When faced with a blocked soil pipe, it’s easy to feel panicked. That’s because it can quickly become a hygiene issue for your home and your family, and in some cases, it indicates deeper structural drainage problems.

Soil pipes are responsible for carrying foul waste away from your toilets safely into the underground drainage system, so when one is obstructed, you’ll notice slow flushing, nasty odours, gurgling and potentially sewage backing up into the property.

At Express Drainage Surveys, as specialists in CCTV drainage inspections and pinpointing blockages, we wanted to provide a guide on how to identify signs of a blocked soil pipe, some DIY steps to try, and discuss when you need a professional. 

What is a soil pipe and why is it important?

Your soil pipe – sometimes called a soil stack – is the vertical pipe that carries wastewater and sewage from your toilet into the system underground. For most UK homes, you’ll see this pipe running externally along the outside wall, but some properties may have an internal soil stack in a service duct.

We’ve written a lot before about waste pipes, so it’s important to be clear on the differences here:

• Soil pipes carry toilet waste and foul water
• Waste pipes carry water from sinks, baths and showers

Soil pipes are important in ventilation as well, allowing gases to escape before they can build up into a negative pressure in your toilet. 

Many soil pipes in older properties will be made from cast iron, but modern homes are more likely to have uPVC pipes. In truth, both can have their issues, so regardless of pipe material, it’s important to keep it functioning properly. This keeps your property hygienic and free from foul odours.

Common causes of a blocked soil pipe in UK homes

If you’ve got a blocked soil pipe, there will be a definitive reason – or a combination of reasons – and it’s usually down to inappropriate items being flushed down the toilet.

People have been known to find all sorts of weird and wonderful items, but the common stuff includes:

• Wet wipes
• Sanitary products
• Cotton buds
• Nappies
• Excessive amounts of loo roll
• Foreign objects dropped in the toilet

In some cases, the blockage may not be in the soil pipe itself, but in the underground drain it’s connected to. The culprit here can be anything from old pipes that have collapsed to tree root issues and grease build-up.

How do I know if my soil pipe is blocked?

You can keep an eye on these early signs of a blockage, which could help you to avoid more serious consequences:

1. Toilets that flush slowly
2. Water rising higher than normal 
3. Gurgling sounds when flushing
4. Bad odours inside or outside the property
5. Overflow from the external soil stack
6. Backflow into the downstairs toilets or drains
7. An overflowing inspection chamber in the garden

When you notice that multiple fixtures in your home are affected, that’s when you know the problem is actually further down the system rather than something originating in just one toilet.

Can I safely clear a blocked soil pipe myself?

In some cases, maybe, but caution is essential here. Sewage contains harmful bacteria and pathogens, so you should only attempt unblocking a soil pipe if you have heavy-duty protective gear, such as gloves, eye goggles and a way to thoroughly wash off without contaminating your home.

We only recommend DIY methods for the most subtle or minor blockages. If the sewage is overflowing externally or multiple toilets are affected, always contact a professional.

How to clear a blocked soil pipe: A step-by-step guide

• Step 1: Try to locate the exact position of the blockage, as you can save yourself the hassle if you can determine that it’s in the underground drainage pipes. If you can’t locate it, then it’s better to stop here and call in our expert team for CCTV drainage services and drain unblocking.
  
• Step 2: Use a toilet plunger to try to dislodge minor obstructions. You can only do this if there is enough water in the bowl to cover the plunger head, creating a tight seal. You should then pump steadily, rather than aggressively, before trying to flush.
  
• Step 3: You can help shift any remaining organic build-up by mixing warm water and mild detergent down the toilet. Note: this doesn’t shift solid obstructions but gives your pipes a bit of help once the plunger has dislodged things.
  
• Step 4: Don’t use harsh chemical drain cleaners. This is important as it can damage seals and older pipe materials. There is also a splashback concern, putting you and your family at risk.

• Step 5: If you’ve tried the previous steps and things still haven’t resolved themselves, pick up the phone and speak to a local drainage expert and explain the situation with your soil pipe. This is the sure-fire way to restore order to your toilet!

How a CCTV drainage survey identifies the exact cause

If the blockage won’t shift or recurs multiple times, it’s a sign that there might be a bigger problem. In this situation, your repeated plunging won’t solve anything, as you need an actual diagnosis.

CCTV drain surveys provide a clear, internal view of your drainage system – if that’s where the blockage lies – giving you a precise location and cause without any excavation. At Express Drainage Surveys, we use the latest technology to identify cracks, root intrusion, collapses, joint displacement and persistent blockages.

This allows us to recommend the best course of action for your drains depending on the situation. Our full range of services includes everything you could need, but some of our most popular services include:

• CCTV Drain Survey
• Drain Unblocking
• Drain Cleaning
• Concrete in Drains

Facing a blocked soil pipe that isn’t just a minor obstruction? It’s important to act early to protect your home and drainage system. We understand how distressing the situation can be, especially if it impacts your family’s daily life, so call our experts today, and we’ll help provide a professional inspection along with the right solution for your drains.