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A Guide to Planning Your Underground Drainage Project

When you are going to install an underground drainage system it is important to have an understanding of the materials needed and how the system works. Even though installing underground drainage isn’t the most complicated task in the world, if you get it wrong not only could you cause a huge amount of damage but also find yourself in trouble with your local Building Control Department. Keep reading for BSD’s underground drainage guide.

Underground Drainage Guide

Contact the Building Control Department

The first step to any underground drainage project is making sure that what you want to do is feasible and doesn’t break any laws. If you are planning on undertaking an underground drainage project you need to get in touch with the Building Control Department who will be able to let you know if your project can go ahead.

Learn the Different Types of Drains

Drainage systems in the UK vary significantly depending on when exactly they were installed. There are, however, generally two types of drainage systems.

Foul water - comprises sewage and grey wastewater from WC’s, sinks, baths, kitchen sinks, dishwashers, and washing machines.

Surface water - this deals solely with rainwater. 

If you have an older property, you may find that both surface water and wastewater run into the foul water pipes. This is fine, although a trapped gully is needed to make sure that no foul air escapes. In newer properties, you will have separate foul and surface drainage systems and this is considered standard & best practice.

Get the Right Equipment

When installing underground drainage it is important to make sure you have the right equipment and products. All underground drainage has to be brown in colour that is used specifically for underground drainage. If not, the Building Control Department will make you remove them and start again to ensure you are working to their regulations.

Plan Ahead

Before you start doing any work it is important to have a clear idea of what you need to do. This includes where everything will need to go, how it will connect, and whether it adheres to the building regulations. To ensure everything is pre-planned, it is a good idea to create a diagram that you will be able to constantly refer back to during your project. You should also get the blueprints of the property so you can check that your project won’t interfere with the foundations of the building. 

Prepare and Lay

When you get to the stage where you are ready to dig your trenches, make sure you stick to the building regulations. This means that the top of your pipes needs to be at least 300m deeper than the ground level. Once your trenches are dug up put some granular material in place to form a bed and provide efficient stability for the drainage system. 

You should take the time to make sure all pipes are laid correctly to ensure that both waste and surface water flows properly. It can take time to do this as you must consider the gradients for each pipe. The installation of the pipes is the most difficult part of any underground drainage, which is why if you have not done it before it is best to hire a professional.