What Causes Blocked Drains?
I’m Sam — and Roman Rod isn’t just a business to me, it’s my family legacy.
Blocked drains are most commonly caused by a build-up of grease, wipes, hair and debris, though structural damage and environmental factors can also restrict water flow through pipelines. While some blockages form quickly, many develop gradually over time as materials accumulate inside pipework, eventually leading to slow drainage, unpleasant odours or complete obstruction. Let’s take a more in-depth look into this serious situation.
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The Most Common Causes of Blocked Drains
Grease, Fat and Oil Build-Up
One of the leading causes of blocked drains in both homes and commercial kitchens is the disposal of fats, oils and grease down sinks. While these substances slide down the plughole as liquids, they quickly cool and solidify inside pipes, clinging to the inner walls. Over time, this sticky residue traps food particles and other debris, forming stubborn blockages that restrict water flow. The worst that can happen is the formation of a fatberg – a large, solid, waxy mass formed of a combination of fats, oils and grease which mixes with other non-biodegradable items like flushed wetwipes, nappies – even dental floss – that grow and clog the sewer system.
Wet Wipes and Sanitary Products
Unlike toilet paper, wet wipes, sanitary towels and similar products do not break down easily in water. Even those labelled as “flushable” can accumulate in pipework and cause significant obstructions. These materials often combine with grease and other waste, creating dense blockages (the aforementioned fatbergs) that are difficult to remove without professional equipment.
Hair and Soap Residue
In bathrooms, hair is a major contributor to drain issues. It binds with soap residue to form clumps that collect in plugholes and pipes. Soap can also leave behind a hard, chalky deposit known as soap scum, which narrows the internal diameter of pipes and encourages further build-up.
Structural Causes of Drain Blockages
Collapsed or Cracked Pipes
Physical damage to drainage systems can severely restrict water flow. Collapsed or cracked pipes may result from external pressure, corrosion or wear and tear. These issues not only cause blockages but can also lead to leaks and long-term property damage if left unresolved.
Misaligned Drain Joints
Drain systems are made up of multiple pipe sections joined together. Over time, these joints can shift due to ground movement or poor installation. Misaligned joints create small gaps or ledges where debris can catch and accumulate, eventually leading to a blockage.
Ageing Drainage Systems
Older drainage systems are more susceptible to blockages due to material degradation and outdated construction methods. Pipes may become rough or uneven internally, making it easier for waste to stick and build up over time.
Environmental Causes of Drain Problems
Heavy Rainfall and Flooding
Periods of intense rainfall can overwhelm drainage systems, particularly if they are already partially blocked. Excess water can force debris further into pipes or cause backflow issues, increasing the risk of a full blockage.
Leaves and Outdoor Debris
External drains, gutters and downpipes are vulnerable to becoming blocked by natural debris such as leaves, twigs and dirt. These materials can collect in large quantities, especially during the autumn, and obstruct the flow of water through outdoor drainage systems, leaving your property at risk of flooding.
Ground Movement
Changes in the ground, such as subsidence or shifting soil, can affect underground pipework. This movement may lead to cracks, misalignment or partial collapse, all of which contribute to drainage problems.
How Blockages Develop Over Time
In most cases drain blockages don’t occur suddenly, but build up gradually over time.
A key factor in the drain blocking process is biofilm – a slimy, sticky and often smelly layer of microorganisms like bacteria, fungi and algae that attaches to the inner surfaces of pipes.
This nasty gelatinous coating thrives on organic debris, trapping fat, hair and other particles, slowly reducing the pipe diameter and eventually completely blocking it, cutting off the water flow.
This unhealthy situation is usually heralded with persistent odours, slow drainage and gurgling noises.
Left untreated, these issues can escalate into more serious and costly problems.
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To discuss a service with Sam
How to Prevent Drain Blockages
Household Habits to Avoid
Preventing blocked drains often comes down to adopting some simple everyday habits. Avoid pouring grease, fat or oil down the sink, and dispose of wipes, sanitary products and other non-degradable items in the bin rather than the toilet. Using sink strainers can also help catch food scraps and hair before they enter the drainage system.
Routine Maintenance
Regular cleaning and maintenance can significantly reduce the risk of blockages. Flushing drains with hot water and appropriate cleaning products helps to break down grease and remove minor build-ups. Periodic professional drain cleaning can also keep pipes clear and functioning efficiently.
When to Book a Drain Inspection
If you notice persistent slow drainage, unpleasant smells or recurring blockages, it may be time to book a professional drain inspection.
Modern techniques such as CCTV surveys allow specialists to identify the exact cause and location of a problem, ensuring it can be resolved quickly and effectively before it worsen.
Need help with a blocked drain? Roman Rod has been serving homeowners and commercial properties in Bath, Somerset, and Wiltshire, earning 5-star reviews, for over 40 years.
You can count on us for:
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We offer fast, reliable drain unblocking, CCTV drain surveys, and drain repairs with no hidden costs and no call-out fees. Get a free quote today or call us on 01225 332 181.