Garden drainage is important when it comes to creating a landscaped garden. Some gardens are well drained and do not need extra garden or lawn drainage.
Making sure your garden has appropriate drainage is a first step particularly when you want a healthy and growing garden. Having professionally added drainage will also make sure the hard landscaping features in your garden are properly embedded and not subject to water damage.
How to know if a garden needs better drainage?
Wet winter weather will show how good or bad the natural drainage is. Patches of water on the surface are the most common signs of problems. To check how well the land drains, dig a hole about 600mm (24 inch) deep and 300mm (12 inch) square, then fill it half full of water. Leave it for 24 hours in which time it should empty on well-drained soil. On very wet land, the hole may actually fill.
What causes poor drainage?
Of course, drainage problems need not be caused by any human activity, the soil may by its nature (e.g. clay soils) be water retentive or, if it is low lying, be affected by the natural water table of the area.
On new housing estates it is often caused by compacted soil as a result of builders diggers and dumpers etc driving over garden areas before fencing goes up. This combined with the mixing of sub-soil and topsoil when all the trenches and foundations were excavated often leads to a heavy, wet plot, with very little top soil sometimes only an inch thick.
In cases where new estates have been built on old arable land that has been cultivated annually for centuries, a "plough pan" may have developed. This is an impervious layer of more compact soil just below the maximum ploughing depth, caused by years of polishing by the sole of the plough.
Back to Landscaping
On clay and other water retentive soils, the flow of water through the soil is very slow, this can be exacerbated if the contours of the land form depressions in which the surface water can collect.
On land which has a very shallow water table, not much can be done to avoid water logging after heavy rain as the water table can rise to the surface of the land or actually above it, in this latter case a pond will naturally form. For lawns that are too low we can use a lift pump which will move water up hill to a suitable drainage system.