Clear slime and black bacteria seeping out of kitchen mixer joints

[Amanico]

My mother has been away on holiday for a few weeks and she has a kitchen mixer tap that has a very slow drip nothing significant - been like that for a couple of years. The mixer has a a long spout that can be rotated between sink and drain bowl. She left the house meticulously clean.

I came to check on the house a week ago and all was ok.. I returned a week later and found that the sink had marks around the side that showed it had totally full of a dried green and black bacteria filled liquid.

Around the base of the tap and around the plug hole was evidence of a thick clear "mucus" thick liquid and a white dried deposit leaking from all of the tap joints.. there is evidence of a black furry bacteria too.

I assume whatever came out filled the sink because the thick mucus -like liquid prevented whatever it was from draining quickly and hence filled the sink.
I also assume that whatever it was stopped flowing from the tap joints and the full sink then drained away slowly leaving behind the evidence of how it was on the sides of the sink.

Beneath the sink there is a branch of to an outside toilet and sink and a washing machine.
Running the taps in the outside toilet sink and flushing the toilet water runs clear.. upstairs bathroom it is all clear. combi boiler pressure normal and heats DHW no problems and water runs clear. Could it be from the washing machine that no issues with its water solenoid valve as it has has no leaks.

Even running the kitchen tap, the water runs clear!

I am totally stumped.
Has anyone seen anything like it?

 

[ShaunCorbs]

Needs a new tap it’s because the cartridge is leaking internally

 

[Amanico]

Needs a new tap it’s because the cartridge is leaking internally

Thanks for the reply Shaun.
That disgusting green and black bacterial mould and clear slime are like something from a horror movie.
But it has happened spontaneously - filled the sink with that black and green slime and furry bacteria growth and then stopped just as quickly as if nothing ever happened - appears to be working back to normal. there was a lot of it as the entire basin sides are covered in it too.
It has never leaked before and since that incident is back to normal.