Make a solar oven, Evaporate the water and then condense it again. It would be pure.
I guess you thought this was a silly answer but it would do what you want.
Think of a ring standing on end.
At the top is a solar oven and the bottom of the loop is in the ground being cooled.
The water you want to reuse would be fed into the oven.
Now add a fan run by a solar cell to circulate the air around the ring.
The evaporated water created at the top would collect at the bottom. The oven doesnt have to boil the water, just heat it. You do not want enough thermal transfer that the bottom heats significantly.
You remove the water to be reused at the bottom.
How much you make would depend on scaling.
This is how the earth makes fresh water.
I guess you thought this was a silly answer but it would do what you want.
Think of a ring standing on end.
At the top is a solar oven and the bottom of the loop is in the ground being cooled.
The water you want to reuse would be fed into the oven.
Now add a fan run by a solar cell to circulate the air around the ring.
The evaporated water created at the top would collect at the bottom. The oven doesnt have to boil the water, just heat it. You do not want enough thermal transfer that the bottom heats significantly.
You remove the water to be reused at the bottom.
How much you make would depend on scaling.
This is how the earth makes fresh water.