Responsibility
Who Is Responsible for a Blocked Drain?
Your pipe, Watercare's main, or Auckland Council's stormwater? The boundary decides who pays — and it takes about thirty seconds to work out.
DIY
To unblock a sink, work from the gentlest fix to the strongest: bail out the standing water, plunge with the overflow or second bowl sealed, open the trap's cleaning access over a bucket, flush a greasy pipe with hot water and dish detergent, then feed a sink auger through the plughole. If none of that works, or other fixtures are affected, the blockage is out of reach and it is time to get a blocked kitchen sink looked at properly.
Most blocked sinks are a few centimetres from the plughole, and everything below is safe for a householder to try. The one thing we would keep you away from is drain chemicals while there is standing water in the bowl; the reasons are further down. For a blocked shower drain, a bath or an outside drain, see our guide on how to unblock a drain.
Take five minutes to work out what you are dealing with before you pick up any tool. Bail most of the standing water into a bucket, put on rubber gloves, and check whether anything else in the house is slow. If the dishwasher, the laundry or the outside gully trap is also affected, the blockage is not in the sink, and none of the steps below will reach it.
Two more checks. If anyone has already poured a drain product in, do not plunge or use an auger: read the label and the safety section below first. And if you rent, our guide to blocked drains in rental properties explains who is responsible before you spend anything.
Work through these in order and stop as soon as the water runs freely. Each step reaches a little further down the pipe: the plunger shifts a soft plug in the trap, the cleaning access lets you lift out what has collected in the trap, hot water and detergent loosen a grease coating, and an auger reaches past the trap into the waste pipe.
Use a cup plunger, the flat-rimmed kind made for sinks, rather than a flanged toilet plunger. Leave five to ten centimetres of water in the bowl so the cup is covered. Then seal every other way out: hold a wet cloth hard over the overflow opening, or put the plug in the second bowl of a double sink and have someone press on it. Without that seal the pressure escapes and nothing moves. Press down gently to push the air out, work the plunger firmly up and down ten or fifteen times, then pull it off sharply. A gulp and a swirl means it is moving.
The trap, often called the U-bend, is the curved or bottle-shaped fitting directly under the plughole. It holds a little water to stop drain smells coming up, and it is where most sink blockages end up. Many traps have a screw-off base or a cleaning cap made to be opened by hand. Put a bucket underneath, unscrew it slowly, let the water run out and pull out what is inside with a gloved hand or an old brush. Check the washer is seated, screw it back hand-tight, then run water and watch for drips.
Under the Plumbers, Gasfitters, and Drainlayers Act 2006, removing or disconnecting a trap or waste pipe counts as sanitary plumbing, which is restricted work, and the PGDB's list of jobs householders can do doesn't include traps. Opening a cleaning cap built into the trap is as far as we would go. If clearing it means undoing the trap from the pipe, or the joints are glued, cracked or won't reseal, that is a plumber's job.
If a kitchen sink drains, but slowly, the pipe is probably coated with grease rather than plugged. Squirt a generous amount of dish detergent into the plughole, follow it with a few litres of hot tap water, wait a few minutes and repeat. That softens and moves a thin layer of fat. Use hot rather than boiling water: boiling water poured straight in can soften or distort some plastic waste fittings and seals, and against a full blockage it just sits in the bowl.
It is the most searched home remedy, so here is the straight answer. Baking soda (sodium bicarbonate) and vinegar react to make carbon dioxide, water and a little salt. The fizzing looks busy but is over in seconds and has no real pushing or dissolving power against a plug of fat, food or hair. On a sink that is only slow and a bit smelly it does no harm and can freshen the trap. On a blocked sink it mostly uses up time you could spend on step 5.
A sink auger, also called a drain snake, is a coiled steel cable on a hand-cranked drum, and it is the household tool that reaches past the trap. Feed it into the plughole, or into the trap's cleaning opening, until you feel resistance. Lock the cable, turn the handle to bore into the blockage or hook it, and ease forward. Pull it back slowly over the bucket; it will come out dirty. Don't force it round tight bends, and take care in plastic fittings, which scratch and crack more easily than metal ones.
When a dishwasher leaves water in the bottom, the cause is usually its own filter, not the drain. Take the filter out (most twist and lift out of the floor of the tub), wash the mesh under hot water with a soft brush, and wipe out the hollow it sits in so nothing is blocking the pump. Consumer NZ recommends making filter cleaning a regular habit.
