Backwashing the pool filter this morning, and having recently watched _Dune_, can't help but wonder what the first Fremen off-world must have thought when they encountered people throwing away gallons of water _just_ to clean some crud off their sand...
(Other than, y'know, crysknife to the face.)
@cerebrate @nyrath
I suspect there is a small amount of algae in the sietch reservoirs; ISTR mention of small fish kept there to eat any sandtrout that manage to get to the water.
I may be conflating things from God Emperor or the Dune Encyclopedia; it's been a while.