(For more detailed information see Major Tulloch's Water - Supply of Bombay (1872). Michael's History o' the Municipal Corporation (1902), Clerk, Sadasewjee & Jacob on Impounding Reservoirs in India (1894) ; Santo Crimp's Report on Bombay Water Supply, 1899.)

Like - most eastern cities Bombay was of old the possessor of many tanks and"wells, constructed by pious citizens for the public good, the water of which was used by the inhabitants both for washing their clothes, household utensils and bodies, and also for drinking.(A good example of such tanks was Framji Cowasji tank, bordering the Esplanade, which was built in 1831 by an enterprising parsi for the benefit of residents in the locality. Another was the big tank constructed in 1849 near the Grant Medical College, into which several springs of salt water gushed from the Byculla side. These springs increased and decreased with the spring and neap-tides. (Bombay Times, June 6th, 1849). Others were the Two Tanks in Duncan road, built before 1823, and supplied with water by an aqueduct from the Cowasji Patel tank.) The wells were of an average depth of 30 feet ; and like the tanks were mostly situated in crowded localities and thus peculiarly liable to pollution. The location of a private. well within the house was regarded as a special luxury to be enjoyed only by the rich ; and many houses in the Fort were supplied in this way with water which percolated from the foul ditch surrounding the ramparts. In fact, up to 1860, the conditions of an impure water-supply were abundantly fulfilled by insanitary surroundings, and natural facilities afforded to the drainage of organic impurities into the wells left little room for doubt that liquid sewage formed no insignificant constituent of much of the drinking water.(Tulloch's Water Supply of Bombay (1873), 209-10.)

Nevertheless it was rather the scarcity than the impurity of the water-supply that underlay the efforts to improve it. In 1850, for example, the only water to be found on Malabar and Cumballa hills was situated at Walkeshwar village on the one side and at Tankerville (Gowalia Tank road) on the other, and the total quantity obtainable throughout the island cannot have been much more than one-tenth of the amount now used by the public. Water-famines were by no means uncommon, one of the largest occurring in 1824 and resulting in a public enquiry into the condition of the wells and tanks. But no definite steps towards improvement were taken until 1845, when the deficiency of water in the town forced Government to appoint a committee, composed of Dr. Graham and Dr. Leith, to devise measures for enhancing the supply. Various proposals were put forward, among them being that of Mr. L. C. C. Rivett for impounding the surface drainage of the Neat's Tongue (Trombay), which according to his calculations would have provided the town with 200,000,000 gallons a year at a cost of some 7 lakhs. Colonel George Jervis, on the other hand, believed in the construction of three reservoirs at Dhobi Talao, Girgaum and Mahim, the first of which was to supply the Fort, the second the town proper, and the third Parel, Byculla and Mazagon, the water being pumped from them by steam-power and distributed through pipes to those areas.(Tulloch's A Water-Supply of Bombay (1872) This proposal, however, lost weight from the fact that the existing tanks were often extremely low and had occasionally to be replenished by the sinking of new wells. The old Cowasji P,.tel tank, for example, was very short of water in 1846; and the situation was only saved by Mr. Framji Cowasji, who purchased the Mugbhat oart and sank three large wells in it, from which the tank was supplied by means of steam-machinery at an outlay of Rs. 30,000.
(Michael's History of the Municipal Corporation, pp 68,69.). Mr. Framji Cowasji obtained the Powai Estate vs freehold from Government in 1837 on condition of always keeping the the Two Tanks supplied with reasonable quantity of water.)
A third proposal by Captain Turner to impound water on Malabar hill and Cumballa hill was likewise rejected.

