What Is the Difference Between Foul Water Drainage and Surface Water Drainage?

Every property has its own network of seemingly complicated drains and pipes that allow wastewater and rainwater to be safely carried away from the building.

If you’re experiencing trouble with excess water or waste removal on your property, then you’ll need to start investigating the system that’s already in place to find the problem.

For that reason, it’s important to know the difference between the major components of the drainage and sewerage systems that buildings are connected to. The two most important aspects that need consideration are foul water drainage and surface water drainage.

There are important distinctions between the two. In this article, we take a look at the difference between foul water drainage and surface water drainage.

What Is Foul Water Drainage?

Foul water is any waste or wastewater that needs to be treated before it can be safely released into the environment. Foul water is the waste produced from your bathroom, shower, or kitchen sink, and it’s in no way clean or environmentally friendly.

To dispose of this wastewater or sewage, buildings have a network of pipes that are collectively known as a foul water drainage system. In towns and cities, these pipes ordinarily connect buildings to the local foul water drains, which form part of the wider sewerage systems.

In this case, foul water is drained directly from the home to the sewers, from where it makes its way to a larger sewage treatment plant. The foul water is treated and then disposed of. Public sewers often dispose of treated wastewater into local watercourses or into the sea.

Septic Tanks, Sewage Treatment Plants and Foul Water

In many places, properties might not have access to the public sewer systems. In this case, there needs to be an on-site sewage treatment plant or a more basic septic tank installed on the property. Foul water then drains from the property into the septic tank or sewage treatment plant, where it is treated using naturally occurring bacteria.

The foul water is broken down and then released safely into the local environment or into local streams or watercourses, once it’s safe to do so. Increasingly septic tanks and sewage treatment plants are being installed on properties to lower sewerage bills or to become more environmentally friendly and self-sufficient.

What Is Surface Water Drainage?

Surface water is very different to foul water. In most properties, there’s a separate drainage system installed to deal with it.

Surface water is water that has collected outside, on driveways or in gardens. Surface water forms after heavy rainfall or from rising deposits of water beneath the ground. As surface water has collected naturally, usually from rainwater, it’s considered to already be clean (it’s not sewage).

Surface water drainage systems are in place to allow this clean surface water to be carried away from a property. Again, in places where there’s public sewerage, surface water drains direct water towards public pipes and properties are charged by their local water provider for the service.

As surface water is clean, it can be sent directly into local watercourses or into the sea. It does not need to be treated, as sewage needs to be.

Surface Water Drainage Systems

Some properties don’t have access to public sewers and need their own systems in place to dispose of surface water. This is important, because excess surface water that builds up is a health and safety hazard – it can cause flooding and could even cause structural problems to a property over time.

Off-mains surface water drainage systems can be established to drain clean water directly into nearby watercourses or into a specially built soakaway

As you can see, foul water and surface water are two very different things. Foul water can’t be drained into a surface water drainage system, as it could contaminate the local environment. Surface water needs its own drainage system that allows clean runoff to be put back into the local environment without needing to go through sewage treatment plants or septic tanks.

Contact OMDI Today for Your Free Quote

At OMDI, we’re well practised at designing and installing off-mains surface water drainage systems, alongside septic tanks and sewage treatment plants. We can help to survey existing systems and identify solutions, before creating the ideal drainage system for your home or commercial property.

If you need a new surface water drainage system, then our expert team are ready to help you. Contact OMDI today for your free quote.