Main goal of the design was to minimize costs of reconstruction while making both apartments comfortable and functional.
Both apartments have completely independent water discharge systems as you wanted.
New walls are suggested to be constructed as light brick walls with layer of plaster board at both sides, total thickness of 12 cm. Also it is suggested to cover existing walls with plaster boars as well to get same wall thickness as new walls.
Apartment 1 has complete net area of 30.61 sqm and consists of living room that is composed as a unique space with kitchen, small anteroom that separates living area from comfortable bedroom and bathroom. Mirror on the anteroom wall makes impression of wider space.
In the bathroom, besides water closet, sink and shower, there is a separate closet for washing machine, cleaning supplies and also hidden water heater which is connected to the kitchen as well. Bedroom is equipped with 160x200cm bed and built in wardrobe closet which is planned to be custom made for optimal use of space.
Apartment 2 has net area of 29,79 sqm. It is also equipped with living area, kitchen, proper bedroom and bathroom. Kitchen communicates with living area but it is possible to occasionally detach by closing sliding doors.
Decor is simple taking into account that these apartments are for rent and that people who will live here will take in some of their own touch.
If you need explanation for any part of the project, I'm at your disposal.