How long does a watermaker take to make 100 litres?
Between 0.5 and 5.0 hours, depending on the system. 100 litres is roughly what 4 people use in a day at 25 litres each.
Run time only matters through what it costs. A fast system that draws heavily can use more energy for the same tank than a slow one that sips — the fastest here makes 100 litres in 0.5 hours, but at 19.7 Wh per litre that is still 1,969 Wh.
Where run time does matter on its own is when the power is only there for a window: an engine run, a genset hour, or the middle of a sunny day. Then you want the tank full before the window closes.
Where this is worked through
Other quick answers
Where these numbers come from. Every figure on this page is computed at build time from the comparison table — rated output and rated draw as the manufacturer publishes them, with watt-hours per litre derived as one divided by the other. Nothing is typed in by hand, so nothing here can drift from the table. Where a figure is an assumption rather than a specification it is labelled as one. Methodology · the table.