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What is the main purpose of a Soil Pipe?

Want to know a little more about what a soil pipe is?

In today’s blog, we’re taking a closer look at soil pipes – including what they are, how they differ from waste pipes, what they are made from and their main purpose.

Within your home, there are specific pipes to remove waste away from your home and, if you’re to maintain them, you need to know the difference between them. Unless you’re a qualified plumber or drainage engineer, knowing your soil pipes from your waste pipes can be easier said than done. So, stick around to find out more.

What is a Soil Pipe?

soil pipe is a pipe that conveys sewage or wastewater reliably, either from the toilet or sink to a soil drain or sewer. They are relatively easy to spot as they run vertically from the underground drainage system to the top of a property, where they reach the roof gutter.

Although any pipe could physically perform this task, the soil pipe – also known as a soil vent pipe – has a specific quality that makes it so useful for carrying soiled waste. It’s of a dimension that allows solid waste to pass and is vented to reduce the risk of nasty odours. It is usually vented high at the top, or close to the top of a building, thanks to soil pipe stacks, and helps to maintain a safe environment. For the reasons behind this, take a look at our blog, why are soil pipes vented?

What are Soil Pipes made of?

Traditionally, a soil pipe was made from cast iron, and some even contained asbestos which would require very careful handling during their maintenance. Though cast iron is a very strong, resilient material, it’s prone to eventual rust.

Most modern soil pipes today are made from UPVC – the leading choice in residential drains for more than four decades. Light in colour and boasting excellent durability and resistance, UPVC soil pipes are arguably the best for your budget too.

How does a soil pipe differ from a waste pipe?

Put simply, soil and waste pipes both carry waste away from our homes to the sewer – and are available to purchase, here at Total Pipeline Systems along with matching fittings. But there are a few distinct differences between them.

A waste pipe usually has a smaller diameter than a soil pipe and carries water away from your sinks, washing machine, bath, shower or any other appliances that use water, rather than soiled waste. Waste pipes can also be narrower as they only needs to carry water and, therefore, don’t require the same venting system as a soil waste pipe.

Where is my soil pipe?

In most modern homes, the soil pipe can easily be identified either above the roof or on side of your home. Older properties which still have cast iron soil pipes usually have them protruding from the rood. You can easily spot a modern plastic soil pipe as it branches out into a tree-like shape.

Why does it matter?

Knowing the difference between a soil pipe and waste pipe will prevent you from flushing materials down the wrong drain. 

Removing waste from toilets through waste pipes is not recommended as this can produce foul smells that can often offend your neighbours or those within a close vicinity! Soil pipes are suitable for bodily waste because they are vented differently to general waste pipes. They are vented through the roof of your home – allowing methane and other dangerous gases to escape into the air without lingering.

How do they work?

The way a soil pipe works is straightforward.

It transports the waste from your bathroom, toilet and sink on the upper floor of your home to the underground drainage system. However, this can be a smelly job which is why you must make sure that you choose vented soil pipes.

Vented soil pipes release any odours into the atmosphere – eliminating the build-up of bad smells. The way these pipes are vented encourages aerobic sewage digestion which simply means that oxygen can enter the system to remove gases, yet prevent anaerobic decomposition which is the breakdown of waste.

The vent also ensures that the drainage system remains at atmospheric pressure. This is vital because when a toilet is flushed or the sink is emptied, if the soil pipe isn’t vented, a partial vacuum would build up behind the wastewater as it travels down the pipe. The result of this? The water in the u-bends of toilets and sinks will burst and allow foul smells and gases to travel up the pipe, and into your home.

However, to further protect your home against leaking sewer gases, we supply universal sink and bath waste traps and overflow waste systems, here at Total Pipes. These make sure that waste material is taken to the soil vent pipe safely.

How to tell if your soil pipe is blocked?

Much like any pipe that carries waste from your home, there is a risk of a blockage occurring – but how do you know if your soil pipe is blocked without calling out a professional?

Although unpleasant to deal with, a blocked soil pipe is pretty easy to recognise as it will often come with a slow draining toilet and an unpleasant lingering aroma coming from the drainage network.

It is generally advised that if a serious blockage has occurred you should seek professional help as there are a lot of technical aspects to unblocking a soil pipe that often require specialist equipment.

Order Soil Pipes from Total Pipes today!

You’ll discover a wide range of soil and waste pipes at Total Pipes, such as push-fit soil pipes and solvent weld soil pipes, pan connectors and universal fittings, including various sizes. Our team has detailed knowledge of the products available, so can help you to find the perfect solution for achieving maximum functionality. We aim to satisfy the demands of all customers, ensuring that we speak in a language that you understand (trying to keep things as simple as possible!).

Should you require any advice or support regarding the soil pipes we have available, don’t hesitate to get in touch with our team of experts. Simply call us on 01254 382 000 or send an email to, and we’ll get back to you.