Blocked drains are one of the most common plumbing complaints for homes and businesses across Cape Town. Knowing what causes blocked drains is the first step to preventing them, sparing you the mess, the odours and the repair bill that come with a serious blockage. Most blockages build up slowly over weeks or months, so a little awareness goes a long way towards keeping your pipes flowing freely.
The most common causes of blocked drains
Nearly every blockage we clear comes down to one of a handful of culprits:
- Fats, oils and grease (FOG): Poured down a kitchen sink, hot fat looks harmless, but it cools and hardens inside the pipe, trapping food scraps until the drain narrows and clogs. The City of Cape Town’s wastewater by-law actually prohibits discharging fats and oils into the sewer system for this reason.
- Wet wipes and sanitary items: So-called “flushable” wipes, nappies, cotton buds and sanitary products do not break down like toilet paper. They snag and bind together, and are one of the leading causes of blocked sewer drains.
- Hair and soap scum: In showers and basins, hair binds with soap and grease to form a stubborn matted plug just below the plughole.
- Tree roots: Roots are drawn to the moisture inside pipes and force their way in through tiny cracks and joints, where they expand and catch debris. Learn more about how tree roots affect your pipes.
- Mineral build-up and scale: Hard water leaves a scale that gradually narrows the bore of older metal pipes.
- Collapsed or poorly laid pipes: Pipes that have sagged, cracked or been badly installed create low points where waste settles and blocks.
- Sewer main problems: Sometimes the blockage is not on your property at all. A clogged or damaged municipal sewer main can cause waste to back up into the pipes serving your home.
Early warning signs of a blocked drain
Catching a blockage early is far cheaper than dealing with an overflow. Watch for water that drains slowly, a gurgling sound from the plughole or toilet, unpleasant odours rising from the drain, or more than one fixture backing up at the same time. If a problem keeps returning after you clear it, there is usually a deeper cause such as roots or a collapsed pipe that needs professional attention.
How to prevent blocked drains
Prevention is mostly about what you keep out of the system. Let fat and oil cool, then scrape it into the bin rather than washing it down the sink. Fit strainers over plugholes to catch hair and food scraps. Stick to the “three Ps” rule for toilets: only pee, poo and (toilet) paper. If you have large trees near your drain line, have the pipes inspected periodically for root intrusion. For a deeper clean, a periodic high-pressure drain cleaning clears build-up before it becomes a blockage. It also pays to know the dos and don’ts of using drain cleaners, as the wrong chemical can damage your pipes.
When to call a professional
A plunger or a careful dose of an approved cleaner will handle a minor blockage, but repeated blockages, sewage smells, or waste backing up into the house point to something more serious. At that stage a CCTV inspection and professional jetting are the safest way to find and fix the real cause. If you are unsure what chemicals are used to unblock drains, or you simply want it sorted properly, our drain clearing services in Cape Town can locate the blockage and clear it without damaging your pipework. For persistent issues, our blocked drain solutions cover everything from one-off clearing to long-term maintenance.
In short, what causes blocked drains usually comes down to fat, foreign objects, hair, tree roots, scale or ageing pipes. Understanding these causes, and keeping the worst offenders out of your drains, is the easiest way to keep your system clear and avoid an expensive emergency.
