Are you allowed to cut a hole in the main sewer?

[Toddlerteaplease]

My next door neighbors landlord (student house) is converting the garage into an extra bedroom. They've hacked a hole in the drive exposing the sewer pipe and look to be joining a pipe too it. I've just been asked to flush my toilet so they can see which way the water is flowing.
Is this allowed. I'm a bit concerned that it seems very amateurish. (Based on the way the hole on the drive looks!)

Probably a branch sewer pipe rather than the actual main sewer.

it isn't allowed. only certified people are allowed to touch those.
contact the water board.

Ok. That's what I was wondering.

I have spoken to the asset protection team st Severn Trent. All they said was that they should have contacted the new connection team.

Jeez they can’t do that. I looked into connecting our property to the main sewage line and it’s a whole massive thing with attendant massive costs. I would contact the council planning office as that might fall under planning regulations

They would need an agreement with the water company about how they would make the connection including materials and backfill, plus any additional inspection or rodding points.
The builder will do whatever is easiest and will be tempted to skimp on anything that won't cause a problem in the short term.
Make sure you escalate to the right team in the water company otherwise the first you might know is when your toilet is blocked and the drive needs digging up to replace the drain.

Severn Trent told me it was their asset protection team that felt with it. Though they didn't seem bothered and didn't take any details. I know that they applied for planning permission for the project as I got asked if I objected. The join in the pipe looks ok. But I'm not sure how professional they actually are. I'm a bit puzzled as to why they have not aged a join into the the drainage pipe rather than the sewer pipe.