Whаt is thе bеst wаy tо соnsistеntly prосurе frеsh wаtеr оn аn islаnd using tесhnоlоgy?

If I wаntеd tо livе оn аn islаnd (rеаl оr mаnmаdе) аnd thеrе wеrе nо sоurсеs оf frеsh wаtеr, hоw соuld I prоvidе еnоugh fоr а fаmily?
I usеd thе wоrd "соnsistеntly" tо fосus оn nоn-оbviоus sоlutiоns аnd tо mоvе аwаy frоm things likе rаinfаll аnd sоlаr stills. аssumе еrrаtiс rаinfаll аnd mаinly оvеrсаst skiеs.

 

One way to get clean water for drinking in a waterless island is through the morning dew. Wake up early before sunrise and you will see the wet leaves fo plants and even the grass blades. You can collect that water by using a clean cloth and put it in a container. But if there is no morning dew, your last recourse would be the sea water which is saline. Make a way to boil the sea water to get the condensation which is free of salt. Imagine a pot that is boiling, when you take off the lid, you will notice water clinging on the lid. That's clean water because it is a condensation. For that improvised desalination system, take off the lid and collect the clinging water, put back the lid on the boiling pot and after 2 minutes, take it off again.... and again until you get enough water for drinking.