Hastings' Dictionary of the Bible 
SILOAM (‘waters of Shiloah ,’ Isaiah 8:6; ‘pool of Siloah ’ [RV [Note: Revised Version.] Shelah ], Nehemiah 3:15; ‘tower in Siloam,’ Luke 13:4; ‘pool of Siloam,’ John 9:7; probably identical with the ‘king’s pool’ of Nehemiah 2:14 ). The name survives to-day in SilwÃ¢n , the name of the village which occupies the steep E. slopes of the valley of the Kidron from opposite the ‘Virgin’s Fount’ ( Gihon ) to near BÃ®r Eyyub (En-rogel). The village consists of a northern, older section inhabited by Moslem fellahÃ®n , and a small, southern quarter belonging to immigrant Yemenite Jews from Arabia, while still farther down the valley is an isolated row of huts allotted to the lepers. All the site now occupied by the fellahÃ®n has been built upon in ancient times, and the whole area is riddled with cave dwellings, cisterns, rock-cut steps, and ancient tombs. Some of the caves have apparently served the purposes successively of tombs and chapels, while to-day they are dwellings or store-houses. It may be considered as certain that in NT times, and probably for some centuries earlier, there was a considerable village in this situation. The ‘tower’ which fell ( Luke 13:4 ) may have been a building similar to many to-day perched on the edge of the precipitous rocks above the Kidron. Immediately across the valley, to the N. of Siloam, in the very bed of the Kidron, is the Virgin’s Fount (See Gihon), the original spring of Jerusalem. In early times the water of this spring, after probably filling a pool here, ran down the valley; at a later period the surplus supply was conducted by an aqueduct built along the N. side of the valley (partially excavated near its W. end), to a spot where is situated to-day a dry pool known as Birket el-Hamra . Remains of this aqueduct have been traced. As the water supply was, under this arrangement, vulnerable to attack, king Hezekiah ‘stopped the upper watercourse of Gihon and brought it straight down to the west side of the city of David’ ( 2 Chronicles 32:30; cf. 2 Chronicles 32:4 , 2 Kings 20:20 ). The work thus described is the famous Siloam tunnel , 1700 feet long. This runs in an extraordinarily serpentine course from the Virgin’s Fount, and opens in the TyropÅ“on Valley under the name ‘Ain SilwÃ¢n , or the ‘Spring of Siloam,’ to pour its waters into the pool known as Birket es-SilwÃ¢n , or the ‘Pool of Siloam.’ These may have been ‘the waters of Shiloah that go softly,’ a great contrast to the mighty Euphrates ( Isaiah 8:6-7 ). Close to the lower opening of the tunnel was found, in 1880, a Heb. inscription giving an account of the completion of the work. Although undated, there is every reason to believe that this is a contemporary account of Hezekiah’s work, and if so, it is the oldest Heb. inscription known.
The original Pool of Siloam, of which the present Birket occupies but a part, was excavated by Dr. F. Bliss, and was shown to have been a rock-cut reservoir 71 feet N. to S. by 75 feet E. to W.; and just outside its W. edge was found a flight of ancient rock-cut steps, probably those mentioned in Nehemiah 3:15 . A covered arcade, 12 feet wide, had been built, probably about NT times, round the four sides of the pool, and a division ran across the centre to separate the sexes when bathing. Such was probably the condition of the pool at the time of the events of John 9:7 . The surplus water of the pool leaves by a sluice at its S. end, and traverses a rock-cut channel to reach the gardens of the Siloam villagers. S. of the Birket es-SilwÃ¢n is a walled-in area which in recent times was a kind of cesspool for the city, the sewage coming down the TyropÅ“on Valley (now diverted to its proper sewer again) being there stopped by a great dam across the valley. On this dam, at one period, ran the city wall, and Dr. Bliss proved by excavations that it was supported by buttresses of great strength. The area shut off by this dam is the so-called ‘lower Pool of Siloam’ or Birket el-Hamra , and may have been used at one time to store surplus waters from the upper pool. Probably it was the ‘reservoir’ (RV [Note: Revised Version.] ) or ‘ditch’ (AV [Note: Authorized Version.] ) ‘between the two walls, for the water of the old pool’ ( Isaiah 22:11 ), that is, the reservoir to which the water from the ‘old pool’ at Gihon was conducted by the earlier aqueduct referred to above, while the dam itself is with some probability considered to be the ‘wall of the pool of Siloah by the ‘king’s garden’ ( Nehemiah 3:15 ). The water of the ‘Ain SilwÃ¢n is naturally, like that of its source (Gihon), brackish and impregnated with sewage; it also runs intermittently.
