I think the most common one (and imho is to simply tag it `man_made=water_works` and then the most correct) is name of it usually includes the word "desalination" anyway, making it clear. `man_made=desalination_plant` Imho the most correct would be `man_made=desalination_plant` that's been done in 17 places. or maybe `water_works=desalination` could be combined with landuse=industrial e.g. https://www.openstreetmap.org/way/84258438 17 - [man_made=desalination_plant][1] | 2 - [water_works][2] [1]: https://taginfo.openstreetmap.org/tags/man_made=desalination_plant [2]: https://taginfo.openstreetmap.org/keys/water_works#values

I think the most common one (and imho the most correct) is `man_made=desalination_plant` or maybe water_works=desalination `water_works=desalination` could be combined with landuse=industrial e.g. https://www.openstreetmap.org/way/84258438 17 - [man_made=desalination_plant][1] | 2 - [water_works][2] [1]: https://taginfo.openstreetmap.org/tags/man_made=desalination_plant [2]: https://taginfo.openstreetmap.org/keys/water_works#values

I think the most common one (and imho the most correct) is `man_made=desalination_plant` or maybe water_works=desalination could be combined with landuse=industrial e.g. https://www.openstreetmap.org/way/84258438