The Colchester Archaeologist 2002 - Colchester Archaeological Trust

Water supply in
Roman Colchester
Water is another of life's necessities, so it
is no surprise that the paraphernalia
required to extract water and deliver it to
people is often found on excavation sites
in and around the town. The discovery of
a water-main or conduit on the St Mary's
hospital site adds to our knowledge of
the water supply to the Roman and later
town.
Excavations at Balkerne Lane in the
1970s uncovered some key evidence for
water supply. A shallow trench running
across the site and heading towards one
of the arches of Balkerne Gate carried
four wooden water-mains (see picture).
Each water-main was made of a series of
straight wooden pipes held together by
flat iron bands hammered into the
thickness of the pipe walls to provide a
water-tight and pressure-resistant joint.
Further evidence was the discovery on
the Balkerne Lane excavation site of two
parallel rows of post-holes which would
have held lines of hefty wooden posts.
This has been interpreted as being the
remains of a Roman aqueduct, which
could have brought water from Lexden
and carried it over the top of the town
wall in a raised culvert (see picture).
After that, we must imagine it being fed
into a water tower of some kind and
redistributed from there along wooden
water-mains to houses and public
fountains in the town. In fact, the Head
Street excavations in 2000 uncovered
what might be the 'rising main'
connection - there was an underground
wooden water-trench with an iron band
which came to an end directly under a
hole in one of the tessellated floors of a
3rd-century Roman house. What happened
above floor-level is not known;
presumably there was a tap and a basin.
Although no waterworks are known
immediately inside the town wall, there
is the suspected one in Castle Park (now
under the children's playground). It was
originally thought to have been a pagan
temple (a mithraeum), but the plan of
the building and the spring which rises in
it suggest otherwise.
The problem at Colchester was that
most of the Roman town was well above
the spring line. This meant that, to
provide a pressurised water supply, the
water had to be raised in bulk from the
springs to high ground where it could
then be distributed in wooden pipes
under pressure. Water could be raised by
the 'Archimedes screw' or with pumps,
but the most likely method was a series
of water wheels.
18
The Romans were
able to provide
pressurised running
water in the town
centre, a standard not
equalled until the
early 17th century.
Water was probably derived from different
sources around the town, but a
major source seems to have been
Chiswell springs, west of the Balkerne
Gate. Another was just east of the
Temple of Claudius, in what is now the
Castle Park. Wells would have been used
along the north side of the walled town
where the water-table was relatively
close to the ground surface.
(For more information about the development
of Colchester's water supply,
see Colchester Archaeological Report 3,
pages 26-8.)
Above: the remains of four wooden
water-mains excavated in the 1 970s at
Balkerne Lane. The mains are curving to
pass under one of the carriageways of
the Balkerne Gate.
Below: reconstruction painting by Peter
Froste of the west side of the Roman
town in the late 1 st century showing the
wooden Paqueduct in the foreground.