E. W. G. Masterman.
Smith's Bible Dictionary 
Sil'oam. (Sent). Shiloach , Isaiah 8:6; Siloah , Nehemiah 3:15; Siloam , John 9:11. Siloam is one of the few undisputed localities, in the topography of Jerusalem; still retaining its old name, (with Arabic modification, Silwan ), while every other pool has lost its Bible designation. This is the more remarkable as it is a mere suburban tank of no great size, and for many an age, not particularly good or plentiful in its waters, though Josephus tells us that in his day, they were both "sweet and abundant."
A little way below the Jewish burying-ground, but on the opposite side of the valley, where the Kedron turns slightly westward and widens itself considerable, is the fountain of the Virgin, or Um'Ed'Deraj , near the beginning of that saddle-shaped projection of the Temple hill, supposed to be the Ophel of The Bible, and the Ophlas of Josephus. At the back part of this fountain, a subterraneous passage begins, through which the water flows, and through which a man may make his way, sometimes walking erect, sometimes stooping, sometimes kneeling, and sometime crawling, to Siloam. This conduit is 1708 feet long, 16 feet high at the entrance, but only 16 inches at its narrowest tributaries which sent their waters down from the city pools or Temple wells to swell Siloam. It enters Siloam at the northwest angle; or rather enters a small rock-cut chamber which forms the vestibule of Siloam, about five or six feet broad. To this, you descend by a few rude steps, under which the water pours itself into the main pool.
This pool is oblong, about 52 feet long, 18 feet broad and 19 feet deep; but it is never filled, the water either passing directly through or being maintained at a depth of three or four feet. The present pool is a ruin, with no moss or ivy to make it romantic; its sides fallen in; its pillars broken; its stair a fragment; its walls giving way; the edge of every stone was round or sharp by time; in some parts, mere debris, though around its edges wild flowers, and among other plants, the caper trees, grow luxuriantly. The present pool is not the original building; it may be the work of crusaders, perhaps even improved by Saladin, whose affection for wells and pools led him to care for all these things. Yet the spot is the same.
This pool, which we may call the second, seems anciently to have poured its waters into a third, before it proceeded to water the royal gardens. This third is, perhaps, that which Josephus calls "Solomon's pool," and which Nehemiah calls the "king's pool." Nehemiah 2:14. The expression in Isaiah 8:6 "waters of Shiloah that go softly," seems to point to the slender rivulet, flowing gently, though once very profusely, out of Siloam into the lower breadth of level, where the king's gardens, or royal paradise, stood, and which is still the greenest spot about the Holy City.
Siloam is a mere spot even to the Moslem; much more to the Jew. It was to Siloam that the Levite was sent with the golden pitcher on the "last and great day of the feast" of Tabernacles ; it was from Siloam that he brought the water which was then poured over the sacrifice, in memory of the water from the rock of Rephidim; and it was to this Siloam water that the Lord pointed, when he stood in the Temple on that day and cried, "If any man thirst let him come unto me and drink." The Lord sent the blind man to wash, not "in", as our version has it, but "at" (eis), the pool of Siloam; for it was the clay from his eyes that was to be washed off.
Hastings' Dictionary of the New Testament 
SILOAM. —Josephus ( BJ v. iv. 1) places the spring at the mouth of the Tyropœon Valley. This, and references of later writers, point to Birket Silwân , on the slope S. of the Temple area. A larger pool, Birket el-Hamra , now almost filled up, lies lower in the valley. Birket Silwân is built within the rock-hewn space occupied by the original pool, 75 ft. × 71 ft. The water was approached by steps cut in the rock. In NT times a covered arcade within the pool, 22½ ft. high and 12 ft. wide, ran round the four sides. From ‘ Ain Sitti Maryam , the Fountain of the Virgin, on the slope below the eastern battlements, a conduit led the water to the pool; but, probably in Hezekiah’s time, a tunnel was cut through the rock, and the fountain apparently covered over, as Josephus does not seem to have known it apart from Siloam. An inscription in ancient Heb. characters was found on the wall of the tunnel in 1880, which gives an account of the cutting. The tunnel is about ⅓ of a mile in length. It is bent as if to avoid obstructions. Two shafts to the surface, at important points, would afford guidance as to direction.
The spring is intermittent. During the rains it may flow twice a day, but in the late summer, once in two days. Such springs are held in superstitious reverence, and credited with power to heal many diseases. Josephus pronounces the water good and plentiful, and says that this and other fountains flowed more copiously after falling into the hands of Titus.
The phrase ‘tower in Siloam’ ( Luke 13:4) perhaps indicates that this part of the city was called Siloam, ‘the tower’ being part of the adjoining wall.
A church was built above the pool in the 5th cent., and later was altered by Justinian. Ruins, possibly of this building, block a great part of the pool.
