size measurement

It's the outer diameter you measure.

Outer. Waste pipe will normally come in the following sizes, 32mm, 40mm, 50mm and for soil 110mm

The measurement that you need is the outside of the pipe. 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. But most commonly, solvent weld fittings are used. However, there is another type of plastic waste pipe. This is the “pushfit” type. They are only used with “ring seal” fittings. These fittings all have a rubber O ring within them to create a seal. This pipe is neither 40mm or 32mm. And therefore cannot be used in conjunction with the first pipes mentioned. I hope this helps.

Hi you measure the out diameter of the pipe, as you no you are inserting the pipe into the waste fitting connection. Regards V T Plumbing & Building Services.

To ensure fitting need measure the outer diameter, on waste pipe kitchen and bathrooms, there are 2 types of pipe one is cement solder the other is pushfitt and compression fitting, so it may say 32mm but they have little difference and need to get the right ones. The inner diameter is to calculate the amount of water going through the pipe section

Instead depending which waste pipe you need if it’s a basin waste, it’s 32mm, & if it’s bath, sink or shower it’s 40 mm When you purchase it from say, screwfix they will know straight away.

Usually the outside measurement is used.

external