- Project plans
- Project activities
- Legislation and standards
- Industry context
Last edited 01 Nov 2020
Sanitary pipework is above-ground pipework that is used to carry water from toilets, sinks, basins, baths, showers, bidets, dishwashers, washing machines, and so on, out of a building to the sewage system. The equivalent underground pipework is referred to as foul drainage and sewers.
According to the Building Regulations Approved Document G, every modern home must have a WC fitted that is connected direct to the drainage system, with a basin fitted next to the WC with a supply of hot and cold water. In addition, every home must have a fixed bath or shower with a hot and cold water supply, and all appliance connections that are connected to the drainage system must have a trap to prevent odours and dangerous gases building up inside.
Sanitary pipework system should be designed according to the Building Regulations Approved Document G and H, and should conform with BS EN 12056:2:2000, 'Gravity drainage systems inside buildings. Sanitary pipework, layout and calculation'.
Traditionally, sanitary pipework was manufactured using metals such as cast iron, copper or lead; however, modern designs predominantly use plastics such as uPVC, high-density polyethylene (HDPE), polypropylene and so on. They are generally connected by some form of welding (such as solvent welding) or using push-fit fittings.
The pipes are designed to different diameters depending on the appliance which they are connected. For example, a WC typically uses a 110 mm diameter pipe; baths, showers, sinks, washing machines use 40 mm diameter pipes; a bidet uses a 32 mm diameter pipe, and so on. The pipes are laid out to a slope or ‘fall’ which allows wastewater to drain away without leaving debris behind and avoiding blockages.
Sanitary pipework is typically connected to a soil vent pipe (SVP) which is a vertical pipe often attached to the exterior of a building that connects the drainage system to a point just above the level of the roof gutter allowing odours to be released. Venting the stack prevents water seals in traps from being broken by pressure build ups in the system.
 Related articles on Designing Buildings Wiki
Featured articles and news
Gaining green support from the carbon giants.
Medieval passageways with spiritual, transport and economic purposes.
Organisation receives accreditation from Investors in People.
Click the button to subscribe.
Communicating the right information at the right time.
Materials can take on different properties to control heat and glare.
Challenges in the construction sector and beyond.
Exploring brick and timber construction techniques.
On wheels or on platforms, micro dwellings are popping up everywhere.
Landlords must now comply with new repair regulations.
You can add articles and help improve knowledge in the construction industry.
Ayo Sokale explains the struggles of being neurodiverse.
Communities, heritage and architecture. Book review.
The voluntary sector continues to shape the debate.