge from bleach plants has caused complaints by producing an excessive concentration of chlorine during the period of its discharge. This occurred in Ottawa on several occasions before it was discovered and corrected. When the sludge in the storage tanks reached the discharge valve it was customary to wash out the tank and discharge the sludge into the river. The operators opened the wash out valves to the full extent and the sludge and liquor were discharged into the river about 70 feet away from the inlet to the sedimentation basin and on the downstream side of it. A portion of the hypochlorite was almost invariably carried into the basin and increased the dosage. This condition was remedied by carrying the sludge drain farther down stream and insisting upon the sludge being discharged at a slower rate.

Kienle[2] has reported similar occurrences at Chicago. The hypochlorite was applied at the intake cribs situated a considerable distance off shore. The direction of the wind often necessitated holding the sludge for a considerable length of time but occasionally it was found impossible to await favourable conditions with the result that the wind and wave action carried a portion of the sludge back into the crib and down into the shaft and tunnel.

The temperature of the water at the time of treatment is another factor bearing on the production of tastes and odours. When the temperature is low, water absorbs relatively less chlorine (vide Diagram No. II, page 38) in the same period of time with the consequence that, if the dosage is kept constant, more chlorine is present in the free condition. At Milwaukee (Kienle)[2] with a dosage of 0.24 p.p.m. of available chlorine (as bleach) no complaints were received during the spring, summer, and autumn seasons but when the temperature reached 40° F., they were compelled to reduce the chlorine to 0.12 p.p.m. in order to prevent objectionable tastes and odours in the tap waters.

Abnormal conditions such as freshets, and storms, sometimes cause complaints regarding tastes and odours. Adams[3] found that the complaints in Toronto usually accompanied a change in the direction of the wind, a sustained east wind being the one most productive of trouble. The exact cause for this could not be ascertained but it was usually found that there was an accompanying increase in the number of microscopical organisms (plankton) present in the raw water.

Freshets usually increase the bacterial contamination and necessitate an increased dosage which may cause complaints.

Complaints as to tastes and odours can be best avoided by ensuring regularity of dosage, perfect admixture, and storage of the treated water for a reasonable period. These factors are discussed in detail elsewhere.Colic. Although claims have been made that the consumption of chlorinated water has produced “colic” no corroborative evidence has been adduced and the symptoms have probably been due to some other cause. Dilute solutions of chlorine have been used as intestinal antiseptics in the treatment of typhoid fever without producing irritation of the mucous lining and the usual dose for this treatment is one grain of chlorine. Before taking a medicinal dose of chlorine 140 gallons of water containing 0.1 p.p.m. would have to be consumed, a quantity greater than is ordinarily drunk in a year.

Chlorine and hypochlorites are destructive and irritant to skin and it is possible that hot chlorinated water has, in some instances, a similar effect.

It is inconceivable that the addition of minute traces of bleach or chlorine to water should cause it to extract abnormal amounts of tannin from tea but it is possible that free chlorine, when present, acts upon the tea extractives and produces compounds having obnoxious tastes and odours. Tannin to the ordinary tea drinker represents the disagreeable portion of the tea and an obnoxious taste in tea brewed with chlorinated water would consequently be ascribed to the extraction of abnormal quantities of tannin.Almost all waterworks departments using chlorination have received complaints to the effect that the water had killed fish and small birds. There is usually no evidence that the loss was due to chlorinated water but it is generally impossible to convince the owners that the process of water treatment was not the cause. Many continuous physiological tests have been made of the effect of chlorinated water on small fish and have shown that the concentration used in water treatment is without effect. The author kept a tank of minnows in one of the pumping stations for months without loss although the tank was continuously supplied with water that had been treated but a few seconds previously. The bleach solution was discharged into the suction of the pumps and the water for the fish test was taken from the discharge header.It has been found on many occasions that fish are extremely susceptible to chlorine and hypochlorites. This knowledge has been sometimes used for such nefarious purposes as fish poaching, a few pounds of bleach in a small stream being a simple and most effective method of killing all the fish which are then carried down stream into a convenient net. Chlorinated sewage effluents have also been known to destroy the fish life of the stream into which they were discharged.