If the filter is clean and it still won't drain, check that the drain hose behind or beside the machine has not been kinked or squashed where the unit was pushed back in. Then look at the sink. In most kitchens the dishwasher discharges into the sink's waste pipe below the bowl, so a blocked sink stops the dishwasher emptying, and water rising in the sink during the pump-out is the giveaway: clear the sink first. A pump that hums but won't empty, or a fault code that keeps coming back, is a job for an appliance technician.
A washing machine pumps its water out fast, into a standpipe behind the machine or over the edge of the laundry tub. If that water overflows the standpipe or fills the tub, the pipe beyond cannot take it at the pump's rate. The usual reason is lint that has collected in the pipe and bound together with detergent residue, sometimes with grease from a kitchen line that joins it further along.
Start with the machine's own lint or pump filter, cleaned the way the manual describes. Then run a sink auger a metre or two down the standpipe to break up what is sitting there. A lint catcher on the end of the discharge hose stops most of it reaching the pipe in future. If the outside gully trap overflows every time the machine empties, the blockage is in the drain outside, and an auger from the laundry won't get to it.
Bathroom basins block with hair, soap and toothpaste rather than fat, and the blockage usually sits right under the plug. Lift out or unscrew the pop-up plug, clean the hair off it, and pull more out of the top of the waste with a barbed plastic drain strip or a bent piece of wire. Run hot water. If it is still slow, plunge with the overflow covered, then try the auger.
A basin that slows down every few weeks is nearly always hair. A cheap plughole hair catcher stops most of it, and a quick pull with a drain strip once a month keeps the waste clear between times.
Most of the harm done while unblocking a sink comes from chemicals used in the wrong order. Never plunge or use an auger after pouring in a caustic or acid drain product: the plunger can push it straight back up at you, and these products cause chemical burns to skin and eyes. Never mix drain products with each other or with bleach, and never pour a second product on top of one that hasn't worked.
For skin, flush straight away with plenty of running water. For eyes, rinse gently with room-temperature water for at least 15 minutes. Don't make anyone vomit. Call the National Poisons Centre on 0800 764 766 (0800 POISON), free and 24/7, and dial 111 if someone is unconscious or having trouble breathing.
Whether any drain product is worth buying in the first place is a separate question, covered in do drain cleaners work?
Stop and call when the sink is still blocked after the plunger, the trap and an auger; when more than one fixture is affected; when the outside gully trap is full; when a drain product is sitting in the sink; or when clearing it would mean taking the trap off. At that point the blockage is past what household tools reach safely, and pushing harder tends to make the job bigger.
A drainlayer or plumber works from the right end, usually the gully or an inspection point outside if the blockage is past the house, with a drain machine or a jetter for set fat. You can get a blocked sink cleared anywhere in Auckland, or request a free estimate first. If the sink keeps blocking every few months, compare what you are seeing with the signs of a blocked drain further down the line, and keep fat and scraps out of it in the meantime: our guide to what not to put down the drain has the short list.
Go to the trap first: open its cleaning cap over a bucket and clear what is inside by hand. If the sink is slow rather than stopped, hot tap water with a good squeeze of dish detergent often shifts a grease coating. After that, a sink auger reaches past the trap. Pumping a wet cloth over a basin plughole with your palm can move a soft blockage, but it is a weak stand-in for a plunger.
Treat the two bowls as one system. Put the plug in one bowl, or have someone press a wet cloth over it, and plunge the other with a few centimetres of water in it, so the pressure goes down the pipe instead of up the other side. If the bowls share a trap, check its cleaning access too. If both sides stay full after that, the blockage is past the trap.
Usually something is: a thin coat of grease, or a ring of hair and soap, narrows the pipe without stopping it. Less often the cause is venting, which shows up as gurgling and slow draining at several fixtures, or a waste pipe laid with too little fall. If cleaning the trap and flushing with hot water and detergent makes no difference, it is worth having someone look.
The law treats removing or disconnecting a trap as sanitary plumbing, which is restricted work under the Plumbers, Gasfitters, and Drainlayers Act 2006, and traps are not on the PGDB's list of jobs a householder can do. Opening a cleaning cap or screw-off bottle that is built into the trap for clearing is as far as we would go. If the trap has to come off the pipe, call a plumber.
Don't plunge, don't use an auger and don't add another product. Keep children and pets away, open a window and leave the sink alone. Check the label for what it says about a sink that has not cleared. When you call someone, tell them the product type and when it went in so they can protect themselves. If any has splashed on skin or in eyes, rinse with plenty of water and call 0800 764 766.
Tell us what the sink, the dishwasher and the gully outside are doing, and we will tell you what it probably is and what it should cost to clear.