The project finally adopted was the outcome of a report, submitted by Captain Crawford of the Engineers in 1850, in favour of drawing the city's water-supply from the Vehar In 1852 Mr. Conybeare was asked to scrutinise the proposals of his predecessor and by 1855 he had elaborated the great scheme for the construction of the  Vehar lake, in conjunction with a minor scheme for the distribution of rater by iron pipes to nearly all part- of the city. Outlying villages were to be supplied by means of draw-wells kept constantly full by masonry conduits connected directly with the main pipe. The scheme was formulated by no means too soon; for in 1854 so terrible a water-famine occurred that the Great Indian Peninsula railway and country-boats had to be used for the daily transmission of water from the mainland into the town.(The author of the Marathi Mumbaiche Varnan gives a graphic description of the shifts resorted to by the people, in this crisis. Prayers and offerings to the gods were made daily ; an image of one of the sages was mad.., consecrated and worshipped for eight consecutive days ; all cattle were removed from the city to Mahim ; and a single jar of muddy water was in most cases all that the poorer families had to depend on for several days.) Nevertheless a certain amount of trouble was experienced in raising the necessary funds, so that the lake and its ancillary works were not completed till 1858. (The ceremony of turning the first sod of the new works was performed by the Governor-General on January 31st, 1856, in the presence of Lord Elphinstone and a large gathering of Bombay residents. Bombay Times, 2nd February 1856.)
Water was introduced in the year following, the daily supply amounting to roughly 9½ million gallons. This supply proved within a few years wholly insufficient for the needs of a population, which from the commencement of the cotton-boom and share-mania was annually increasing by abnormal strides ; and in 1866 therefore meters were introduced and applied to about 3 p. c. of the total supply, including all Government, factory and public company connections. By 1868 an enhanced supply had become an imperative need ; and on the motion of Dr. Blaney, the Municipal Commissioner was desired to submit proposals for the extension of the supply. Four separate schemes, the Shewla, Kennery, Tulsi and Powai, formed the subject of this report ; and of these the Tulsi scheme, which consisted in damming the river Tasso and diverting its waters into the Vehar lake, ultimately found favour with Mr. A. R. Scoble's commission,. which was appointed by Government in 1869 to discuss the four alternative projects. Plans and estimates were prepared in 1870 ; the works were commenced in 1872 and completed in 1879, together with a settling tank and covered service reservoir on Malabar Hill, which are connected with the Tulsi lake by a 24-inch main( The water from the Tulsi catchment area was actually diverted into Vehar from 1874 onwards, before the completion of the Tulsi works. This saved the city from a serious failure of supply in 1876 and 1877. Administration Report of the Municipal Commissioner for 1877.) The additional supply thus obtained amounted to about 4 ½ million gallons a day. The John Hay Grant or Bhandarwada reservoir with six filter beds for Vehl.r water was also commenced in Mazagon on the 10th May 1880 and the water from Vehar lake was diverted into the reservoir on the 7th April 1884.

Still the city continued to increase rapidly in size, and by 1884 the yield of Tulsi and Vehar together, amounting to roughly 14 million gallons a day, proved insufficient for ever. the domestic needs of the population, apart from the increased demand from the city's trades and industries. Consequently, after initiation of investigations by Dr. Blaney, the Municipal Corporation sanctioned the execution of the Tansa water works project, originally devised by Major Tulloch, and applied to Government for the loan of the services of Mr. Clerke, an official of the Public Works Department, to carry out the work. Plans and estimates were prepared in 1885 ; the contract for the construction of the masonry-dam was signed and the work was commenced in January 1886; and on the 31st March 1892, the completed works were opened by the Viceroy, Lord Lansdowne. In 1889, during the period of construction, the probability of a water-famine appeared so imminent that the Corporation sanctioned the Powai valley scheme as an auxiliary to Vehar. This consisted of the construction of a masonry-dam to secure the water flowing from 1,700 acres, forming part of the old Powai estate and situated immediately to the south-east of Vehar lake. The lake or emergency reservoir thus formed in 1891 was far too shallow to admit of good water for domestic purposes being obtained and also at too low a level to permit of proper gravitation into the city ; and, on the completion of the Tansa works in 1892, it was therefore abandoned and has never since been utilized. The daily supply that can be stored in the Tansa lake, as at present constructed, is estimated at 40 million gallons.

