Water company would never have connected up anything yellow to their network so you may find it is an illicit connection made by bodger the builder.
If the blue pipe is still live then a possible solution might involve in capping off the yellow one and re-purposing the blue. But best to leave that to the water co. now you have got them involved.
Interestingly that's our nick name for him. It's been one nightmare after another. Failed to install tanking on the basement, failed to install ventilation, studs framed with scrap pallet wood, missing insulation, DIY OPA wiring, internal twin & earth cemented under the drive. External lighting trunked in hose pipe, joists all needed sistering as only rated for half the span. Gas pipes not supported over a 5 meter run, all wrong size. Substandard slates on the roof. No drainage in retaining walls. No supports in 3 meter high retaining walls. Drive angle too steep. Not a single square wall and not a single level surface. Interior finished with softwood planks, flooded chipboard flooring all had to be ripped out. DIY window casements, every glazing unit was blown. Gutters, downpipes all missing or damaged. Asbestos used as fence panels. Consumer unit relocated but every cable cut, stuffed in junction boxes and hidden in wet cavity space. List goes on.
So we just assume this is another one of his f**k ups. Been fixing this place for a year and a half and not even a third of the way to being done.
I can’t see any exposed mains voltage or conductors. There’s at least 3 stopcock so there, guessing it’s the blue mdpe one? As per
@HERTS P&D will be interesting to hear/see outcome.
I'm not about to try and renew or replace a live stopcock next to this;
As for the blue one. As I already explained there are two blue coming out the basement internal wall and one blue and one yellow going in. So the yellow is feeding the mains supply.
There isn't much to video it's dripping a couple of drops every second at a rate of about 10 litres every 12 hours. So it's likely going to be the gland washer has failed.
I'll post an update Tuesday evening what the water board say.
You could hire a puddle pump to save you bucketing out the water. Until the board come to have a look.
Thanks its manageable as is for a few days. If it got any worse or someone isn't going to be around to watch it, I can commission the slump pump temporarily.