....
The reverse osmosis water maker (admittedly not a new one) on my boat
makes about 1 gph using 5 amps at 12V, so this is about 60 WH/gal.
....

My Spectra makes 8 gph at 8 amps. That makes R/O a full order a
magnitude more efficient in energy terms than the distiller. Of
course, the price of the first gallon of purified water is ~$100 for
the distiller and ~$5k for the Spectra at retail...

-- Tom.