Quick Answer

Most blocked drains — kitchen, bathroom, or laundry — can be cleared in 15–30 minutes using a plunger, baking soda and vinegar, or a drain snake, without any chemicals. Kitchen drains block with grease and food scraps; bathroom drains block with hair and soap. If multiple drains are blocked or there’s a gurgling sound, you likely have a main sewer blockage — call a licensed plumber immediately.

A plumber using a plunger to clear a blocked kitchen sink drain in an Australian home
The humble plunger fixes most drain blockages in minutes — the key is creating a tight seal around the drain and using firm, rapid strokes rather than slow pressure.

Blocked drains are one of the most common household plumbing problems in Melbourne, particularly in older homes in Dandenong, Narre Warren, and Berwick where cast iron pipes are gradually being replaced with PVC. Whether it’s a slow-draining sink, a bath that won’t empty, or a blocked laundry drain, most blockages can be cleared without calling a plumber.

Common Causes by Location

Drain Location Main Cause Secondary Cause Best Fix
Kitchen sink Grease and fat build-up Food scraps, coffee grounds Plunger + hot water; baking soda method
Bathroom basin Hair and soap scum Toothpaste build-up Remove and clean drain cover; drain snake
Shower/bath Hair clumps and soap scum Shampoo residue Drain hair catcher; drain snake
Laundry tub Lint, detergent build-up Fabric softener residue Clean strainer; plunger
Toilet Flushed non-flushables Excess toilet paper Toilet plunger; closet auger
Outside drain Leaf litter, debris Tree root intrusion Clear manually; call plumber for roots

Method 1: The Plunger (Try This First)

A plunger works by creating pressure changes that dislodge blockages. Use a cup plunger for sinks and baths, and a flange plunger (with the extension piece) for toilets.

A plumber demonstrating proper plunger technique on a bathroom basin drain, creating a tight seal with the cup plunger over the drain opening
Cover the overflow opening (in basins and baths) with a wet cloth before plunging — without sealing the overflow, you’ll lose all the pressure through it instead of pushing it down the drain.
  1. Remove the drain cover or plug.
  2. Cover the overflow opening with a wet cloth — this seals the system so pressure builds properly.
  3. Add enough water to cover the plunger cup.
  4. Place the plunger firmly over the drain and push down to seal.
  5. Use rapid, firm strokes — 10–15 pumps — then pull sharply upward.
  6. Repeat 3–4 cycles. Run hot water to test.
Pro tip: Petroleum jelly around the rim of the plunger cup creates a better seal on worn or uneven drain surrounds. Smear a thin layer before plunging.

Method 2: Baking Soda and Boiling Water

This method works well for grease-based kitchen blockages and mild soap build-up. It’s safe for all pipe types including PVC and cast iron.

  1. Pour half a cup of baking soda into the drain.
  2. Follow with half a cup of white vinegar.
  3. Cover the drain with a cloth and wait 30 minutes — the fizzing reaction breaks down grease and soap.
  4. Flush with a full kettle of boiling water.
  5. Repeat if needed.
Safety warning: Never pour boiling water into PVC drain pipes immediately after chemical drain cleaners — the combination of heat and chemicals can soften and warp PVC. Let pipes cool for 30 minutes first. Boiling water alone on clean PVC is fine for older Melbourne homes.

Method 3: Drain Snake (Blocked Shower or Tub)

A hand drain snake (also called a drain auger) is the most effective tool for hair blockages in shower and bath drains. Available at Bunnings or Reece Plumbing for $15–$40.

A plumber feeding a flexible drain snake cable into a blocked shower drain, rotating the handle to work it through the blockage
Insert the drain snake cable slowly, rotating as you feed it in — forcing it causes kinking. When you feel resistance, that’s the blockage; rotate to grab it, then pull back to remove it.
  1. Remove the drain cover (usually snaps off or has a single screw).
  2. Insert the snake cable into the drain, rotating the handle clockwise as you push.
  3. When you feel resistance, rotate to engage the clog — hair usually wraps around the auger tip.
  4. Pull back carefully, bringing the blockage out with the snake.
  5. Run hot water to test, and install a hair catcher to prevent recurrence.

Method 4: Clean the P-Trap (Kitchen Sink)

The P-trap is the curved section of pipe beneath the kitchen sink. This is where grease, food particles, and debris accumulate. Cleaning it is straightforward and takes about 20 minutes.

  1. Place a bucket under the P-trap.
  2. Unscrew the slip nuts on both ends of the curved pipe by hand (usually no tools needed on modern PVC).
  3. Remove the P-trap and clean out the blockage into the bucket.
  4. Use an old bottle brush to clean the inside of the trap.
  5. Reinstall firmly and hand-tighten — do not overtighten or you’ll crack the plastic.
  6. Run water to test for leaks.

