In Australia, standard waste pipes vary by application, with common sizes being 40mm for showers/baths, 32mm for small basins, and larger 90mm or 100mm PVC for main sewer/stormwater drainage, though 90mm is increasingly popular for newer installs over traditional 100mm. Always match new pipes to existing sizes where possible, especially for connecting multiple fixtures, but 90mm and 100mm are the go-to for main lines.
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.
For a very long time, 100mm PVC has been the standard diameter for both stormwater and sewer drains. But in the past 5 years or so, 90mm PVC has become much more popular.
40mm waste system is the common size for bath and kitchen sink installation.
Yes, in plumbing, 20mm is generally considered the metric equivalent for 3/4 inch for pipes and fittings, even though 3/4 inch is actually 19.05mm; they are used interchangeably because 20mm is the closest standard metric size to the imperial 3/4 inch nominal bore, especially for fittings like BSP threads.
3/4 inch Copper Pipe – Outside diameter 22.2 mm .
The outside diameter (OD) is not used to find the PVC pipe size; instead, the inside diameter (ID) of the pipe is used, measuring between the inside edges.
Will join 40mm to 43mm and anything in between.
40mm: Normally used for kitchen sinks, showers and baths.
The standard drain line size for a toilet is typically 3 inches in diameter. This size is recommended to ensure proper drainage and to help prevent the inconvenience of clogging. For households with multiple toilets, it is possible to have up to three toilets on a 3-inch common drain.
The 90mm and 100mm are the common sizes of downpipes in most houses. If you are adding another one to your existing set, I suggest using the same size already installed in your house. The 100mm is more often used in underground drainage.
The most common sewer pipe size is four inches in diameter, but there are also six and eight-inch pipes available, which are also sometimes referred to as concrete storm sewer pipe sizes.
This means that you would typically want your water lines to be at least 4.5 feet below the ground level, or possibly even deeper if you live in the or the foothills. The sewer lateral leading from your house out to the municipal sewer main should also be at the same depth, as it could also freeze.
Running waste pipes through joists should be avoided where possible, as any drilling of joists (also known as notching joists) may weaken them and compromise the structural integrity. When you do need to notch a joist, you should use the following rules: Only insert a notch into the top edge of the joist.
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.
A typical toilet waste pipe is 100mm/4 inches in diameter. When a house is being newly built or completely renovated it's relatively easy to route this large pipe from the toilets to the drain.
40 mm (1.1/2") BS EN 1451-1 plastic pipe. Do not solvent weld. The actual pipe size is approximately 41 mm o.d. x 36 mm i.d..
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.
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.
Solvent Weld White 40mm (43mm) Waste Pipe Swept Bend - Pack of 2. Amazon's Choice highlights highly rated, well-priced products available to ship immediately.
40 mm waste pipes are used in areas where higher volumes of water will be entering the system such as baths, showers and kitchen sinks.
It fits the elbow joint on 32 and 40mm waste pipes, once you have drilled the hole using a 52mm core drill. The product's cosy fit into the bored hole means it is designed to seal the hole where a pipe exits a wall.
OD is typically used for PVC pipes and fittings, especially in plumbing-based setups. Knowing which measurement applies to each component ensures compatibility across hoses, pipes, and connectors, making setup easier and your system more efficient.
In Australia, because we are a metric country using an imperial PVC pipe system, it is common to specify pipe by the metric equivalent of the NB size. For example: 2” NB is sold as 50mm pipe, but the actual OD (outside diameter) is 60.3mm & the actual ID (internal diameter) of Shed 80 is 48.5mm.
PVC pipes are generally categorised into four: PVC-U unplasticised PVC), C-PVC (chlorinated PVC), PVC-O (molecular oriented PVC) and modified PVC. Besides sharing many of the same properties, each type of PVC has its own advantages for different applications.