huckster: desalination plants require a huge amount of power to be able to run,
No. A desalination plant is just a tank or two with a clear sloping lid and a dark bottom. Under heat from the sun, the water evaporates and condenses on the lid (as drinkable water) and drains into a gutter. No power is required for this. The water needs to be pumped into the tank(s) and around the water network, as with any system. The pumping could be with solar powered electric pumps, hand pumps or solar pumps. One square meter of surface area on the tank will produce a couple of litres of water each day and it's not impossible to have small systems for one house or one farm.
Many of the problems come with organising the infrastructure for a system that operates over anything more than a small local area. Many African governments are not good at organising anything outside their capital city. Somaila, where many of the refugees are coming from, is worse than the rest.
There is actually a "spare" refugee camp in the same area as many of the refugees. It curently has water and accommodation but the local government has not yet given the go-ahead for it to be used.