There is in fact two pools of Siloam in the Silwan district, south of the temple mount: an upper pool and a larger what is considered a larger public bath around 50 metres to the south. The original construct is somewhat difficult to determine because of both works by Hadrian (The shrine of the four nymphs or Tetranymphon) in 135AD and later byzantine construction works in the time of Theodosius II (410-460AD) His wife, Aelia Eudocia (originally from Antioch) in ca438AD because of marriage problems went on a pilgrimage to Jerusalem and returned with numerous relics. During this pilgrimage work on and surrounding the pool was undertaken under her direction. The upper (now called the byzantine) pool contains remnants of a church built under her direction. The Church was destroyed by the Persians in 614AD. A mosque was built adjacent to the site ca1890.
The lower pool was only recently discovered (2004) and measures up to 235 ft / 72 m wide. The lower pool, with its three sets of (5) steps, is plastered, but underneath evidence of a stone-lined pool with coins dated to the rule of Alexander Jannaeus (104-76BC) were found. (These coins were still in use until around the time of Christ, and I have examples in my collection found at this pool) This was probably the original pool mentioned in the gospel record. John 9:6-11 One corner of the pool contained debris from the destruction during AD70 contained coins from this period. The pool being one of the lowest points in the city would naturally have collected the detritus.
The lower pool was used for ritual cleansing, particularly during the feast of tabernacles according to rabbinical records. [some works of the Torah, 4QMMT esp 4Q396 frgs1,2]
Siloam means sent, and the meaning is explicitly given in John 9:7. The language of this mission is within the events of John 9. Jesus would say “I must do the works of Him that sent me while it is today” 9:4 and later to the blind man: Go! and the man went John 9:7,11.
The mission to which we was sent was to create spiritual sons. John 1:12 So the parable within the events of John 8,9 contain the dispute of the nature of fatherhood in the creation of sons. [see 8:25 who (of whose father?) art thou, 8:37,38,39,41,42,44,49,54,56] The Pharisee felt content that naturally being from Abraham gave a distinction before God. But the nature of their relationship with Him was predicated on a)what mother they came from: Hagar or Sarah, b)the manner of faith c)their acceptance of the son of God Himself: Christ was to pass by them 9:1 thus demonstrating the character of “I am” 8:58; 9:9 but by their behaviour they demonstrated they were not sons by taking up stones to kill him. 8:59 This context led to the dispute over the nature of the father of the blind man 9:1,3 and the recreation of him by the provision of spiritual sight in the depiction of clay, the material from which Adam was made. Gen 3:19 The pool then represents the method by which men without a relationship with deity can be created sons of God. It commences as a process of living waters of Gihon cleaning a man’s sight / mind.
Isaiah had indicated the nation had previously refused the waters of Siloah that go softly, Isa 8:6. This was the offering of the testimony to be sealed within the disciple 8:16,20. In the context of Isaiah the message is the same: the revelation of Emmanuel, that is God with us; that God would reveal himself, first in his own son, but then in other children through their faith that God could operate within them: “Behold I and the sons which Yahweh has given me! 8:18 Sanctify Yahweh of armies himself! let him be your ruling inspiration, let him be your inspiring awe! and he shall be for us a sanctuary! 8:13,14 This is the glad tidings of Isaiah see Isa 40.
Further reading: Hershel Shanks, “The Siloam Pool Where Jesus Cured the Blind Man.” Biblical Archaeology Review 31, no. 5 (September/October 2005): 16–23. http://www.soc-wus.org/siloam.pdf