The only reader-added tag so far is "I'll DIY it anyway".

Wouldn't that be a bath-plug ? Even in this country, them being standard sizes one can buy one in a village shop or newsagent...

It looks like one of the fancier ones that connects by a hidden rod to a wall button. You wouldn't be able to replace that without specialty parts. Or remove it completely and put in an el cheapo rubber plug, but then it wouldn't match.

if its just rubber, you could always just buy a bigger one and trim it down.

Kissmyaxe said:

It looks like one of the fancier ones that connects by a hidden rod to a wall button. You wouldn't be able to replace that without specialty parts. Or remove it completely and put in an el cheapo rubber plug, but then it wouldn't match.

You could probably scrape off the old rubber and make a new gasket with RTV silicone.

Kogasa said:

For important parts, it's best to buy 2-3 spares.

Never buy spares for rubber-based products unless the objective is to throw good money away.