Plumbing & Drainage

Plumbing is the trade nobody looks at until it leaks, so the paperwork is the product. A plumbing package covers the water that comes in, the waste that goes out, and the pumps and tanks between them. SBC 701 sets the sanitary and plumbing requirements, and the consultant's specification names the pipe materials.

Water supply pipework is usually PPR to ISO 15874 for cold and hot lines inside buildings, with copper or stainless steel where the specification asks and HDPE to ISO 4427 for buried and larger-diameter runs. Every system is pressure tested before it is covered, flushed, and disinfected before it is used. Hot water adds insulation and often a return circuit.

Drainage runs on gravity, so levels are the work. Soil, waste and vent stacks in uPVC or HDPE, floor drains, cleanouts and manholes are set out to falls, tested by air or water, and connected at the invert level agreed with the public network. Where the project joins the National Water Company network, the connection follows NWC requirements.

Tanks and booster sets get a line of their own. Storage in GRP, concrete or steel, transfer pumps, VFD booster sets in duty and standby, level controls and chlorination points keep a building supplied when mains pressure is low. Sizing comes from the design demand and the consultant's storage criteria. Fixtures complete the package: WCs, basins, showers, taps, bidet sprays and ablution points, fitted to the schedule with carriers, supports and sealing checked room by room.

Roof drainage deserves attention in a dry country. Short, heavy storms in Jeddah and Riyadh overload undersized outlets, so roof drains, downpipes and overflow outlets are sized to the rainfall intensity the consultant sets. Send the plumbing drawings, the fixture schedule, the specification and the BOQ, with the city and the programme dates.