Drainage is a vitally important feature for gardens – but it’s true that not every outdoor space will need it. Considering installing some? Here’s everything you need to know… 

Check your local planning laws

Features such as ditches, streams, or soakaways are all suitable for use in a garden but it’s worth checking out all your local laws and asking the council about what is and isn’t allowed. It’s usually prohibited, for instance, to add drainage water from gardens directly into sewers or storm drains.

If you’re in a situation where water simply has nowhere to go, then it’s worth changing tack and considering growing in raised beds. 

When should you install drainage?

The best time to install drainage is in the later stages of summer – especially if there has been a spell of dry weather. Installation involves porous pipes, which must be buried at roughly 45cm deep – which is why you need dry weather. It’s much more difficult to get right when there has been a lot of rainfall. If you’re attempting this yourself, then it’s important to get the very best premium building supplies to do the job properly (and safely), but if you’re in any doubt – get professionals in to complete the work. 

Why do we need drainage?

It’s important to ensure your garden has the right level of moisture for everything to grow successfully – and also to stop water damage to the ground or property. 

Take a look round the garden after rain. Look for any surface puddling, which can mean that there are compacted layers beneath the surface. A great test to try is to dig a hole about 1 foot deep and pour in some water. If it remains there for hours or days the soil may benefit from installing drainage.

However, don’t just go all in and get it fitted straight away – first of all consider cultivation methods. They might be all that’s required to improve the situation. Try digging or rotovating the beds and adding some organic matter before you opt for other drainage techniques. 

What types of drainage are there?

Simple ditches: This is, as it suggests – a simple technique! All you need to do is dig ditches about 90cm deep and ensure they have sloping sides across the lower end. These should be enough to get rid of excess surface water. You can hire trenching machines to do this – or ask a pro landscaper. 

French ditches: These are constructed by filling a ditch with gravel and topping it with a permeable membrane. This should be enough to keep water from entering. 

Piped drainage: This technique is something that really should only be done by professionals and it requires perforated plastic pipe, which must be laid in trenches on a firm bed of coarse gravel and then topped off with 4 inches of more coarse gravel. It’s a heavy job and should only be attempted by skilled landscapers. 

What problems can occur when installing drainage?

One of the most common is not planning properly and then cutting through pipes and cables. So map out and inspect the land thoroughly before you go ahead. 

Sometimes it’s tricky to lay pipes with enough fall for all the water to drain away properly. In this case, you might want to consider getting the pros in to install either float switches or electric pumps to help out.

Finally, there can be issues with finding a place for water to ‘go’. You can’t simply dump excess water anywhere you like, nor can you let it run through into neighbour’s gardens! One answer to this is to install a pond – which is an eco-friendly way of dealing with the issue and can help encourage wildlife to the garden, too. 


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