We put the water up high so that gravity will help move the water from the tower to your faucet at home when you want to use the water. Waves are created when wind moves across the surface of water. The size, speed and direction of the wave when it reaches the shore is determined by the speed of the wind, the amount of time the wind is blowing in the same direction, and distance over which the wind blows in a constant direction. This is the type of wave I think you were thinking of. Tsunami's are waves created by earthquakes.
Boats can make waves too.
You can make ripple waves in a puddle or lake by throwing a rock into the water. Tides are not the same as waves but can effect waves. Tides are created by the gravitational pull of the moon and sun. This is a very tricky question. Some people would divide all water into fresh water and salt water.