Bath leaking under plug/waste water outlet

[chazzyB]

Bath was fitted about 20 years ago and there was a leak about 10 years ago where the water was coming through the downstairs ceiling. The wife called an emergency plumber on the home insurance who came out and said oh, the bath waste pipe is leaking so he tightened it up and that was "fixed" until today when the downstair ceiling started dripping again.
The bit where the black piece meets the bath feels wet and around the lower white bit. I don't know if the crusty crud is limescale or failed sealant.

How to fix this? Take the whole thing off and replace? Is this just going to be a crusted worn washer, the "sealent"/"cement" around the top of the black bit?
How does the black piece fix to the actual bath? is it s crew fitting? Are these a standard size? if not what do I have to measure?
(I spent an hour in local toolstation recently while they tried to find a replacement "50mm" washer where everything they had was labelled differently either ID or OD)


Lastly, is this something that has been sealed by the crud until mr muscle was recently poured down?

 

[terryplumb]

Needs stripping down ,cleaning up and a new waste with combined overflow fitted.
The white trap should have a new seal fitted as well.
There is a screw in the plug hole that bolts the part under the bath to the part at the top.

 

[chazzyB]

Needs stripping down ,cleaning up and a new waste with combined overflow fitted.
The white trap should have a new seal fitted as well.
There is a screw in the plug hole that bolts the part under the bath to the part at the top.

I can only find the bath waste and overflow with integrated plug hole (the in the bath part) so will have to replace it all?
Are these a standard size? and it the trap fitting a standard size?
I hope the overflow part is detachable, because that might be impossible to reach the fitting. We never fill the bath anyway, only showers so the overflow is redundant.

 

[Agile]

With the proper components it does not need any sealant.

Although some less competent installers still think they should use it. But using it can hide improperly fitted or tightened parts.

 

[terryplumb]

I can only find the bath waste and overflow with integrated plug hole (the in the bath part) so will have to replace it all?
Are these a standard size? and it the trap fitting a standard size?

Yes bath waste etc all standard size.
Why can't you reach the overflow ,that will need replacing as it comes as a kit.

 

[chazzyB]

Yes bath waste etc all standard size.
Why can't you reach the overflow ,that will need replacing as it comes as a kit.

It's ok, I can reach it. it's around in the corner and I only have access from the front, so thought it would be more difficult to reach the back side to undo and fit a replacement