Costs of bathroom renovation including minor modifications

but items like the supply lines, drainage, heated towel rail, screed, possibly new electrical installation, pre-wall installation, etc. are missing.

above all, it is unclear how the installation of supply lines and wastewater can be implemented.

Hello dear forum members, I want to renovate the bathroom in my apartment from the 60s. As was common back then, the bathroom is very small (approx. 3.5m²) and (unfortunately) equipped with a mini bathtub-shower combo. I would like to replace this with a shower. Since all connections and drains are on one side, the small size (room depth only 2m) also results in a rather unfavorable configuration, because the toilet and sink are next to each other. You would gain significantly more space for the shower (across the entire width) if the sink could be moved to the opposite side. Of course, this requires major renovations, i.e., drain and water supply lines. I am aware that a bathroom is a considerable cost factor, but what I have been confronted with in terms of prices here in Berlin, where I live, has really taken my breath away. So far, I have contacted three companies, all of which told me to budget 15,000 (!!) euros if I want to avoid surprises. That sounds like an extremely large amount of money to me – the bathroom only measures TxWxH 2x1.70x2.70. I have very little experience with this and wanted to inquire here whether these prices are typical. Many thanks in advance.

the bathroom measures only WxDxH 2x1.70x2.70

First of all, many thanks for the detailed and helpful answers. I am also using other trades in the apartment – you just think that it’s easier to do everything questionable before moving in. Other craftsmen ultimately say that it is mainly due to the current situation in the construction industry – meaning more work than craftsmen results in higher prices. However, I definitely cannot spend 15,000 euros on a (mini) bathroom. Sure, doing it yourself helps. But you either need the skills or the time – preferably both. I also think there is no other option than to go through a portal. I will probably have to give up on relocating the washbasin.