At the present time (1909), the three lakes, Tansa, Vehar and Tulsi. have a total storage capacity of about 30,000 million gallons above the lowest outlets, arid with a regularly recurring monsoon, there is little prospect of a total failure of the supply. To provide for the growing needs of the city, the Tansa dam has been so designed as to admit of its being raised 15 feet in height, which will then Provide an additional storage of about 12,600 million gallons. The quality of water is generally good, that received from Tansa being considered fit for potation without further purification. The supplies from the various sources are periodically analysed and every care is taken to maintain an abundant supply of uncontaminated water. The following is a brief result of an analysis made during the month of May 1907, when the water level in the lakes was low :—

The average daily supply drawn off from the lakes, exclusive of that lost by evaporation, amounts to about 32 million gallons, i.e., 17 ¼ millions from Tansa, 11 ¼ millions from Vehar and 3 ½ millions from Tulsi. Out these 32 million gallons about 4 million gallons are used for railways, Port Trust, cattle stable, and trade purposes ; hall a million gallons are supplied to the suburbs and the remainder is used for domestic purposes, including the flushing of drains, water-closets, and wastage. It is estimated that about ¾ million gallons are used for road watering. The Fort, with a population of about 100,000, consumes 4 million gallons daily, or about 40 gallons per head. leaving 28 million gallons for distribution amongst the remaining 900,000 odd inhabitants.

The present supply mains from the lakes to the city vary from 24" to 48' di meter, while the distributing and service mains laid within the city range from 3" to 48" diameter.

House service connections for domestic purposes are granted to all private consumers, and vary from ½ " to 3" in diameter. Connections to mills, factories and other industrial concerns vary from 2" to 6" diameter. There are about 22,000 connections now in existence. Hydrants for fire-extinguishing and road-watering purposes are provided in all parts of the city ; there are about 3,400 hydrants now in use. The following table shows the sizes and lengths of the principal mains now in use :—

All the water used for Government, railways, Port Trust, and trade purposes and part of the domestic supply is now metered. There are about 3,000 meters of various sizes ranging from 3/8 " to 6" in diameter in use at present time.

The principal water-works inside the island are the reservoirs and filters on Malabar hill and Bhandarwada hill. The former comprise a clear-water reservoir, settling reservoir, and 7 filter beds with a combined area of nearly 9,000 square yards, which practically filter the whole daily supply from Tulsi. The latter works likewise comprise settling and clear-water reservoirs and 9 filter-beds with a combined area of 15,560 square yards and a filtering capacity of 7 ½ million gallons a day. The reservoirs on Malabar and Bhandarwada hills have storage capacities respectively of 20 million and 12 million gallons. The filters in both cases are constructed of a 24-inch layer of sand, resting upon a 6-inch layer of gravel ; and below the gravel are built brick channels which carry the filtered water away into clear water channels and thence through regulating and measuring sluices into the distributing reservoir. The rate of filtration of Bombay water is calculated at nearly 6oo gallons per square yard per diem. which is equivalent to a lineal velocity of flow of about 5 inches per hour.

Public drinking-fountains, stand-pipes and cattle-troughs have been provided in all parts of the city ; these are taking the place of the old wells and tanks which are now almost entirely abandoned and are, being gradually reclaimed. The public drinking-fountains and stand-pipes, now in existence, number about 150 and cattle-troughs about 60.

The total amount expended on all water-works up to the present time is about 282 lakhs, nearly the whole of which has been met from various loans raised from time to time. The present financial position of the water works scheme is—liabilities 255 lakhs and assets 329 lakhs. Thus the assets, including value of works, is 74 lakhs in excess of liabilities.