On the last day of the Feast of Tabernacles, water from this fountain was poured on the altar (Neubauer, Géog. du Talm. [Note: Talmud.] 145). In the 10th cent. the water was ‘good’ (Mukaddasi); it is good no longer, percolating, as it does, through vast accumulations of refuse. The village of Siloam, Kefr Silwân , on the E. slope of the valley, over against the pool, dates from post-Arab times. Its handful of poor inhabitants still use the impure water for domestic purposes.
American Tract Society Bible Dictionary 
John 9:7,11 , or SHILOAH, Nehemiah 3:15 Isaiah 8:6; a fountain and pool at the vase of the hill Ophel, near the opening of the Tyropoeon into the valley of the Kidron on the south of Jerusalem;
"Siloah's brook, that flowed
Fast by the oracle of God."
The pool is now an artificial stone reservoir, fifty-three feet long, eighteen feet wide, and nineteen feet deep. Steps lead to the bottom of the pool, three or four feet above which the water flows off southeast to water the cultivated grounds in the valley below. The fountain is in an arched excavation in the foot of the cliff above the pool; and the small basin here is connected by a winding passage cut through the solid rock under the hill Ophel, with the "Fountain of the Virgin" eleven hundred feet north on the east side of Mount Moriah. See Bethesda .
This passage was traversed throughout by Dr. Robinson. The water flowing through it is tolerably sweet and clear, but has a marked taste, and in the dry season is slightly brackish. It is thought to be driven from the reservoirs under the ancient temple area, and in part from Mount Zion. It runs "softly," Isaiah 8:6 , but ebbs and flows in the "Fountain of the Virgin," and less perceptibly in that of Siloam, at irregular intervals. Thus the water rose more than a foot in the upper fountain, and fell again within ten minutes, while Dr. Robinson was on the spot. He once found a party of soldiers there washing their clothes, John 9:1-11 and it is in constant use for purposes of ablution. At Siloam also the water is used for washing animals, etc.
Nothing is known respecting the "tower" near Siloam, the fall of which killed eighteen men. The ancient city wall is believed to have enclosed this pool. Christ teaches us by the above incident that temporal calamities are not always proofs of special guilt, Luke 13:4,5 , though the utmost sufferings ever endured in this world are far less than the sins of even the best of men deserve, Lamentations 3:39 .
Holman Bible Dictionary 
John 9:7 ,John 9:7, 9:11 uses the etymological significance of the term Siloam for a play on words to press the point that the blind man was sent to Siloah by one who was Himself the One who was sent. To gain his sight, the blind man went to and obeyed the One who was sent. Luke 13:4 is a reference more to an unknown tower at Siloam than to Siloam. The tower may have been an aborted effort to protect the water supply. The theological issue of Luke 13:1 does not hinge on the geographical issue of Siloam.
The pool, created by Hezekiah and known by Jesus is still a source of water today.
John R. Drayer
Kitto's Popular Cyclopedia of Biblial Literature 
Sil´oam or Shiloah . Neither of these passages affords any clue to the situation of Siloam; but this silence is supplied by Josephus, who makes frequent mention of it as a fountain (De Bell. Jud. v. 4, § 1, 2), and indicates its situation at the mouth of the valley of Tyropoeon, where the fountain, now and long since indicated as that of Siloam, is still found. The pool of Siloam is within and at the mouth of the valley of Tyropoeon, and about eighty paces above its termination is that of Jehoshaphat. The water flows out of a small artificial basin under the cliff, the entrance to which is excavated in the form of an arch, and is immediately received into a larger reservoir, fifty-three feet in length by eighteen feet in width. The water passes out of this reservoir through a channel cut in the rock, which is covered for a short distance; but subsequently it opens and discloses a lively copious stream, which is conducted into an enclosed garden planted with fig-trees. The small upper basin or fountain excavated in the rock is merely the entrance, or rather the termination of a long and narrow subterranean passage beyond, by which the water comes from the Fountain of the Virgin. This has been established beyond dispute by Dr. Robinson, who, with his companion, had the hardihood to crawl through the passage. It is thus proved that the water of both these fountains is the same, though some travelers have pronounced the water of Siloam to be bad, and that of the other fountain good. It has a peculiar taste, sweetish and very slightly brackish, but not at all disagreeable. The most remarkable circumstance is the ebb and flow of the waters, which, although often mentioned as a characteristic of Siloam, must belong equally to both fountains. Dr. Robinson himself witnessed this phenomenon in the fountain of the Virgin, where the water rose in five minutes one foot in the reservoir, and in another five minutes sunk to its former level. The intervals and the extent of the flow and ebb in this and the fountain of Siloam, vary with the season; but the fact, though it has not yet been accounted for, is beyond dispute.