Adding Waterfalls and Streams to your Garden Pond

Basic Design        Noise       Construction      


Waterfalls provide 3 main functions within your pond system. They allow you to have ponds at different levels which means that you can produce a much more natural overall effect than if you just had a large flat pond of the same size. The action of the water falling into the pond below helps to provide a source of oxygen for the fish and waterfalls provide the sound of flowing water that transforms a garden into a haven of tranquility. And of course they look great.

Basic Design

If you are going to have waterfalls in your pond system, they are one of the most important features in your initial design. The position of the waterfall will govern how the pond below it is shaped just under the water flow and the height of the top edge will set the level of the sides for the pond above it. The size of the pump that you use to re circulate the water will also need to be considered, but for more advice see the pumps and filters section.

When you have waterfalls, the pond system must be built from the bottom up. First, you must dig out the general shape of your ponds (shown in brown in the diagram) so that you have an idea where the waterfall is going to be. Then you have to fit your liner for the bottom pond ensuring that it overlaps the waterfall and feeds down into the pond above. That liner is shown in black. Once the bottom liner is in position, the liner for the top pond is fitted, this time overlapping the bottom pond (shown in pink). In that way, there is no path for the water to leak back under the liner and be lost.

The top of the waterfall is a favourite position for birds to bathe so the liner must be protected. In this diagram I have shown a slate in purple. Slate is very good for this as it usually provides a smooth flow of water over it, no matter how much water is flowing. However, anything that can be fixed in position to provide protection for the liner can be used.

The dotted line shows that the surrounding edge of the top pond must be above the top edge of the waterfall. After only a few weeks, algae will accumulate on the surface of the waterfall cover and will be thick enough for the level of the water to rise by about 1cm. If at any time you are not able to monitor your ponds for a few weeks, it is better to leave an extra margin for this rise in level.

It doesn't matter how many ponds you have. Just treat them all like this. Always start from the bottom and work upwards. In my pond system I have 4 levels and the liners have been laid just as explained. however, the appearance of each of my 3 waterfalls is different because I have used a different form of construction.

For this waterfall, the liner was in position long before the waterfall so the only way to build it was to find a slate that could overhang the liner. As I didn't have one that was big enough for the bulk of it to be over the join in the liners, I used 2 slates and set them to overhang each other.

As you can see, a major disadvantage of this method is that the liner is visible from the other side of the pond and as the level drops through evaporation during the summer, it can look quite unsightly.

In order to completely hide the liner, this waterfall was made by using rocks to build a wall in front of the liner so that the water falls down in front of the rocks but that the liner is completely hidden behind them.

This waterfall has a drop of about 30cm so I was concerned about the level of noise. However, the bridge deflects most of the noise down the garden and the smooth flow over the slate reduces it further.

This waterfall was going to be too small to look right with rocks etc so I decided to simply let the water flow "downhill" from one pond to the next by simply tucking the top liner behind a pebble in the bottom pond. However, as I had to protect the liner, I laid about 1" of cement over the top of it. Once the cement had set, I carefully removed the pebble and now the water can fall into the pond from its concrete lip. Within about 4 weeks, the algae growth had masked the cement and now it looks just like a natural water shoot.   Top

Noise

Whichever type of waterfall you decide to create, you need to ensure that the sound of the water splashing down into the pond below is what you want. Ideally, you will be pumping water for 24hrs a day on 365 days of the year. That being the case, you don't want to have a sound that doesn't suit. The general idea is to simulate the sound of a babbling stream with a gentle fall of water. Niagara falls may look nice but it is not really restful and if you have too much water flowing, you can forget any tranquility in the garden. However, you can also have too little water flowing. Remember that a slowly dripping tap has often been used as a form of torture. Too slow a trickle can have a disturbing, if psychological, effect on the bladder. Not something you want to hear through an open bedroom window on a balmy summer's evening. And you can bet that if you don't like the sound, nor will your neighbours.

The positioning of the waterfalls makes a huge difference to the sound in various parts of the garden. Sound is very directional in its travel and the shape of the waterfall can even focus that sound into a more defined direction. For that reason, I have positioned all my waterfalls so that they point away from the house. The combined sound from all three is hardly audible from the house, but as we move down the garden, the sound increases until the full effect is heard at the bench at the bottom of the ponds and from our patio.

There is only one way to get this right, and that is by trial and error. Before you begin your construction in earnest, roughly put your waterfall together and play a hose over it so that the water falls into a bucket positioned beneath the fall. Ensure that flow from the hose it as close as you can get to the flow of your pump. Once the bucket is full and over-flowing, the sound of the waterfall will be similar to the real thing. Listen to the sound from relevant places in your garden and from your neighbours' garden if possible. Don't forget that sounds appear much louder at night when most ambient noise has disappeared, so always check later as well.

If you have to make adjustments at this stage, its far better than doing it later. You can make quite a difference to the sound by varying the width of the waterfall as that changes the relative impact of the water into the pond below. A slight change in the horizontal level of the waterfall stone / slate can also make a subtle change in the sound.   Top

Construction

Once you have decided on the position and shape of your waterfalls, you can begin the construction. First, ensure that the whole area is covered with carpet or other suitable protection for your liner. In the diagram, I have shown that as pink. Note that the carpet and the butyl liner have to go over the sides of the waterfall as well.

Then position the butyl liner. You will need to fold and manipulate the liner but try to get it as smooth as possible where it forms the base of the waterfall. At this point, you need to position your slate and rocks carefully into position (don't puncture the liner) and play your hose onto the slate to establish the best angle for the fall of water that you want. (You'll need to do this again now because the carpet will have slightly modified the position of the slate, and you can't do it later because you'll wash away your cement.) Once you are happy with the position, remove the rocks and slate and dry off the liner.

Next, make sure that your cement is mixed to a state where it is malleable but not runny and spread a layer of cement about 3 to 4 cm thick across the whole of the waterfall base. Then carefully lay the rocks and the slate back into position. The idea here is to make sure that the cement forms a seal between all the rocks and the liner so that the only way that water can get past is where you want it to. ie over your waterfall, rather than seeping around or under the slate. If you intend to have a good flow of water, getting a good seal is less important since you will still get enough water going over the top to give you the effect that you want. However, if you only intend for a gently trickling waterfall, you can't afford to have any water seeping under the slate because it will just "stick" to the liner and you won't even see it. If necessary, add more cement between the rocks but remember that any cement that's above the eventual waterline will be visible, so try to minimise any overspread and try to make it appear as smooth as possible. Eventually, it will become covered in moss and lichens but that can take a long time.

Try not to get too much cement in the pond below the waterfall but don't be too paranoid about it. A little cement might give any fish in the pond a headache for a couple of days but I've never known any long term problems. Any particles in the water will be captured by your filter within a fairly short time anyway.

At this stage, you should have something like the photograph here. Although, if you have more sense that I have, you'll do it at a slightly warmer time of the year. Yes that is ICE. I chose what turned out to be the coldest part of the year for this modification.

Actually, it wasn't as daft as it might seem at first. During late winter, the whole pond system has effectively shut down. So, none of my plants got damaged during the move. My aim was to have everything finished before the spring so that everything is in the correct place before it started to grow. Also, the frog spawning season was not interrupted. This picture was taken in early February and the picture on my home page is the same pond at the end of August in the same year, so I think that it was worth getting cold for a while.    Top

For the next part, please see the Constructing my Ponds pages.