How to Clear a Blocked Drain (And When DIY Stops Working)
24 May 2026 · Plumbers On Duty
Quick answer
For a single slow fixture (basin, sink, shower), DIY works 90% of the time. For two or more slow fixtures, or a backed-up toilet, the blockage is deeper in the main drain — that needs a plumber with rods or a jetter.
Single fixture vs. main-drain blockage (how to tell)
| Symptom | Likely location | Fix |
|---|---|---|
| One basin slow, others fine | Trap under that basin | DIY — clean the trap |
| Shower slow, basin fine | Shower trap or branch | DIY snake |
| Both bathroom basins slow | Branch line | DIY snake or plumber |
| Toilet + bath both slow | Main drain | Plumber |
| Sewage in the shower when you flush | Main drain blocked | Plumber urgently |
| All ground-floor fixtures slow | Main drain or municipal sewer | Plumber, then municipality |
DIY clearing methods (try in order)
1. Hot water + dish soap
Works for grease and soap-based blockages. 2 litres boiling water + 2 tablespoons dish soap, pour over 1–2 minutes.
2. Plunger (cover the overflow first)
A flat cup plunger for basins; a flange plunger for toilets. Cover the overflow hole with a wet cloth so suction is maintained.
3. Remove the trap
Bucket underneath, unscrew the two big plastic nuts on the U-bend, clean it out. 70% of basin blockages are right here.
4. Drain snake
R150 from a hardware shop. Feed in until resistance, twist clockwise, pull back. Reaches 3–5m.
5. Wet-dry vacuum
If you have one, set to liquids, seal it tightly over the drain (with a wet towel as a gasket), and let it pull the blockage out.
What DOESN'T work (don't waste money)
- "Drano" / caustic crystals on a fully blocked drain — they sit on top of standing water and damage your pipes without reaching the blockage
- Vinegar + baking soda — internet myth; the reaction is too weak for real blockages
- Bleach — disinfects, doesn't dissolve
When DIY stops working
Call a plumber when:
- More than one fixture is affected
- You see sewage anywhere it shouldn't be
- The same drain blocks every few months (something is wrong with the pipe)
- The blockage is in a toilet (easy to crack porcelain)
- The blockage is outside in an inspection chamber
What a plumber will use
- Drain rods (R1,200–R2,500 visit): flexible rods screwed together, with attachment heads for different blockages
- High-pressure jetter (R2,500–R4,500): 200-bar water blast that clears roots and scale
- CCTV camera (R1,500–R3,500): identifies collapsed pipes, root intrusion, illegal connections