Among the most serious accidents occurring since 1892, resulting in the temporary stoppage of the supply from different sources, may be mentioned the bursting of the 42" Vehar outlet main within the Vehar outlet tunnel. This accident occurred on the 30th August 1893, and necessitated the closing of the Vehar supply for about 7 days. In 1892 a land slip occurred at Gibbs' road which carried away a portion of the 24" Tulsi main, and the supply from this source was stopped for about a week. A similar accident occurred in 1907, but caused no serious interference, as Tansa water was supplied to the city and reservoirs through the existing distributing mains. On the 30th July, 1896, about three miles of the 48" Tansa main settled owing to heavy floods and about 5oo feet of piping were entirely washed away. This accident caused a stoppage of the Tansa supply for about 20 days. A portion of the Tansa aqueduct, opposite the Vehar lake, collapsed on the 20th February 1901 and stopped the Tansa supply to the city for 10 days. Owing to the prevailing hot weather, much inconvenience was felt by. the stoppage of this supply. A similar accident to the Tansa duct occurred at Pogaon near Bhiwandi in November 1901, but being the cold season, less inconvenience was felt. The supply on this occasion was stopped for about five days. In September 1904, a portion of the Tulsi tunnel, under the darn, fell in and caused damage to the cast-iron pipes laid therein. This accident caused the supply from the Tulsi lake to be curtailed for a considerable length of time.

Since the completion of the Tansa works in 1892, water has been regularly supplied from the lakes which are amply replenished after each monsoon. There has been no occasion for the inhabitants of the city to return to the use of water from the old wells ; but, owing to the. increasing demands for water for trade and other purposes, it is considered necessary to further augment the supply by duplicating the line of 4.8" pipes. These proposals are now under discussion.

Tansa works

( See Minutes of Proceedings of the Institution of Civil Engineers, 21st November, 1893.)

The Tansa lake is situated at the foot of the Western Ghats, about 55 miles from Bombay, and has a drainage-area of 52 ½ square miles. Its area, when full, is 5½ square miles, with a capacity of about 18,600 million gallons, which after due allowance for evaporation and other losses, suffices for a daily supply of upwards of 40 million gallons. The masonry-dam, which is 8,800 feet in length and 118 feet in height at the highest point, is so designed that it can, if necessary, be raised 15 feet higher, thereby increasing the storage capacity to more than 30,000 million gallons, and the daily supply to 7o million gallons : but this would involve the construction of a second aqueduct along a far less practicable route than that of the existing aqueduct.

The heaviest rainfall recorded at Tansa was 120 inches in 1896 and the lightest 4o inches in 1899, the mean average fall being 108 inches : but so immense is the catchment-area that a fall of less than 40 inches suffices to fill the lake. The surplus waters pass away over a portion of the dam to the south, which is 1,650 feet long and 3 feet lower than the remainder, and thence by depressions in the ground into the old course of the river. These nalas or depressions at the back of the dam have acquired a depth of 20 to 30 feet. Levels are taken after the close of each succeeding monsoon, a comparison of which for several years shows that denudation is not advancing to any appreciable extent. The heaviest flood on record occurred on the 2oth July 1894 and amounted at its maximum volume to 2,500 million cubic feet per second.

Water is drawn from the lake by means of four sluices at different levels, the lowest being 380 feet above the Town Hall datum or about 280 feet above street-level in the Fort, and is always tapped as near the surface of the lake as possible, to ensure the maximum of purity. The conduit which commences at the level of the lowest sluice consists of a masonry channel, 7 feet wide and 6 feet deep, with an arched roof, and is furnished with manholes at about every furlong and cleansing sluices at every two furlongs. It has a downward gradient of 6 inches in the mile, and when full is capable of discharging 40 million gallons a day. The seven valleys on its course, which vary in length from three-quarters of a mile to 11 ½ miles, are crossed by 48-inch cast-iron pipe syphons, with a fall from end to end of in 1,650 and a consequent discharge of about 18 million gallons. Up to the present date a single line of piping only has been laid, so that the full capacity of the aqueduct still remain to be utilized. The longest syphon-line, which crosses the Bassein creek and the low-lying land on either side, is more than 11 miles long, and for roughly, half-a-mile is carried on iron bridges over the three branches of the creek. In all there are about 27 miles of masonry conduit and tunnel, including several long masonry aqueducts and 17 miles of syphon between Tansa and Ghatkopar, the latter point being furnished with a screening and measuring basin, in which can be estimated the quantity of water passing into the 48-inch main running from Ghatkopar to Chinchpugli. At Chinchpugli the 48" main is reduced to 27" and runs as far as Nana's chowk at Gowalia tank, thence it supplies Malabar hill and Bhandarwada reservoirs and the city direct, through the existing distributing mains. The total cost of the Tansa water works was 149 ½ lakhs.

