Quick answer
Kitchen sink blockages are almost always fat, oil and grease building up downstream. Warm fat pours away as a liquid, then cools and sets on the pipe wall a metre or two along, catching food debris until the bore closes. Caustic soda treats the symptom and eventually damages older pipe; high-pressure jetting removes the deposit itself, which is why one lasts and the other does not.
Common causes
- Fat, oil and grease congealing on the pipe wall downstream of the trap
- Food debris caught in the fat deposit and building a plug
- Old galvanised pipework whose rough internal surface collects build-up quickly
- Dishwasher discharging into the same branch and adding starch and grease
- Insufficient fall on the waste run so water moves too slowly to scour the pipe
- Coffee grounds and rice, both of which swell and pack solid
What you can do now
- 1Never pour fats or cooking oil down the drain — wipe pans out with paper first
- 2Run hot water with a squirt of dish soap after every wash to keep the run scoured
- 3Clean the trap under the sink yourself with a bucket underneath; it is often the whole problem
- 4Avoid repeated caustic soda in older galvanised pipes, which it corrodes
- 5Fit a sink strainer and empty it into the bin rather than rinsing it through
When to call a professional
If the sink blocks more than twice a month, book high-pressure jet cleaning rather than paying for repeated unblocking. Jetting strips the fat deposit off the pipe wall and restores the full bore, which chemical treatment cannot do. If it blocks again soon after jetting, ask for a CCTV inspection — that pattern usually means a bellied section or a damaged pipe holding waste.
Typical cost in Johannesburg
Jet clean R950–R1,400
Indicative ranges only. We provide written, itemised quotes before any work.
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