The first thing you will need to do is create a sturdy foundation for your waterfall to sit on. If you are building it close to the ground you should use concrete blocks as your foundation. If you are building it above ground level, or if you have multiple levels than it would probably be best to use a wood frame. I personally built a 2 level waterfall so I used treated wood to build my foundation. Next you will need to buy a heavy pond liner and put it inside the entire structure. Make sure that the liner is the right size and covers everything and also be sure that it is firmly in place. Next you will need to cut a groove into the wood so that you can hide your return water line. You should also decide which type of lighting you would like to use in your waterfall. At this point you will need to have Styrofoam used on the bottom of a boat dock and cut them in the shape and size that will fit the location you are putting your waterfall in. You will need a mixture of real rocks and boulders and fake rocks and boulders to use in your waterfall. Put the real stones in the places that you would like them to permanently be. The stones around the lip of the waterfall need to be real since they will need to withstand constantly flowing water. Leave room between your boulders to add plants so that your waterfall will look more realistic. The fake boulders will be created in the next step by using a mortar mix.
Once you have the Styrofoam in the place that you want it, wrap it with wire lathe (like the type used to build a chimney). Use a trowel to put S type mortar mix (because it has lower water content) on top of the wire lathe and add layers until you get the exact shape that you want. When you get to the last layer, take your trowel and cut cracks and grooves into the mortar so that it adds an aged and natural look to the “rocks”. Allow about 3 full days for all the layers of mortar to dry. Pick a latex exterior paint that is “stone” colored to paint the entire rock structure you just created. At this point you can add artificial plants and whatever type of lighting suits your taste. Make sure the lights are approved for underwater use so that there is no chance of electrical shock. Now you can turn on your waterfall and see how it looks.
You have now successfully built a swimming pool waterfall, congratulations! Now you can pat yourself on the back and admire how beautiful and calming your new waterfall is. This can be a challenging project but it will bring sophistication to your pool for years to come.