How do you unblock a drain?
Short answer: start mechanical — a plunger or drain snake — then, if that fails, use the right chemical cleaner for the blockage: a caustic (alkaline) cleaner for grease and organic gunk, or an acid-based cleaner for tougher mineral and hair blockages. This guide shows you how to clear a drain safely and which drain cleaner actually works for South African homes and trade.
A blocked drain is almost always grease, hair, soap and food scraps building up on the pipe wall until water can’t get past. Clear it in the right order and you’ll avoid both a plumber’s call-out and damage to your pipes.
Step 1: try the mechanical fixes first
- Hot water & a plunger. For a sink, remove standing water first, then plunge firmly over the plughole (block the overflow with a wet cloth so you build pressure).
- A drain snake or wire. Feed it in and twist to hook or break up hair and debris, then pull it back out.
- Clean the trap. Under a sink, the U-bend (trap) catches most blockages — put a bucket under it, unscrew it, and clear it out.
If the water still won’t drain, it’s time for a chemical cleaner.
Caustic vs acid drain cleaner: which do you need?
| Type | Best for | Notes |
|---|---|---|
| Caustic (alkaline) — e.g. caustic soda | Grease, fat, food and organic blockages (kitchen sinks). | Dissolves fats and organic matter; the everyday go-to for kitchen drains. |
| Acid (e.g. spirits of salts / hydrochloric) | Stubborn hair, soap scum and mineral blockages (bathroom/shower). | Very powerful — use with extreme care and only when caustic hasn’t worked. |
| Ready-mixed drain cleaner | General blockages, convenience. | Pre-formulated and easier to dose than raw chemicals. |
For most kitchen blockages, reach for a caustic cleaner or a ready-mixed Triple Red Drain Cleaner. For tough bathroom blockages, an acid product like spirits of salts is stronger — but treat it with real respect.
How to use a chemical drain cleaner safely
- Wear gloves and eye protection, and work in a ventilated space.
- NEVER mix products. Don’t combine caustic and acid cleaners, or mix with bleach — the reaction releases dangerous heat and fumes. If one product didn’t work, flush thoroughly with cold water before trying another.
- Add cleaner to the drain, not water to the cleaner, and follow the dosing on the label.
- Give it time to work, then flush with plenty of water.
- Keep well away from children and pets, and store upright and sealed.
Keep drains clear (so you don’t have to do this again)
- Never pour fat or oil down the sink — let it set and bin it.
- Use a drain strainer to catch hair and food scraps.
- Flush kitchen drains with hot water (and an occasional degreaser) to stop grease building up.
- Deal with slow drains early, before they become full blockages.
The best drain cleaners & cleaning chemicals
We stock trade-strength cleaning chemicals for homes and businesses:
- Drain cleaners — the Triple Red Drain Cleaner, caustic soda liquid for grease, and spirits of salts for tough blockages. See all drain cleaners.
- Degreasers — for kitchens, workshops and ongoing maintenance: degreaser range.
- Everyday cleaning — the wider Cleaning & Household range, including trusted Triple Red and Supa Clean products.
Frequently asked questions
What is the best drain cleaner for a blocked drain?
For kitchen drains blocked by grease and food, a caustic (alkaline) cleaner or a ready-mixed drain cleaner works best because it dissolves fats and organic matter. For bathroom drains blocked by hair and soap scum, a stronger acid-based cleaner clears what caustic can’t — but use it with full safety precautions.
What is the difference between caustic and acid drain cleaner?
Caustic (alkaline) cleaners like caustic soda dissolve grease, fat and organic matter and are the go-to for kitchen drains. Acid cleaners such as spirits of salts are more aggressive and better at hair, soap scum and mineral blockages. Never mix the two — combining them causes a dangerous reaction.
Are chemical drain cleaners safe for pipes?
Used correctly and at the recommended dose, drain cleaners are safe for most modern plumbing. The risks come from overdosing, leaving product in too long, or mixing chemicals. If you have old or delicate pipes, try mechanical methods first and follow the product label carefully.
How do you unblock a drain without a plunger?
Try a drain snake or stiff wire to physically clear the blockage, or remove and clean the U-bend trap under a sink. If that doesn’t work, a chemical drain cleaner matched to the blockage — caustic for grease, acid for hair — will usually clear it. Flush well with water afterwards.
Can I mix two drain cleaners to make them stronger?
No — never mix drain cleaners, and never mix them with bleach. Combining caustic and acid products (or either with bleach) releases dangerous heat and toxic fumes. If one product hasn’t worked, flush the drain thoroughly with cold water before trying a different one.
Need trade-strength cleaning chemicals?
Browse our full drain cleaner and cleaning chemical ranges, or contact the Securadeal team for bulk and business orders.
Buying for a business? Our trade guides for cleaning companies & fm and hotels & hospitality cover bulk pricing, VAT invoices and the regulations behind what you need to stock. All industries →