Water that is moving, whether spurting, trickling, cascading or plummeting, is one of the great joys of pond-keeping. There are small contrivances such as spurting frogs, millstones, lions’ heads and even peeing urchins. And then of course there are the larger features requiring the movement of a greater water volume, such as streams, waterfalls, ‘hole-in-the-wall’ falls, cascades and fountains.
In many cases, sound is as important as the visual effect. There is little doubt that the sound of moving water can appear to have a cooling effect on a hot patio, and some even claim that it can mask – or partly mask – the noise of traffic from a busy nearby road. But in order to ‘move’ water, we must invest in a pump or two (or more, if the volume of water to be moved, or the distances involved, are considerable).
The thought of a softly falling waterfall on a sunny day is hugely appealing, but there is an even more fundamental reason why it is a good idea to have a waterfall, fountain, or cascade and that is because it helps to oxygenate the pond. This is essential if the pond is to be its own ecosystem, supporting wildlife, fish and plants. But, if your fountain spurt is barely more than an ooze, or your waterfall no more than a trickle, then your pump is too small. And conversely, if the water emanating from your drilled urn is more like a burst water main, then the pump is too large.
There are dozens of pump styles, makes and sizes available, but the general rule in determining the size of pump required is that it should circulate in one hour a volume of water equivalent to that within the pond system. All pump packs state the circulation volume per hour.
WATERFALLS
A waterfall can be made to spill gently over a shallow sill, or gush in torrents over a high ledge, depending on its design and construction. A good waterfall is a strong statement: it dominates its setting and can easily overwhelm other features. Unfortunately, it is all too easy to miscalculate water flow, and you can readily end up with a torrent of water crashing from a wide ledge into a tiny pond or, conversely, a tiny trickle into a huge pond. Either will look completely incongruous.
There are prefabricated, moulded units available to act as the ‘header’ to a waterfall, and these are simple to install. Ensure that they are level from side to side, and that the lip protrudes sufficiently over the pond – and at a suitable height – to enable a body of water to fall into the pond rather than on surrounding ground. The hosepipe linking the pump to the header pool should be carefully hidden.
Sometimes moulded header units are not the right shape or size, in which case it is possible to make the waterfall of concrete and cover it with flat stone or rock, to make it look natural. Some experts recommend using flexible liners over pre-dug ground, to follow the contours of your waterfall feature but, while this is possible, it certainly is not easy. Making a feature out of concrete is likely to be less fraught, and longer lasting.
If making your own header pool from concrete, use any of the same mix recipes as for the concrete pool, and make sure that the header pool itself is some 15cm (6in) deep. This isn’t deep enough to support fish or plant life, but is deep enough for water to remain within the depression, even during hot weather.
A more natural effect can be created by adding the edging and base stone while the concrete is still damp. Crucially, the edges must be raised and level in the horizontal plane so that water is distributed evenly throughout the basin.
The grotto waterfall
This is one further distinctive type, where water emits from a fairly high header basin, and falls directly in front of some sort of cavern. This cavern can be easily created with concrete and, once established, can be a haven for amphibious wildlife, as well as natural ferns and lichens. Alternatively, by installing the pump and outlet within the recesses of the cavern, and by raising the level of the cavern, you can give the illusion that the water is coming out of the cavern and falling into the pond.
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