5 Common Causes of Blocked Drains & How to Fix Them
A blocked drain can quickly turn from a minor nuisance into a major headache, especially in London’s older homes. Whether it’s a slow-draining sink or a gurgling toilet, understanding what clogs your pipes is the first step to preventing future backups. In this article, we’ll cover the five most common causes of blocked drains in London houses, share simple DIY fixes, and explain when it’s time to call a professional for a drain unblocking service.
Hair & Soap Scum Build-Up
If you live alone or have a small household, it might surprise you how quickly hair accumulates in shower drains. Over time, hair strands bind with soap residue to form a sticky mass.
DIY Fix:
Use a simple drain snake or a bent wire coat hanger to remove visible hair clumps.
Pour a mixture of 1 cup of baking soda and 1 cup of vinegar down the drain to dissolve soap residue. Let it fizz for 15 minutes, then flush with hot water.
When to Call a Pro:
If hair build-up is far down the pipe and snaking doesn’t help.
When multiple drains in your home are slow, this could indicate a deeper blockage.
Grease & Food Debris (Kitchen Sinks)
Pouring cooking oil or food scraps down the sink is a surefire way to clog kitchen drains. As grease cools, it solidifies and sticks to the inner walls of pipes, trapping bits of food.
DIY Fix:
Avoid pouring grease—let oil cool in a container, then throw it in the bin.
Use a mesh drain strainer to catch food particles.
Try a commercial enzyme cleaner once a month to break down organic matter.
When to Call a Pro:
If you hear gurgling sounds or see water backing up from multiple outlets.
When your DIY attempts (chemical or mechanical) haven’t cleared the clog within 24 hours.
Tree Roots in External Sewer Lines
In many London gardens, older clay or cast-iron drainpipes meet tree roots seeking moisture. Roots can crack or collapse pipes, leading to deep blockages that no DIY hack can reach.
DIY Fix:
Limited. You might clear superficial blockages with a high-pressure hose, but this rarely solves root infiltration.
When to Call a Pro:
Always. A drain unblocking service equipped with CCTV inspection and hydro-jetting is required to locate the root intrusion, remove the encroaching roots, and often reline or replace the damaged pipe.
Soap & Bath Bomb Residue
Luxury soap bars and bath bombs contain oils, butters, and fragrances that don’t fully dissolve. Over time, residue can coat the inside of your bathroom drain, narrowing the flow path.
DIY Fix:
Flush the drain weekly with hot water and 1 cup of vinegar to dissolve mild buildup.
Use a drain strainer to catch larger soap chunks before they go down the drain.
When to Call a Pro:
If you notice foul odours or standing water, even after hot-water flushes.
When your bathroom drain becomes completely blocked, professional removal and pipe cleaning are safer than chemical cleaners, which can damage older fixtures.
Foreign Objects & Small Items
Accidents happen—jewellery, hairpins, children’s toys, even dental floss can slip down sinks or toilets and lodge deep in the U-bend. Once lodged, they trap debris that accumulates around them.
DIY Fix:
Carefully remove the U-bend trap and shake out any caught debris or small objects (be prepared for water!).
Reassemble the trap under your sink, ensuring all seals are tight.
When to Call a Pro:
If you don’t feel comfortable dismantling your pipes (risk of leaks).
If the foreign object is deeper inside your drain line beyond the U-bend, only a professional drain camera inspection can locate and dislodge it safely.
DIY vs. Professional Drain Unblocking Service
If you’re tackling small hacks like snaking hair or running a vinegar flush, you can often clear minor clogs yourself. But here’s when you need to call a professional:
Multiple fixtures are affected (e.g., both bathroom and kitchen drains).
Foul, musty odours indicate sewer gases backing up.
Visible pipe damage (cracks, root intrusion) needs CCTV diagnosis.
Recurring blockages that return within days.
Our drain unblocking service in London uses high-pressure hydro-jetting and CCTV cameras to pinpoint and clear blockages, ensuring your pipes stay clean for months. We also offer a follow-up inspection to confirm everything is flowing freely.
Conclusion & Next Steps
Blocked drains can quickly disrupt your daily routine. By identifying the cause—hair, grease, roots, soap, or foreign objects—you can decide when to DIY and when to call in the experts. If you’re in London and need fast, reliable help, contact Parallel Plumbing Solutions for a comprehensive drain unblocking service.