Why is my mains pipe going up the 1st floor?

I have been renovating my ground floor bathroom and while taking the walls back to brick, I found my mains pipe buried in the wall, going up to the eaves. This prompted me to follow the layout of the mains supply and found that although it starts at the ground floor, instead of supplying the bathroom directly it instead loops over the first floor eaves and then goes back down to the ground floor to supply the ground floor bathroom. I have added a diagram to explain it a bit better.

There is also a capped off and cut 22mm copper pipe going from the loft to the first floor eaves.

Could this be due to an older gravity fed system? The boiler is currently in the kitchen (ground floor).

This mains pipe is lead and is in the way of both my current bathroom renovations and my future eaves renovations, so I was thinking I could just go directly from the ground floor mains pipe to the ground floor bathroom copper pipe and then rip the old lead pipe out from the bathroom wall and the eaves. Any reason I shouldn't do that?

Also in terms of doing that, I have bought a PHILMAC Universal Transition Coupler 21-27mm x 15-21mm. Anything I should be wary of when working with the lead pipe? Do I take the angle grinder to it and then just use the UTC to go to 15mm copper?

As you have worked out original mains supply went to feed cistern (tank) and everything low pressure from there.
Yes feed everything as you go through building.
I'd be trying to get rid of much of old lead as possible.
We use correctly sized lead - loc fittings much neater than a universal philmac.

Exedon said:

As you have worked out original mains supply went to feed cistern (tank) and everything low pressure from there.
Yes feed everything as you go through building.
I'd be trying to get rid of much of old lead as possible.
We use correctly sized lead - loc fittings much neater than a universal philmac.

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Makes sense. I have started laying 32mm MDPE for eventually replacing all the lead pipes in the house, for now though I just wanted to get rid of this weird branching as it's in the way.

I thought of using lead-loc but it's my first time working with lead, so I figured the Philmac one looked more foolproof to use.

Don't use a grinder.
Hacksaw or plastic pipe cutters.
It's soft.

Ensure the lead is really clean and shiny and completely round with no burrs.

dilalio said:

Don't use a grinder.
Hacksaw or plastic pipe cutters.
It's soft.

Click to expand...

Ok will use a hacksaw for this.

Madrab said:

Ensure the lead is really clean and shiny and completely round with no burrs.

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Would that be done the same way as a copper pipe? Deburring cone inside and outside and emery cloth for the outside to make it shiny?

collapse-sued-turkey said:

Would that be done the same way as a copper pipe? Deburring cone inside and outside and emery cloth for the outside to make it shiny?

Click to expand...

Yes - just polish it with a fine paper or even a new green scotch/scouring pad

Make it a junior hacksaw if you have one as it has finer teeth, take your time and cut it nice and square.