Right way to install natural stone waterfall


Sep 23, 2021
Kansas city
I am going to be having a gunite pool installed with a natural stone waterfall where the starting course of boulders will be in the water. I want to ensure my PB and his waterfall contractor know what they are doing before I sign a contract. My biggest concern is ensuring the waterfall does not leak outside the pool. I have watched several pool build youtube videos where a shelf is formed in the gunite for that starter row of boulders, but they never talk about sealing that section. With gunite and mortar being porous how is this section supposed to be sealed to ensure water isn't just continually slowly seeping out of your pool? It is clear that the boulders are set and mortared before the plaster, so it is going to leak without some sort of liner right?

Any advice or resources on how to talk about this intelligently with my PB would be helpful as I can't seem to find a definitive "how to" out there myself.


Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
Bedford, TX

I don't have an answer to your specific question, but I would never, ever recommend having a rock waterfall end in the pool. Pools have waterline tile for a reason.

Real rock in the water will just be a place for things to grow. Some cool looking things are just not practical in the real world.

Let's see if we can get some of our other members to chime in about your question.


Jim R.


Gold Supporter
May 20, 2020
Katy TX
Pool Size
Liquid Chlorine
My waterfall stone sits where the coping would have been. The waterline tile seals against it. I have 1 rock that does touch the water when water level rises (I do not have an overflow in the pool.)
See picture and you can see where the coping stopped, and the stone begins.
I also have this waterfall on a dedicated pump to run as programed regardless of if in Pool or Spa mode.
Pool Waterfall in action.jpg


TFP Expert
Platinum Supporter
May 23, 2015
Tucson, AZ
Pool Size
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
When they create the “concrete pan” to hold the boulders it should be tied into the pools main structure. It needs to be very thick, 8" minimum I would say as natural stone is very dense and heavy. The ground around it also needs to be very well compacted and not subject to shifting, you might ask that the PE that does the engineering drawings has input on that part of the design to ensure the soil and structure holding the boulders doesn't move. they might want to add footers or piers to the pan. All of this is on the PB to do correctly, the waterfall sub has nothing to do with the creation of the pool structure.

Once the pan is in place and cured, it needs to be sealed. My waterfall guys used Laticrete HydroBan concrete sealer to seal the pan before the boulders were placed. They also need to use a waterproof mortar mix for stones. This should all be worked out in a meeting with the waterfall subcontractor PRIOR to the start of any work or, better, before a contract is signed.

One design suggestion - I would highly recommend, from personal experience, that you do not allow them to create levels to waterfall where the water pools in a small basin and then overflows to the next level. It should be all flat surfaces that drain quickly. You will absolutely not want to run the waterfall all the time and small basin pools create the headache of having to run the waterfall many times per day or else the water in the basin loses sanitizer and goes green. I have it on my pool to-do list to fill in all my basins (I have four) with hydraulic cement because I can't stand the fact that they occasionally go green from lack of sanitizer. It's a nuisance and creates more work and pump run time on your pool.

As others have stated, the waterfall should have it's on separate plumbing and pump. You should also use a waterfall pump or, if those are not available, a variable speed pump, on the waterfall plumbing. Mine was built with a single-speed WhisperFlo 1.5HP pump and it's a total energy hog (which is why I hate running it). Waterfall pumps are designed for waterfalls - high volume flow rates at low pressure. Pool pumps are NOT waterfall pumps so don't allow them to put a pool pump on the waterfall plumbing.
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