What Is A French Drain?

Understanding the type – or different types – of drains you have on your property is super important if you want to better maintain it. We know it can often be confusing to get to grips with this topic, which is why we’re exploring a specific type of drain this month at Express Drainage Surveys.

French drains, which are actually named after an American named Henry French, are popular drains for properties. In this guide to French drains, you’ll find out how they work, where they’re best placed, how to install your own French drain and much more. 

Let’s begin with a closer look at how this drain type works and how it varies from traditional drains you find as standard on most properties.

How does a French drain work?

Some alternative names for a French drain may give you more of a clue as to how these drains work; gravel drain and trench drain are synonyms for this style. It essentially involves a relatively shallow trench dug into the ground, into which a perforated pipe is placed. The trench is then backfilled with gravel over the top of the pipe.

The perforation in the pipework allows water from around the property to easily enter and be carried away safely to avoid pooling or oversaturating the ground. The gravel over the top is the ideal filtration material, catching any debris but allowing easy passage for rainwater – especially in conditions where floodwater can gather. 

With the pipe in the trench gently sloped, it should quickly and effectively lead water away from an area without too much hassle. Any debris that does manage to find a way through the gravel will likely be stopped at the pipe since the perforation holes should be relatively small.

The endpoint for a French drain can be shared with your normal drains and storm drains or its own soakaway pit if in more rural areas. The latter allows for the water to be gradually filtered into the surrounding soil. If you happen to be close to a natural watercourse such as a stream or river, these are also good destinations for your French drain to be directed towards.

What are the benefits of a French drain?

While French drains aren’t an absolute essential for most properties, they do come with plenty of benefits if you’re faced with certain conditions in the way your land lies. Here are just seven benefits of a French drain to consider:

• They can help prevent flooding – By diverting excess water away from any part of your property prone to flooding, you can keep things dry and avoid a total washout.
  
• They reduce soil erosion – If you leave any kind of water to run off your property naturally, there is a risk of soil erosion. French drains help to divert that water in a controlled manner.
  
• They reduce damage to foundations – Your foundations can come under a lot of pressure if surrounded by waterlogging. Channelling the water with a French drain can prevent cracking and structural damage.
  
• They keep your lawn healthy – If your lawn gets waterlogged when there’s too much rain, it can lead to boggy conditions, but a simple French drain could help remove any excess easily.
  
• They’re pretty cost-effective – Faced with many of the issues above? Then a French drain can help, and it doesn’t cost as much as some other drainage solutions.
  
• They’re easy to maintain – Aside from the occasional check every once in a while to prevent any blockages, you don’t have to do a lot to maintain a French drain, saving you time and money.

Where should a French drain be positioned?

The 19th-century judge and farmer, Henry French, first introduced French drains as a way to channel water away from his land where waterlogging was prevalent or where surface water gathered in excessive amounts. So while they may not be the standard drain we find on properties in the UK, they do have their uses in certain areas.

There are several instances where a French drain can help if positioned correctly, including:

• Where flooding occurs: If you have patches of land that are more prone to flooding when there is heavy rain, a French drain could help to quickly divert this water before it reaches your property. The size of the pipe in place will impact what capacity the system has, so while useful, it may not prevent flooding if the rainfall is overly intense within a short period of time.
  
• Where surface water pools: Sometimes the surrounding land can become so saturated by water that it begins to pool. While not as urgent as flooding, standing water can become an issue, particularly if you’re unsure where the water originates from. A French drain can help to redirect water from saturated soil, preventing your ground from becoming boggy.
  
• Where hydrostatic pressure is placed on structures: If you have a basement or you know that your retaining water is being put under pressure by soil that is holding too much water, you can install a French drain to alleviate this. This is a good idea if you’re worried about the integrity of your property when it rains and need a way to draw out excess moisture.

Can I install a French drain on my property?

Given all of the benefits we’ve outlined above, you might be hoping to dive right into installing your own French drain. But wait!

While yes, you technically can install a French drain on your property with ease, you should seek some expert advice before grabbing your spade and bags of gravel and heading out into the garden. There are a number of things you have to keep in mind when planning a French drain, including:

How deep will the trench be?

If you’re looking to keep water away from your foundations, this is especially important as it won’t help if the trench isn’t at the right depth.

How far will the trench run?

The distance from your property is another crucial element, as it can’t be too close to the building itself if you want to avoid compromising its structural integrity.

Is a French drain the solution?

While they do have their benefits, sometimes the water issues you’re faced with on your property might not be solved with a French drain. If your regular drains aren’t performing at their best, for example, then getting them fixed and maintained could be a much better solution. 

Don’t just assume that you need a French drain if you find your normal drains get overwhelmed by rain. This could just be a sign that there is a blockage or damage within your drain that requires attention.

Why choose Express Drainage Surveys?

Are you exploring the topic of French drains because you think that your property needs them? Why not have a professional CCTV drain survey carried out first? Our state-of-the-art equipment can help to quickly establish whether your drains are simply in need of cleaning or repairs to save you the time and hassle of having to install French drains around your property.

We also offer a variety of other drainage services to help you keep your drains flowing healthily so that an extreme downpour doesn’t cause you misery. This includes no-dig drain repairs, drain maintenance and drain jetting for properties up and down the country no matter how large or complex.

Contact our expert team today to discuss your drainage requirements and we’ll be more than happy to find the right solution for a cost-effective result on your property where disruption comes at an absolute minimum.