types of water feature

pond construction note no.5001

Small ponds so often look wrong. Most people probably don't think that they do - maybe you're a bit surprised at this assertion.

Most garden ponds try to look like a “natural” pond, but as such they are just too small; at typically 6 ft long they are, in the natural order of things, no more than puddles. They would naturally dry up in hot weather, or if fed by a stream would be no more than a bulge in the water-course.

I have come to realise that the “natural” style of pond is what people predominately want, and that most people do not have the room for one of the size I suggest below, so we will look at the different ways to achieve such a pond. However, we will also look at the alternatives, which might actually suit you better.

In a small pond you cannot easily establish the kind of balanced nutrient-cycle that is required. you might say that the answer lies in filtration, and it does, but this only compensates for the fact that the pond is out of balance in the first place. The body of water is too small, the temperature fluctuates too much, the fish population is too large, the plant population probably inadequate and the nutrient levels far too high.

If you look at the photos on the right you will see the other problem, which is one of scale. Aquatic plants are by their nature, vigorous, and will outscale a small pond within a few years. In this pond, which I built for my young boy (see article on Children and Water) I have ignored most of my own arguments for not building a small “natural” pond, except that I have given it a large natural marginal plants area and limited it to three fish. The pond stays clear but only because, even with choosing less vigorous aquatics, it is choked up.

As you will see from the diagram below, a "natural" pond should have gently sloping sides to provide for a soil base inside the liner in which marginals and emergents are planted directly, and also for safety. children and small animals cannot easily climb out of a steep-sided pond. Also the liner is never visible or prone to damage, even if the level drops, as it will, through natural fluctuation caused by evaporation and transpiration (take-up of water by aquatic plant roots, expired out through foliage).

Whilst not every side needs a sloping edge, you can see how this puts a limit on the minimum size that a pond should be. Too small, and you will not achieve sufficient depth. This suggests a minimum size of 4.5 metres, or fourteen foot.

So, we have now established that there are restrictions on the ideal natural pond size, but this is not the only type of water feature we can have. Let's list the different types:

The first we have covered, so let's consider a water feature. this is any type of water that does not try to be a natural pond. Usually it will not contain fish and is designed to display water in a more artistic manner, through a fountain, water sculpture or rill.

At right is a recently rebuilt water feature, also in my own garden. At first glance it too might seem quite natural, but in fact it is far more stylised. It is quite shallow and the main focus is the water (and light) emitting from the old coil. Aquatic plants are quite limited and there are definitely no fish! The emphasis is on a more sculptural aspect. This could equally have been in a formal structure such as a rectangular or “L” shaped pond, or a rill.

A stream garden is a fascinating alternative to a small natural pond and is simply a shallow, moving body of water, often without any main pond or pool to the lowest point.

These can be great where children are present as they are shallow enough to play in (supervised, of course) but they can add a new dynamic to any part of the garden. They must be designed to look like they run through the garden, and on elsewhere. That way they suggest a sense of movement, of journey.

This must have a body of water at the lowest point to be able to operate, which can be a pond or can be a hidden sump tank, the construction of which is a little complicated, but not impossible with due care and attention.

A formal pool is generally of a linear nature and in no way tries to mimic the natural order. Rather it takes it's lead from symmetry, often from surrounding architecture.

In the case illustrated here, there was a clear geometric layout to the garden, as well as the existing linear wall to the rear of the feature, which was at a conflicting angle. A well thought out linear design resolved these conflicting lines and produced a simple result. Problems of geometry are not apparent, which is always a goal of good design.

Formal features have the capacity to create stunning focal points, often of a sculptural dimension.

Formal rills have been around since the dawn of civilization. The first gardens that we know of celebrated and revered water and used rills in geometric designs. The Victorians revived the rill as an integral part of often complex water gardens. In post-war years, however, the rill has been all but forgotten until recent re-inventions at the garden shows have revived an interest.

Rills are exciting, carrying water from one place to another, much as a stream garden does, yet with that hint of deliberate purpose brought about by the artificial container that is the rill. With underwater lighting, there is nothing better or more enticing.

Finally, the lake. beyond the reach of all but the lucky - and wealthy - few, who can resist the allure of a large body of water? But when does a pond become a lake? There are no absolute answers to this. One American definition I read was anything over 65 acres! I don't think that scale quite applies here but over the years, I have worked out the following definition: a lake is any body of water that achieves a depth greater than four metres, at which depth aquatic plants can't grow. Even that definition cuts out many artificial lakes, or ones that have silted up over the years. To achieve that depth, following similar rules of slope degree to that of a natural pond design, does mean that the area has to be over one acre in size; anything less is just (sorry guys) a large pond. Nothing wrong with a large pond, mind.

I hope these definitions will help you in deciding on what type of water feature is right for you!