Yes, you can use 32mm waste pipe for low-volume fixtures like hand basins, bidets, or even washing machines (as they rarely run simultaneously), but for higher flow appliances like kitchen sinks or showers/baths, the larger 40mm pipe is generally recommended to prevent blockages and ensure proper drainage, with 50mm used for commercial or combined systems.
Standard waste pipe is either 40mm (1 1/2 inch) or 32mm (1 1/4 inch). 40mm pipe is used for kitchen sinks / washing machine waste / baths / showers. 32mm pipe is used for basins / sinks found in bathrooms and cloakrooms. Both these sized pipes can be used with compression fittings.
All basin wastes are the same size at 11/4" or 32mm. All bath /sink wastes are 1½" or 40mm BSP (British Standard Pipe).
32mm nominal internal bore (outside diameter is bigger at approx 34.5mm) plastic waste pipe x 1 foot, available in white, black or grey. This size is popular for bathroom basin wastes.
If a 32mm waste pipe is longer than 1.5 mtrs, a 40mm pipe 3 mtrs, and a 50mm pipe 4 mtrs, then the options are to increase the pipe size to the next size, and/or install an air admittance valve.
Waste pipe sizes
32mm: Typically used for appliances presenting low volumes of water to the system (e.g. small hand basins). 40mm: Normally used for kitchen sinks, showers and baths. 50mm: A large pipe commonly suited to commercial applications or connecting multiple waste pipes to a single flowing system.
The Bottom Line on Shared Drain Systems
Can a shower and sink share a drain effectively and reliably? Yes, when the system is properly designed and installed. This isn't about cutting corners or saving money upfront – it's about creating a better-functioning bathroom that's easier to maintain long-term.
If the pipe is too small, water won't drain fast enough, and you could have plumbing problems.
50mm & 90mm Shower Wastes
The larger size in diameter means that waste water can be efficiently removed faster and help your shower to remain clean and hygienic, prevent unwanted odours in the bathroom.
1" pipe actually has an outside diameter of 33.4mm. 1" pipes or spigot fittings (measuring 33.4mm outer diameter) will slot inside one end of this socket to be solvent welded, and 32mm pipes or spigot fittings will slot inside the other end.
This waste pipe fitting with 40mm spigot connection on one end and 32mm compression socket on the other end will reduce the 40mm socket to 32mm one. It needs to be fitted to existing 40mm compression waste fitting and then it will create the same but 32mm one where 32mm waste pipe can be connected.
In conclusion, using a larger sewer pipe at the start of a system is a proper choice to ensure proper flow, especially when the slope is shallow. As the slope steepens, a smaller sewer can be used since the water flows faster.
Typically, residential toilets require a drain pipe size of 3 inches in diameter to accommodate the flow and prevent blockages. However, the correct size can vary depending on the specific fixture units and the overall demand placed on the drainage system.
the simple answer is that basin wastes are 1¼” BSP (32mm), whereas bath and kitchen sink wastes are 1½” BSP (40mm).
They look pretty similar. They're both made from the same form of unplasticised PVC (PVC-U) but the difference is in the wall thickness. Schedule 40 PVC pipes are made with thicker walls that stand up to low pressure applications. Whereas PVC DWV piping has thinner walls and is not made for pressurized applications.
1 1/4 inch - 32mm Solvent Weld Branch Y Piece. This pipe is often called 32mm, note that this refers to the internal diameter of the pipe and not the external. External diameter of 1.1/4" pipe is 36mm.
PBC, 32mm is for the basin, you really need to connect 40mm for the shower, you will probably end up standing in water if you use the 32mm pipe and probably worse if you have a powerful shower...
A common size for a shower waste is 120mm x 120mm. This size allows plenty of space for the standard 40mm (1½”) waste pipe and drain to be fitted, and provide efficient water removal.
A 32mm waste pipe is typically used for appliances that present low volumes of water to the system (e.g. small hand basins), while 40mm is normally used for kitchen sinks, showers and baths. 50mm, on the other hand, is large to suit commercial applications or connect multiple waste pipes to a single flowing system.
Therefore, if the pipe diameter decreases, the fluid must flow faster to maintain the same flow rate, resulting in a decrease in pressure. Meanwhile, if the pipe diameter increases, the fluid can flow more slowly, and the pressure can increase.
Why Does Waste Pipe Come With Different Sizes – 32mm and 36mm – 40mm and 43mm? Understanding the Basics. Discover the two primary types of waste pipes: push-fit and solvent weld. Each variant boasts distinctive characteristics and applications, providing diverse solutions for various plumbing needs.
Can bath and shower waste join together? Yes, but care should be taken during installation. Since both appliances use the same size pipework (40mm waste pipe), having them connect to the same discharge pipe shouldn't be a problem.
6 Ways to Increase Shower Pressure
Our range of waste pipes range in diameter from 32mm to 50mm as they are only required to carry water, not waste. Therefore, they are also not required to be vented high above ground level.