When to Call a Licensed Plumber

Some drain blockages are beyond DIY. Call a licensed plumber immediately if:

  • Multiple drains in the house are slow or blocked at the same time — this indicates a main sewer blockage
  • You hear gurgling sounds from other drains when you flush the toilet
  • There’s sewage backup from a floor drain or toilet
  • The blockage is in an exterior drain or sewer inspection opening
  • You’ve tried all DIY methods and the drain is still blocked
  • There’s a strong sewer smell throughout the house
Safety warning: Never use chemical drain cleaners if the drain is completely blocked — the chemicals will pool in the drain and can splash back and cause severe chemical burns when you use a plunger or snake. Chemical cleaners are for slow drains, not full blockages.

Preventing Blocked Drains

Location Prevention Method Cost
Shower & bath Silicone hair catcher drain cover $5–$15
Kitchen sink Sink strainer basket; never pour oil or fat down drain $5–$20
All drains Monthly hot water flush; bi-annual baking soda treatment $0
Kitchen sink Wipe greasy pans with paper before washing $0
Laundry Clean lint filter on washing machine; use liquid detergent $0

Top 10 Tips and Gotchas

  1. Never pour fat or oil down the drain. Melbourne’s cold nights solidify grease in pipes within metres of the sink. Collect in a jar and bin it.
  2. Hair catchers prevent 90% of bathroom drain blockages. A $5 silicone catcher is the cheapest plumbing maintenance item in the house.
  3. Don’t use Draino or caustic drain cleaners on older cast iron pipes. They can accelerate corrosion. Mechanical methods are always safer.
  4. The baking soda and vinegar reaction is fizzing, not eating the clog. The value is in the agitation and the hot water flush that follows, not the chemistry.
  5. Older Melbourne homes (pre-1980) often have clay or cast iron sewer lines. Tree root intrusion is common — if you get repeated blockages in the same drain, get a CCTV drain inspection.
  6. Don’t overtighten P-trap slip nuts. Finger tight + one quarter turn is enough. Over-tightening cracks the plastic threads.
  7. Coffee grounds block drains fast. Always bin them, never wash them down the sink.
  8. A gurgling toilet when you run the basin = partial main blockage. Call a plumber before it becomes a full blockage and sewage backflow.
  9. Check the laundry drain strainer monthly. Washing machine lint can silently accumulate until there’s a flood.
  10. CCTV drain inspection costs $200–$350 and can diagnose root intrusion. Worth it if you have repeated blockages in the same location.
A safety expert in hi-vis orange vest pointing at a clogged shower drain covered with hair and soap scum, demonstrating what causes bathroom drain blockages
A hair-clogged shower drain is the leading cause of bathroom flooding — a $5 silicone hair catcher eliminates this problem entirely and should be in every Melbourne shower.

Local Melbourne Resources

  • Reece Plumbing — Drain snakes, plungers, pipe thread tape, P-traps. Locations in Dandenong, Frankston, Narre Warren.
  • Bunnings — Hair catchers, drain snakes, P-traps, baking soda. Stores in Cranbourne, Berwick, Pakenham.
  • VBA Find a Practitioner — Verify your plumber is licensed for any main drain or sewer work.
  • SewerSmart — CCTV drain inspections and high-pressure jetting for stubborn blockages in Melbourne’s south-east.
  • Mitre 10 — Plumbing supplies including drain snakes and pipe cleaning tools.

FAQ

Can I use boiling water to unblock a drain?

Yes, for grease-based kitchen blockages, boiling water is effective and safe for cast iron and metal pipes. For PVC pipes (common in Melbourne homes built after 1980), use very hot tap water rather than boiling — PVC begins to soften at 60°C and boiling water (100°C) can distort joints over time. Boiling water works best as a follow-up to baking soda and vinegar, not as a standalone method.

Why does my drain keep blocking in the same spot?

Repeated blockages in the same drain — especially in older Melbourne homes — often indicate tree root intrusion into clay or cast iron sewer pipes. Tree roots enter through pipe joints and grow into a mass that catches everything passing by. A CCTV drain inspection ($200–$350) will confirm root intrusion, and the plumber can then clear it with high-pressure jetting or recommend pipe relining.

Is it safe to use chemical drain cleaners?

Caustic drain cleaners (sodium hydroxide based) are effective but should only be used on slow-draining, partially blocked drains — never on a completely blocked drain. They can damage older chrome and brass fittings, accelerate corrosion in cast iron pipes, and create dangerous splashback if you plunge after using them. Enzymatic drain cleaners are gentler and safer for regular maintenance.

How much does a plumber charge to unblock a drain?

In Melbourne, a plumber charges approximately $150–$250 to unblock a simple sink or shower drain, including call-out fee ($80–$120) and 30–60 minutes of labour. If high-pressure jetting is required (for main sewer blockages or root intrusion), expect $300–$600. Emergency call-outs outside business hours cost $200–$400+ just for the call-out.

What should I do if sewage is backing up into my bath or floor drain?

Stop using all water immediately and call a licensed plumber as an emergency. Sewage backup indicates a complete main drain or sewer blockage, and continued water use will cause sewage to overflow into your home. Don’t use the toilet, sinks, or shower until the blockage is cleared. This is not a DIY situation.