Vehar work

The Vehar lake in Salsette has a drainage area of about 3,900 acres, of which 1,400 are covered by the lake itself. and when full contains about 8,800 million gallons of water. The ratio of the catchment area to the storage area is far smaller than at Tansa. The effects of a poor monsoon are far more lasting than in the case of the larger work, and only a succession of good monsoons can operate to maintain the water at overflow-level.( Lecture on the Water-Supply of Bombay by Mr. Fairlie Bruce. Times of India 1901. It is there recorded that, owing to the deficient rainfall inches) of 1899, the lake was short by 2,000 million gallons in 1900.) The lake possesses three earthen embankments, the large one measuring 84 feet in height and two of smaller dimensions, which were somewhat carelessly constructed in the first instance, and had to be repaired and strengthened at considerable cost about 1871. As originally constructed, the water was drawn off at an upstand tower connecting with a pipe through the main embankment, but justifiable fears being entertained of the safety of this device, it was finally abandoned in favour of an upstand tower at the upper extremity of the dam with regulating sluices to carry the flow into a 42-inch pipe, laid in a tunnel driven through the hill on the east side of the embankment. At the lower end of this tunnel the pipe bifurcates into one of 32 inches (This main is now being diverted between Kurla and Byculla and that portion of the main between Vehar and Kurla will shortly he replaced by a 48" diameter main.)and one of 24 inches in diameter, of which the former. Supplying 7 ¼ million gallons a day, joins the Great Indian Peninsula railway at Kurla and runs thence to the bhandarwada reservoir and filters ; and the latter, supplying 3 to 4 million gallons a day, runs directly to the Vehar filters and thence via Kurla to old Government Hou e, Parel, with a branch to Mahim, Bandora and the northern portion of the island. At the end of the embankment and to the north of the outlet is a waste weir, 603½ feet long, which is capable of disposing of the largest flood likely to occur and thereby preventing the danger consequent upon the escape of water over the top of the earthen-dam. The total cost of the Vehar water-works was more than 45.4 lakhs.

Tulsi works

The Tulsi lake in Salsette, which is the smallest of the three main sources of supply, is situated amid the most charming scenery and lies 52 feet higher than Tansa and nearly 200 feet higher than Vehar. On this account it is able to furnish with water places like Malabar hill and Cumballa hill which cannot be reached by the Vehar supply. But the quality of its water on the other hand is distinctly inferior to that of the other two lakes, owing partly to its size, which is too small to allow of free sedimentation, partly to the absence of algae-absorbing weeds, and partly also to the fact that the prevailing winds blow towards the outlet instead of in the contrary direction, as at Tansa and Vehar. The lake, which covers 33o acres out of a total catchment area of 1,714 acres, is formed by a masonry dam, 85 feet in height, across the original course of the Tulsi nala and an earthen dam of less elevation on the Vehar . side. A waste weir, measuring 142 feet in length, carries the overflow of water into the Vehar lake.

The average rainfall at Tulsi is 104 inches, measured as at Tansa and Vehar near the embankment. As much of the catchment-area of all three lakes is at a far higher level than that occupied by the gauges, it seems probable that the latter do not indicate the total rainfall. The highest recorded fall at Tulsi was 144 inches in 1892, and the lowest 44 inches in 1899. Water is drawn from the lake at different levels into an upstand tower and passes into an iron pipe laid through a tunnel under the embankment ; this tunnel collapsed several years ago, without however causing any damage to the earthen embankment. The water is conveyed to Malabar hill by means of a 24-inch pipe, which, passing Marole about 4 ½ miles from Andheri and Bandora, skirts the west side of the Bombay, Baroda and Central India railway line as far as the race-course, and thence runs up by the Pedder and Gibbs roads to the reservoir. The pipe supplies about 3 ½ million gallons a day. The total cost of the Tulsi works was 37.6 lakhs.