I edited my post. Buildings given by NW/GW don't respect building and population size requirements.Most free buildings do need to respect requirements... it sorta depends on the prereq and how it's applied. It's on a tag by tag rule basis that really should be mapped out again at some point for modders to refer to.
In the modern world, one of the first things you'd do is build a well in a new city to give public access. the Size requirement makes sense for an upgrade but a Pumphouse building or something that would be accessed at the first population seems in order before it would later be upgraded to support a larger community. I wonder how we could require the upgrading...
Wells and cistern are obsolete by Atomic era. Aqueduct and Reservoir are buildable, but needs pop size of 6.
Maybe we need to apply new city GOM tag for one of those?
Code:
<NewCityFree>
<Has>
<GOMType>GOM_TECH</GOMType>
<ID>TECH_X</ID>
</Has>
</NewCityFree>
So solution would be NW, that places Cisterns or Reservoirs in new cities.