Love it or loathe it, blurred water can look great in the right situation so it is always worth a try.
For those who are new to the technique, here are 10 tips to get you started in turning even small cascades can look like raging torrents.
Time Of Day
Waterfalls are a favourite landscape subject and early morning or late afternoon on an overcast day is the perfect time to photograph them using this technique. Bright sun stops you using slow shutter speeds and the contrast can be horrendous.
Switching to shutter-priority so you can control the length of the time the shutter is open for makes this technique easier so take a camera out you can do this with. DSLRs are an obvious choice but if you want to use a smaller bodied camera, take a look at a high-end compact or Micro Four Thirds System such as the Olympus OM-D
As you're using slow shutter speeds you need to use a tripod, self-timer or a remote cable release. Using the camera's mirror lock-up can also help with this.
A polariser as well as a neutral density filter is handy for cutting down the amount of light reaching the camera sensor, thus allowing even slower shutter speeds.
The slower the speed you choose the more blur there will be. Try a speed of 1/8sec to 1/15sec but if this doesn't work, change the shutter speed and take the shot again.
Volume, Flow And Distance
There is no right or wrong speed for this as this changes depending on how much blur you want, the volume of water (large amounts need shorter shutter speeds), the speed of flow (slower flows need slower shutter speeds) and the distance between the camera and water (shorter the distance the faster the shutter speed needs to be).
Take care when metering water as the large areas of light tones can fool the meter into underexposing, making the picture look dark. It's always worth bracketing, perhaps shooting at plus and minus one stop.
Take Two Shots
A slow shutter speed will add blur to anything that moves so if grass or plants surround the waterfall these could end up blurred too. To combat this, you can take two shots: one with a slow shutter speed to capture the waterfall and one on a faster shutter speed to capture the surroundings. You then combine both images later during post production.
How To Shoot
To create impact, fill the frame with the waterfall. Taking a low angle will also make the waterfall more dominating. Shooting straight on will allow you to capture water patterns.
Away From Waterfalls
This same technique can be applied to wave imagery. You can create lava-style flows of water by choosing a slow shutter speed. Simply mount your camera on a tripod and choose an area where the water is crashing against rocks so the shape of it changes.