The waterfall / Water feature.
I decided that I wanted a water fall as my water feature. Below you can see the location where I prepared the site for the water fall.

Firstly I used some bricks and soil to elevate the area where I wanted the water feature.
Secondly I placed black building plastic on top of the prepared area to stop water from leaking through into the soil.
Then I mixed concrete and added some brown oxide to it to stain the concrete brown as i wanted a natural colour. I poured the concrete on top of the black plastic and shaped it with my hands.

For the base of the feature I decided to use slate.
I then bought and gathered a few big rocks which I wanted to use to form the structure of the waterfall. I also added a little water plant to water feature just for the fun of it.
You can see what the feature looks like at this point by looking to the image on your right.

Lastly I waterproofed some of the areas where I thought I would be loosing water and I also added some smaller river stones for effect.