Water and you

The most ordinary way to create a water surface is the normal shader. Since water has no color you give it the color of your environment and you give it some reflection. A little more complex - and longer to render of course - is the Freznel Water shader, where you can sat a wavy reflection. The problem is that your water surface still is absolutely flat, there are no ripples and waves.

As suggested by Gerrit in this thread there is a more advanced way to produce convincing water. To do that we use a greyscale picture for the bump map, two of those can be found in the link. Apply the bump image in the texture mapping dialog and make it entirely transparent, bump it and add reflection.

Along with the bump we need reflection, so drag the slider to the right. Remember that we need both, reflection and bump.

As you can see in the screenshot I am using the normal shader for the water material. You could even add the Freznel water shader here, but the change is in my opinion hardly visible and not worth the render time.