When I teach my photo workshops students often ask is there a right or wrong way to capture moving water. My response is “it depends.” The bigger question is what type of water will best contribute to the overall mood and atmosphere of the image? If I am shooting a tranquil calm scene, then most likely I will want my water slow and silky. If I am shooting a kayaker paddling off a waterfall, then this adrenaline shot requires water droplets frozen in the air for the right effect.
But what do you do if it is in the middle of the day under sunny skies. Even with your ISO at 100 and aperture set to F22, you still can’t get exposures 1 second or longer. You could add a polarizer which will help block out another stop or so of light, but still not slow enough. The filter I use to accomplish this is the Singh-Ray Vari-ND. This filter fits on 77mm lenses, and can block from 2-8 stops of light. This enables me to shoot very long exposures in the middle of the day, even 30 seconds!
Super slow exposures result in ‘cotton water’, while exposures closer to a second will have some stream detail. The decision is yours, but photograph water that adds to the feel and mood of your image. The best shots have design elements that compliment each other, not work against one another.