Why should we conserve water if there is plenty of it in the ocean?

Desalination requires energy, that energy comes from electricity. Electricity is generated by hydro (dam) all suitable locations for dams are used. Coal, this is very dirty technology, think about strip mining and increased carbon emissions. Can come from gas fired generating plants, gas is a non renewable resource, burning it also increases carbon emissions, or nuclear. Fresh drinking water is one of the most precious commodities on this planet, wasting it needlessly is very irresponsible.