Backups are always good.
Low temp evaporators seem to be a good way to go.
I would use multiple alternate methods. Filtering sea water with graphene coated sand seems
to be a simple method when there is graphene coated send available.
Making graphene coated sand might not be simpler than using a low-temp evaporator.
So the combined technology of making "ultra sand" and using it to make drinking water
from seawater might be not simpler than a low temp evaporator. Low temp evaporator uses
the well known distillation principle as it happens in nature when rain water is produced.
Ultra sand filter might get saturated with salt and stop working. More development is
necessary. Can an ultra sand filter be revitalized after it gets saturated, and reused or it
gets to be disposable? How much seawater can be filtered with how much ultra sand?
But it works, it just needs a bit of more research and development, and that would be a
technology know-how a seasteader would posses.
There is a way of low temp evaporator/distiller described in the book of Sailing the Farm.
The construction and the use of it is also described. It is tested and proven to work.
I see that vacuum vapor compression method as a version of low-temp evaporator/distiller.
The vacuum vapor compression method was used by the US Navy in 1945 to get drinking
water from sea water. I think it is a well developed and tested method. The Navy method
might involve higher temperatures, so the practical application to make it low temperature might
need a bit development too.
Graphene is a new technology. New technologies are always good to have too.
The practical application of ultras send (graphene coated sand) for the production of drinking
water from sea water, in my opinion, needs a bit of development.
The good news , in my opinion, is , that this can be developed and researched.
I will let you know how far I get.