Actually one can take out renewable energy produced at the desalination facility or anywhere close to it out of equation. The drinkable water can be viewed by

Actually one can take out renewable energy produced at the desalination facility or anywhere close to it out of equation. The drinkable water can be viewed by itself as "salty water + stored energy". If you produce it at any time where electricity demand is low/or production exceeds demand you store energy already produced, be it by nuclear or renewable power plants. And then you can build the pumped-hydroelectric power station where it makes sense, not being limited to the coast line/big city being close. Even if one lives on a desert coast there may be times where it makes more sense to purify and store water from say flash floods than desalinate it from the sea. IMHO your idea may work if we think about some isolated location not attached to the grid and without some power plant running 24/7. No idea at which scale pumped hydroelectric starts to be viable.