How to Fix a Blocked Soil Pipe
Last updated: 7 September 2026
Use drain rods, high-pressure jetting, or call a professional drain specialist for persistent blockages.
Overview
A blocked soil pipe can cause serious drainage problems and unpleasant odours. This guide covers diagnosing and clearing a blocked soil pipe.
Step-by-Step Fix
Before beginning any repair, ensure you have isolated power or water supplies. Clear your workspace, gather standard hand tools, and wear appropriate personal protective equipment (PPE).
- First, confirm that the blockage is in the soil pipe by checking which fixtures are affected. If multiple toilets, sinks, and baths are backing up or draining slowly, the blockage is likely in the main soil pipe. If only one fixture is affected, the blockage is probably closer to that fixture.
- Locate the inspection chamber or access point for the soil pipe. This is usually found outside the property, often in the garden or driveway, and is covered by a rectangular or square metal or plastic cover. Remove the cover carefully using a crowbar or screwdriver, taking care not to damage the cover or the surrounding paving.
- Wear appropriate personal protective equipment, including rubber gloves, eye protection, and waterproof clothing, as you will be working with sewage and water. Ensure the area is well-ventilated and that you have a hose pipe nearby for cleaning up afterwards.
- Using a set of drain rods with a suitable attachment, such as a plunger, rubber disc, or screw head, carefully insert the rods into the soil pipe through the inspection chamber. Push the rods forward while rotating them clockwise to work through the blockage. Add additional rods as needed and continue until you feel the blockage break up.
- Once the blockage has been broken up, flush the pipe with water from a hose to clear away any remaining debris. Continue flushing until the water runs clear and drains away freely. Check that all the affected fixtures are now draining properly.
- If drain rods do not clear the blockage, consider hiring a high-pressure water jetting unit. This uses a powerful jet of water to blast through stubborn blockages and clean the internal walls of the pipe. This method is particularly effective for grease and fat blockages.
- If you are unable to clear the blockage or do not feel confident using drain rods or a jetter, call a professional drain specialist. They have access to CCTV inspection cameras and high-powered jetting equipment that can locate and clear even the most stubborn blockages.
- After the blockage is cleared, consider using a biological drain cleaner to break down any remaining organic matter and prevent future blockages. These products are safe for pipes and the environment.
Common Symptoms & Diagnostic Resolutions
Review the common error codes and operating symptoms below to quickly identify the root cause of the fault before ordering replacement parts.
| Symptom / Code | Likely Root Cause | Recommended Resolution |
|---|---|---|
| Multiple drains backing up | Blockage in the main soil pipe | Use drain rods or high-pressure jetting to clear the blockage. If the blockage persists, call a professional drain specialist who can use CCTV to locate the blockage and determine the best method to clear it. |
| Foul smell from drains | Blockage or dry trap causing smells | Clear the blockage and ensure all traps are filled with water. If the smell persists after clearing the blockage, check for a damaged or missing trap seal. |
| Water level in toilet rises when flushed | Partial blockage in the soil pipe | Use a plunger to try to shift the blockage. If this does not work, use drain rods or a plunger on the inspection chamber to clear the blockage. If the water level continues to rise, stop flushing and call a professional. |
| Gurgling sounds from drains | Air trapped by a blockage | This is a warning sign that a blockage is developing. Use a biological drain cleaner or flush the system with hot water to prevent the blockage from worsening. If the gurgling continues, the blockage may be forming and will need to be cleared. |
Frequently Asked Questions
What is a soil pipe?
A soil pipe is the main vertical pipe that carries waste from toilets, bathrooms, and kitchens to the sewer. It is usually larger in diameter than other drain pipes and is often located on the outside of a property or in a service duct. Soil pipes are designed to handle both liquid and solid waste.
Can I unblock a soil pipe myself?
Yes, for simple blockages you can use drain rods or a plunger. However, if the blockage is deep or persistent, you may need to call a professional drain specialist. They have specialist equipment such as CCTV cameras and high-powered jetting units that can clear blockages that are difficult to access.
What is the best way to prevent soil pipe blockages?
The best way to prevent soil pipe blockages is to avoid flushing items that do not break down easily, such as wet wipes, sanitary products, nappies, and excessive toilet paper. Use a drain strainer in sinks to catch food debris and hair. Regularly flush the system with hot water and use a biological drain cleaner to break down organic matter.
How much does it cost to have a soil pipe unblocked professionally?
The cost of having a soil pipe unblocked professionally varies depending on the severity of the blockage and the location of the pipe. On average, you can expect to pay between 100 and 300 pounds for a professional drain specialist to clear a soil pipe blockage. If the blockage requires CCTV inspection or high-pressure jetting, the cost may be higher.