size of bathroom waste pipe

I tried to fit a 40mm push fit on a bathroom waste pipe but it doesnt fit on the pipe,my question is what sizes can you buy for bathroom waste pipes,i thought it was 40mm but it must be slighlty bigger .

Chances are you have a 40mm solvent weld pipe - as yiu have discovered it doesn't fit into pushfit.

Depending on what you're up to, a compression will fit both types.

As said try a compression. Push fit varies in nominal size between manufacturers. Solvent is a standard size to confuse matters....

So a solvent weld joint will fit,so 40 mm waste pipe comes in different sizes

I think the origins of the differences were accidental, but have been retained intentionally to stop someone trying to fit solvent weld fittings to pushfit pipe. It may appear to work initially, but the joint will soon fail because the solvent doesn't bond to the plastics used in push-fit systems (you don't want to suddenly dump a bathful of water on top of your ground floor ceilings when a joint does fail).

Push-fit systems were developing at about the same time as metrication took place. Some manufacturers probably specified Imperial dimensions, and others metric. Once their specs. were set, they couldn't easily be changed without creating even more compatability problems.

Now metric measurements are standard, all the systems are described by the nominal size of 40mm, because they are all designed to fit threaded 40mm waste fittings.

Fortunately, 'universal' compression fittings can be used to marry just about any two systems together.

So you can buy either waste pipe for push fit or solvent joint?The pipe i tried to fit the push fit is only about 14 years old so i would of thought it would be metric.

Waste comes in the 2 types, solvent and pushfit. Only solvent fittings are compatible with solvent pipe, push fit with pushfit pipe.

It is quite possible your existing pipework is solvent, in which case NO pushfit will fit. Or it could be pushfit from a different manufacturer, i.e. Marley wont fit Osma, or Polypipe wont fit Terrain's push fit range.

Either use a compression joint to adapt your existing pipework to your new installation, or replace the lot with new.

And just to confuse things, MacAlpine do Surefit. Different size again (bigger)