What tools for lowering concrete wet room floor?

[Chick21]

I have an existing wet room designed for disabled usage, the floor underneath the lino flooring is concrete with a channel cut in and a drain in the corner.

I want to half the size of it in order to improve circulation on the ground floor and create a compact shower room with a micro basin and wall hung toilet.

The drain currently spans across what I want to be the hallway (indicated by the double line.

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The lowered area would be to the right of this image.

What's the easiest way to do this conversion?

I was looking at purchasing one of these to sink in to the floor, but would require lowering the shower tray area by 24mm and then putting the new drainage channel:
Google "cgi.ebay.co.uk/Marmox-wetroom-tray-wet-room-showerlay-800-x-800-/270702224919?pt=UK_Home_Garden_Bathroom_Shower_Units_PP&var=&hash=item84b77e203f#ht_1652wt_906 "

Would I be able to do it with an SDS drill with a chasing bit?

[stoneyboy]

Chick21,
"What's the easiest way to do this conversion" ---> level the floor and fit an above ground shower tray.
end

[Chick21]

Apologies, I should have mentioned that the current soil pipe is above the current shower drain and hence requires a pump.