Minimum dimension DIN standard mini wall shower water terrace experiences

Hello everyone and thank you for your time.... We have a problem with the drainage of an outdoor shower on a rooftop terrace. Unfortunately, the builder did not plan for the shower area to be slightly lower on the terrace than the rest and also with its own drain. Thus, the shower water now runs across half the terrace to one of the two drains. I can guide it to another drain with a small rubber wall or a cemented / tiled wall (about 1.20m long)... but unfortunately, it does not flow there by itself... I also do not want to open the tiles and roof insulation to move the shower area downward. Here is my question... Since the property is also to be legally rented to vacationers during our absence, it should be legal and comply with DIN standards or similar... I am referring here to the size, shape, etc., of the element that prevents the water from flowing onto the rest of the terrace or the element/object that leads the water as a barrier to the drain... Is there a minimum size, e.g., 5cm high and 5cm wide or even 90cm and 10cm wide, etc., so that this small wall or let's say drain aid is not legally problematic... keyword tripping hazard! I imagine someone might overlook this threshold, fall, and hold us legally responsible if we do not comply with the standards... I would be very grateful for help and tips.... I think the German legal / factual situation would be the basis! Many thanks! Jochen from Tenerife!

Make yourself a 2.2m long sandbag with a 5cm diameter. Then you are on the safe side. Lie down while showering, then place it at the edge.

I changed my mind while reading the opening post: at first I wanted to give the subtle hint that a picture is worth a thousand words. Then I switched and now ask very astonished how one comes up with the original idea that auf Teneriffa GERMAN industrial standards apply (?)

I changed my mind while reading the opening post: at first I wanted to give the subtle hint that a picture is worth a thousand words. Then I switched and now ask very astonished in return how anyone comes up with the original idea that German industrial standards apply in Tenerife (?)

Morning, of course German industrial standards do not apply in TF, I am only giving general information here and think that Germany is probably stricter than Spain. It is more of a general question about what you would do. Thanks...

Make yourself a 2.2m long sandbag with a diameter of 5cm. Then you are on the safe side. Lie down while showering, then place it on the edge.

Thanks. Good idea, but leaves room for errors with guests... But an alternative....

but it leaves room for errors when it comes to guests.

That is probably true. Possibly that is not enough for your concern for guests, but the liability aspect should be taken care of with it.
Sometimes I get the impression that we create so much safety that people lose their instinct and attention for everyday dangerous situations. This has become so absurd that people fall into an abyss while taking selfies.