No, you generally should not use 32mm waste for a kitchen sink; 40mm (1½") is the standard and recommended size for kitchen sinks, baths, and showers because they handle higher water volumes, while 32mm (1¼") is for smaller fixtures like bathroom basins. Using 32mm for a kitchen sink risks frequent blockages as the smaller pipe can't cope with the larger volume of water, grease, and food waste, though adapters exist to connect smaller wastes to larger pipes.
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.
the simple answer is that basin wastes are 1¼” BSP (32mm), whereas bath and kitchen sink wastes are 1½” BSP (40mm).
Waste pipe sizes
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 average kitchen sink's waste coupling size will have a bottom diameter size of 22-23 mm. Check your sink's size and buy the waste coupling accordingly.
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.
Kitchen sinks typically handle more water and solids, necessitating a larger drain pipe. As mentioned, kitchen sinks use a 1 1/2 inch pipe, while bathrooms often utilize 1 1/4 inch pipes. This difference helps in managing the flow of water, preventing backups that can occur in smaller pipes.
All basin wastes are the same size at 11/4" or 32mm. All bath /sink wastes are 1½" or 40mm BSP (British Standard Pipe).
How to measure basin waste size
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.
If the pipe is too small, water won't drain fast enough, and you could have plumbing problems.
Standard kitchen sink dimensions are 22 inches long by 30 inches wide, with an average depth of 7 to 10 inches. However, you can find a wide range of common sizes to suit your needs. 24 to 25 inches long: Kitchen sinks are considered small at 25 inches and under.
Standard pipe size for kitchen sinks: The Uniform Plumbing Code (UPC) requires a minimum 1.5-inch drain pipe, but 2 inches is commonly used for higher water volume.
The limits can be very restrictive and are as little as 1.7m for a 32mm waste pipe to a wash hand basin. By increasing the size of the pipe, you can place the fitting further away – typically between 3 and 4m away for a 50mm pipe.
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.
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.
Waste pipe overview
Typically, 32mm waste pipes are used in bathroom hand basins, 40mm is used for kitchen sinks, showers and bathrooms whereas the largest, at 50mm, is for commercial applications or systems which connect multiple waste pipes into one single flow.
Universal Basin wastes are compatible with all basins, regardless of overflow or not. They can be converted into click clack basin wastes for those with overflows, or the top can be swapped to a freeflow waste mechanism that cannot be closed for those without overflows.
32 mm (1.1/4") BS EN 1451-1 plastic pipe. Do not solvent weld. The actual pipe size is approximately 34.5 mm o.d. x 31 mm i.d..
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.
What Is Standard About Kitchen Drains? In the United States, the standard kitchen sink drain hole diameter is 3.5 inches (90mm). This size accommodates most common basket strainers and garbage disposal units, which are designed with this specification in mind.
A 1 1/2-inch PVC pipe is the most common size for bathroom and kitchen sink drains.
PVC is a great option for:
Sink, toilet, and bathtub drain lines. Vent stacks. Main water supply line.