The opinion of fish culturists as to the action of chlorinated waters upon fish eggs in hatcheries is almost unanimously to the effect that it is a destructive one. Fish eggs are extremely sensitive to chlorine and hypochlorous acid and very few will survive in a water containing 0.1 p.p.m. of free chlorine. The Department of Fisheries of the Dominion of Canada has informed the author that free chlorine in the water had a marked adverse effect on the hatching of the eggs of Atlantic salmon, Great Lake trout, pickerel, and whitefish, but no effect was noticed when free chlorine was absent. The Department has, however, decided to remove all the hatcheries to localities where water that does not require chlorination can be obtained.The effect of chlorinated water upon seeds, plants, and flowers has been investigated by the Dominion Department of Agriculture and Dr. Gussow (Dominion Botanist) and Dr. Shutt (Agricultural Chemist) who were in charge of the work, have reported that water treated with hypochlorite caused no apparent injury to carnations and hybrid roses. Six varieties of wheat seed, after soaking in freshly prepared hypochlorite solutions (0.05 to 10 parts per million of available chlorine) were all sown on the same day. Germination was found to be uniform throughout and no effect of the chlorine was observed either as regards the rate of germination or the development of the young plants. Experiments on barley and oats produced similar results. Radishes, turnips, cucumbers, and beans also showed no retardation in development after treatment with chlorinated water.

These experiments were conducted with solutions of bleach in distilled water, but identical results were obtained in a later series when the treated city supply (Ottawa) was used.

The results proved conclusively that statements alleging damage to plants, flowers, and seeds by the hypochlorite treatment of water are unfounded and do not merit the slightest consideration.Corrosion of Pipes. Chlorinated water, it has been alleged on many occasions, causes rapid corrosion of galvanised iron water services and especially of the water tubes of boilers, water heaters, etc. When bleach is used for water treatment, a slight increase in the hardness is produced but as this is mostly due to calcium chloride, there is no corresponding increase in the salts that form a protective coating. The presence of traces of calcium chloride and chloro-organic compounds might tend to increase the corrosive properties of a water but this increase is probably so small as to be negligible.

If pipe corrosion is considered by the carbonic acid hypothesis, the use of bleach should tend to reduce it because bleach contains an excess of base that combines with a portion of the free carbonic acid. The results of routine tests for free carbonic acid made on the raw and treated waters at Ottawa are as follows:

These figures shown that the hypochlorite treatment produced a small but definite decrease in the carbonic acid content and should, cÆteris paribus, tend to reduce and not increase corrosion.

If the corrosion of pipes is considered according to the electrolytic theory, a slight increase, due to an increased electrical conductivity, might be anticipated. The effect of the addition of hypochlorite upon the electrical conductivity of distilled water and the Ottawa River water is shown in Diagram VI.

With the concentrations of hypochlorite ordinarily used in water treatment it is inconceivable that the slight increase in the electrical conductivity has any practical significance at low temperatures. The conductivity increases rapidly, however, with increase of temperature and any increment due to chlorination might produce a slight appreciable effect at temperatures approaching the boiling-point of water.

Liquid chlorine does not increase the conductivity to the same extent as an equivalent quantity of hypochlorite but it increases the carbonic acid content in proportion to the dosage used.

The author investigated the action of hypochlorite on galvanised pipes in 1914 and was unable to detect any definite corrosion with normal concentrations of chlorine. The experiments were made with 2-inch pipes and an examination of the first consignment received showed that, although the galvanising on the outside was perfect, the inner coat was very inferior: in some parts there was an excess of zinc that broke away on scraping whilst in others the iron pipe was bare.

A committee of the Pittsburg Board of Trade, appointed to investigate complaints as to pipe corrosion, reported in 1917 that they were largely due to inferior qualities of pipes and not to the method of water purification employed (slow sand filtration and chlorination).

The effect of chlorination on the plumbo-solvency of water was investigated in 1904 by Houston who found that chlorine, as chloros, in amounts between one and ten parts per million, did not appreciably increase the plumbo-solvent action of either unfiltered or filtered water. Similar results were obtained by the author with the Toronto supply: raw lake water, filtered water, and water treated with 0.25 and 0.50 p.p.m. of chlorine, all dissolved the same quantity of lead in twenty-four hours. The amount in each case was too small to be of any significance.

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