Knockbracken Reservoir, Saintfield Road, Belfast

This extensive waterworks complex stands on the west side of Saintfield Road and comprises six principal components: a reservoir with related structures, a river bypass channel, a scour valve and channel, water attendants' houses and related buildings, a chlorination house, and miscellaneous buildings.

The Reservoir

The L-shaped open reservoir was created by excavating the east bank of the Carryduff River and placing a large earthen embankment across the valley at its north end. The inside faces are sloped and pitched to their wet sides with rubble stone. Water discharges from the Mourne Conduit into the reservoir at its south end, where a concrete-lined recess in the bank is surrounded on three sides by three-bar metal railing. The water falls over two vertical drops and down an incline into the reservoir. Metal baffle plates across the lower fall and a concrete post at the bottom of the incline break the force of the water and aid its aeration.

Water is abstracted from the reservoir at its north-east end, where two vertical cast-iron standpipes (36 inches in diameter) have valve stocks at the top controlling the flow. Access to these valves is via a metal footbridge supported on two dressed granite piers (drawings show this facing to be over concrete). At the north-west end, the bank is broken to accommodate an overspill weir discharging into the Carryduff River. A footbridge formerly spanned this overflow, but only its cast-iron piers now survive.

River Bypass Channel

The Carryduff River has been diverted around the west side of the reservoir in an artificial channel. Just before entering the reservoir grounds is a small cascade weir which breaks the flow as it passes underneath the public road through two cement-lined segmental-headed culverts. Two concrete-decked metal footbridges cross this channel at the reservoir's overspill. The river then cascades down a series of paired steps, at the foot of which the scour channel meets. This section has vertical random rubble walls. The river then continues down the valley along its natural course.

A short distance south of this complex stands a modern lime dosing plant, similar to those at the Silent Valley and Dunmore.

Scour Channel

On the dry side at the foot of the embankment is a scour channel which falls from east to west and discharges into the Carryduff River channel. This carries the outflow when accumulated silt is being scoured from the abstraction pipes or when the reservoir is being drained. A concrete-lined valve control well stands at its top end. The channel is piped for a short section from the valve chamber, and part of the bank has random rubble revetments. At its bottom end, a series of steps reduces the force of the flow before it meets the river.

Water Attendant's Houses

The original attendant's house, known as Waterworks Lodge, stands on the east side of the reservoir within mature conifer plantings at 591 Saintfield Road. This one-and-a-half storey, three-bay dwelling has a T-plan with a single-storey return in an enclosed yard at the rear. It was vacated approximately six years ago and now lies empty.

The house is oriented east-west, with the top of the T at the east end and principal gables to north and south. The roofs are pitched and covered in natural slate with ogee cast-iron gutters on projecting eaves. Plain bargeboards finish the gable ends, each with framed apex finials. Yellow brick chimneys stand at either end of the main ridge. The walls are lined and painted smooth cement render over a smooth rendered base course (maintained in this state for over three years). A plain platband runs around at sill level on both floors, though it is uncertain whether this is stone or concrete as it is overpainted. All windows have either been sheeted over with plywood or fitted with metal security mesh. Their sills are incorporated in the platbands.

The main facade faces north. At left, the slightly projecting gable of the left front room is accompanied by a verandah running across the facade to the right. This has a monopitched natural slate roof carried on three round metal columns with decorative cast-iron brackets at the top. The verandah floor is laid with alternating red and white tiles. The main door at the left end of the verandah, now sheeted over with plywood, leads into the middle bay. To its right are two 2/2 sliding sash windows. The left gable contains two similar windows with a horizontal drip mould over both. At first floor above the verandah, a gabled dormer rises from the eaves, containing a semicircular headed window with run-moulded architrave. An identical window appears in the apex of the main left gable.

The east wall has two 2/2 sliding sash windows at ground floor (one to each room), each with a horizontal drip mould continuing from the facade moulds. At first floor are two gabled dormers similar to that at front right, each with semicircular headed windows, presumably lighting front and back bedrooms. This wall continues along the yard perimeter, with two 4/4 sash windows lighting the lean-to shed inside the yard.

The south wall, not inspected in detail due to lack of yard access, features a flat-roofed porch at centre with half-landing light above, and single-storey lean-to sheds abutting either side. At right is a semicircular headed window in the gable apex. No window opening exists on the upper left side. The west wall is blank except for a single 2/2 sliding sash window at ground floor. This wall continues at right to form the yard perimeter, with two modern wooden windows along this wall in what may be original openings.

The yard was originally accessed from the south through a wide opening flanked by square pillars with pyramidal caps. This entrance has been narrowed with concrete blocks and a modern pedestrian door inserted. At right, a large modern door has been inserted in the gable of the lean-to to enable garage access.

A short distance south of the lodge stands a single-storey building with enclosed yard. Most recently used as a canteen by grounds staff, it formerly housed a horse and trap belonging to the reservoir's water superintendent. The building is oriented with gables to east and west, with the yard to south. The roof is pitched and covered in natural slate with half-round metal gutters. Plain bargeboards finish both gables, with a framed wooden apex finial on the east-facing gable. The walls are wet-dashed with cement over smooth rendered base; corners and opening trims are also smooth rendered.

The east gable contains two entrances, both now sheeted over with plywood, with a circular window in the apex. The north wall is blank save for a series of metal ventilators. The south gable is blank except for a circular window in its apex. Although the yard was inaccessible, external inspection revealed two wooden doors and two windows along the building's south wall. The yard is entered through two high sheet steel gates flanked by smooth rendered pillars surmounted by pyramidal concrete caps. The yard wall, coped with concrete, rises at the south to accommodate the natural slate roof of a lean-to shed within the yard.

At the entrance to the grounds stands a comparatively modern two-storey brick dwelling (589 Saintfield Road), now privately owned but formerly the home of the reservoir attendant.

Chlorination House and Related Buildings

In the immediate vicinity of the valve well are seven small brick buildings, all with flat concrete roofs and of comparatively recent date. These house flow gauges, valve stocks, and chlorination plant. Also in this area is a relatively modern single-storey dwelling originally built for the chlorination plant attendant. It has since been sold by Water Service and is now in private ownership.

Boundaries

The grounds are bounded along the main road to the east by a concrete wall comprising rock-faced concrete blocks laid in regular courses with stepped concrete copings. Originally a hedge ran along the road, but this was removed when the road was widened and the present wall built. A pair of modern steel gates provides entrance to the grounds at its south end, with another opening at the north. Original drawings show the original entrance gate to have been wrought iron with flanking screen.