Water is a polar molecule and as such is attracted to a static charge.
By placing a charge near a stream of fresh water we can observe this attraction:
Repeating this experiment with sea water shows similar results, so although salt water is more conductive it is still equally attracted to a charge:
We can raise the surface of a body of water by placing a static charge above it, we can observe the water making a mound underneath.
This is a logical and practical way to explain and demonstrate the tides.