I need to repalce the plastic ring/washer that screws into the end of my bathroom sink tap(where the water comes out). I do not know what its correct name is so do not know what to ask for. Please can you help me?

Bronya, October 2008

R U referring to the Aerator?
If so, U would unscrew it (it may may have several small round screens, "O" ring, restrictor etc)
You will have to know the brand name of the faucet to find a replacement.
Discard old, replace new !!

Cary., December 2008

It might be called an aerator

They screw on the very end of the spout and smooth out the flow and are often black plastic. Sometimes they clog up in hard water areas but you can unscrew it and give it a clean.

Sexy, expensive metal aerators are also sold to limit the flow.

If it's not an aerator then it's a tap-washer - goes inside the body of the tap and controls the rate of flow.

Peccavi, October 2008

It's simply called 'a tap washer'.

Rich, October 2008