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Solomon’s Pools and relating aqueducts, the heart of Jerusalem’s past water supply

The Solomon Pools

Although the legend attributes the pools to King Solomon, they are certainly younger. Their construction was probably gradual, going back to the 2nd century BC while certain waterworks took place during the time of Herod the Great (37-4 BC).

The three pools stretching across the Artas valley in massive masonry are constructed in steps, each at a level around 6 meters lower than the one above it. They are partly hewn in the rocky bed of the valley and partly built of large hewn stones. The terms upper, middle and lower pool are used to describe them.   

The three large reservoirs have a total holding capacity of approximately one quarter million cubic meters. Their dimensions and storage capacity is given in the following table.

The conduits were so arranged that the lowest pool, which was the largest and finest of the three, filled first, and then in succession the others.

Table: Dimensions of Solomon pools according to Mazar (2002)

 

L x W (m)

H (m)

 Capacity (m3

Upper Pool 

  71 x 118

      9,5 - 11,0     

 85.000

Middle Pool 

  135 x 50

  10 - 12

90.000

Lower Pool

 179 x (46 - 81)

   8 - 16

113.000

Total

 

 

228.000 m3

 

As aerial photographs show, the pools are built at the bottom of a drainage basin, surrounded by hills. They were fed by rainwater falling in the drainage basin either:

  • directly, through storm water streams, or
  • indirectly, through water percolating in the ground and spouting at the hill sides in the form of springs.

Besides collecting rainwater from the plains to the west and the output of some local springs, the pools receive the water of two major supplying aqueducts.   

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Related waterworks

Solomon pools were actually part of a wider hydraulic system with a high degree of sophistication. Five different aqueducts, totalling nearly 60 km in length, were linked to Solomon's Pools. The pools were fed by two aqueducts and their water was then distributed through another three aqueducts, two of them reaching Jerusalem and the third reaching the Herodion fortress. These are described below:

Wadi el-Biyar: the 1st supply aqueduct

This is one the two aqueducts feeding Solomon's Pools (from the south). It is 4,7 km long and descends at a gradient of 1,9%. Compared to the other aqueducts in the system, it is the shortest, straightest and steepest. It actually collected water in three ways

  • a) it conducted water from three springs in wadi el-Biyar;
  • b) it collected rainwater from the valley via a series of dams and shafts; and
  • c) along much of its length it was constructed as a tunnel hewn tapping an aquifer layer similar to a qanat (water seeping through the tunnel ceiling). This technique, which the Romans borrowed from the Persians, is found nowhere else in the country.

Built probably during the reign of Herod the Great (37 BC – 4 BC), the el-Biyar aqueduct remained in service for much of the next 2000 years. It was refurbished by the British along with Solomon's Pools in 1924 and provided water for Jerusalem's Old City up until 1967.

Arrub: 2nd supply aqueduct

The other channel feeding Solomon's Pools is the long Arrub aqueduct. It used to gather the waters of a group of springs lying NW of the Solomon pools, following the contours of the ridges and wadis, it would wind around the Judean hills for an astounding 40 km at an equally amazing gradient of only 0,09% ! In straight line the distance between the beginning and the end of the aqueduct is only 10 km.

For much of its length it was a simple channel hewn into the bedrock slopes, plastered and capped with stone slabs. 

Along its way, obstacles were overcome via two methods:

  • tunnelling through some ridges, and
  • elevating the channel on a stone wall/dam in order to cross wadis.

The dating of the Arrub aqueduct is not certain. It is estimated having been built during the Pontius Pilate time (26-36 AD), that is 30-40 years later than the other aqueduct feeding the pools, the wadi el-Biyar.

It seemingly was re-built in the Mamluk period and finally went out of service during the Ottoman times. Its great length made it especially susceptible to damage or clogging, unauthorised tapping of its water, and the pilfering of cap-stones.

Table 2: Supply aqueducts of the Solomon Pools according to Mazar (2002) 

(in m3)

Annual

Daily

Wadi el-Biyar

    91.000  

250

'Arrub

  227.000

625

Local sources *

 42.000

115

Total

 

990 m3/day

Excluding leakages and evaporation during transport
* Local sources: 'Ain Attan, 'Ain Saleh, 'Ain Burak, and 'Ain Farujeh. 
The total storage capacity in the Solomon's pools was 228.000 m3. So it must have taken over 200 days for them to fill, excluding the considerable amount of rain run-off from the el-Hadr plateau near the pools.

Today, below the lower pool, there is a pumping installation that sends the water of the Attan spring to Bethlehem. This was installed in 1919.

 

Upper: the 1st distribution aqueduct

The upper aqueduct starts at Solomon's Pools, runs northward, close to the watershed line, at a higher elevation than its 'lower' counterpart. It skirts around the west side of Bethlehem (parallel to today's Hebron Road), and ends in 'Hezekiah's Pool' in the Upper City of Jerusalem. Its length is 14 km, with an average gradient of 0,28%. Its best-known remains are a still-visible section of stone pipe (part of a siphon) across a shallow valley south of Rachel's Tomb.

The Upper Aqueduct is now thought to have been Herodian in its earliest phase, then re-built in the Late Roman period, and it may have gone out of use after the Byzantine era.

It has not been in use for so long as the Lower aqueduct, and that is why it is not so well documented or well-preserved, only fractions of it survive today.

 

Lower: the 2nd distribution aqueduct

The Lower Aqueduct ran for 21.5 km from Solomon’s Pools (765m altitude) to the Temple Mount (735m altitude). In that distance, it dropped solely 30 meters, for a gradient of 0.14%! Put in another way, for the length of a football field, the floor of the channel dropped only 14 cm!

The original Lower Aqueduct is dated to the Hasmonean period (mid 2nd – mid 1st c. BC). Thus, along with one or more of the Solomon’s Pools, it is (in its original form) the oldest part of Jerusalem’s aqueduct system. Its construction was meant to alleviate the water shortage that arose at that time in Jerusalem, since the springs and pools in the city were not sufficient for the needs of the growing population and the myriads of pilgrims visiting the Temple.

Of course, it has been restored and/or rebuilt several times throughout its millennia on and off life span, up until 1967 when it ceased to supply water to the Old City.

From Solomon’s Pools it leads northward and runs beneath the town of Bethlehem through a tunnel, mostly blocked today, and soon after a second tunnel of 400 m. This second tunnel (crossing Armon Hanatziv Ridge from south to north) “saved” builders from constructing a 3.5 kilometer bypass to go around the side of the mountain. For its quarrying and maintenance, six vertical shafts descending underground to the aqueduct were constructed.

This tunnel has been renovated by the Elad Foundation and since 2005 is open to the public and can be walked in its entire length from entrance to exit. (Read more in PRESENT STATUS of the case). 

Other sections and channels of the Lower aqueduct in and around Jerusalem can be traced with a little effort from the modern visitor. 

The Herodion distribution aqueduct

This aqueduct descends eastward from the Solomon’s Pools, through the Artas Valley and ends at Herodion, the fortress of Herod the Great dated to the late 1st century BC. Herodion was a large complex (5 hectares) including a fortress, a palace and gardens so had high water needs, covered also through cisterns.

This aqueduct was originally perceived having its source at the spring of Artas, but more recent analysis and excavation show it to be connected to and fed by Solomon’s Pools, particularly the lower pool. Its total length is about 5 - 6 km.

 

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