Step One: Hire a professional. No, not really. You can do this project.
When we moved into our home there was a water feature in our courtyard outside our breakfast area. We loved it when we looked at the house, but since it was late November at over 7400 elevation the water was frozen. We had to trust that it would work. Now that it has thawed (we still freeze some nights, but not all) we found out that although the waterfall pump does work and the water flows; it flows under the rocks rather than over them.
My darling husband decided he wanted to tackle the re-building project himself. Given his sometimes chaotic travel schedule I also got a quick bid from the company working on our outer courtyard. Their bid was $2,000. WOW!! It was only that low because we already had all the rock and other materials and had done the demolition work.
A few Saturday's ago after SugarBear's lacrosse game we got to work rebuilding. SugarBear and LoveBug brought us rocks from all over our property while HoneyBunny and JellyBean brought us small rocks from the pile of rocks that we kept from the previous waterfall.
We used flexible sheeting commonly used as a shower pan liner and an old packing blanket to make the base under the rocks. We then (based on our contractor's free advice) used another layer of the flexible sheeting for each water pool to keep it from leaking into the ground. Silicone caulk worked like glue to keep the liner in place and secure some of the rocks to prevent leaks. Then it was just a matter of fitting the rocks together to create the waterfall effect that we wanted.
It was exhausting work and we all slept well that night. Little by little we have made adjustments to our project to hopefully improve it. Now that it is up and running we all enjoy watching the water during meal times. It was a wonderful family project and I love hearing the boys talk about searching for the right rock and how only they could find the right one.
The view from our breakfast room.