Pop Quiz - What is this pipe type and fitting?

[aaaant]

Hi,

I've found a leak at a "T" junction in the hot water supply to the shower/sink. In a newly built apartment in the U.K.

In the picture (if you look above the copper connection) you can see a 25mm diameter grey pipe and pipe "T" junction.

Any ideas on this pipe system?

Thanks

 

[ShaunCorbs]

If it's newly built it will be guaranteed get the builders back

 

[aaaant]

o.k, it's not that new. 2013, out of warranty etc...

 

[ShaunCorbs]

ive remembered where ive seen them

its marley equator push fit