Show water source in app and on website?

I would not use that option, because it would overload the map. Furthermore I assume that this is a very rare use case.

Nevertheless: The website you linked above offers to download the found drinking water places as GPX, you can import that GPX in Kurviger as overlay and use the drinking water places for planning.

Remark: According to
https://wiki.openstreetmap.org/wiki/DE:Tag:man_made%3Dwater_well
it would be better to focus on nodes which additionally have the tag “drinking_water=yes” - I propose to use an overpass search like

and import them as overlay in Kurviger as already described in other threads:

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