Sinks & kitchen drains
Blocked Kitchen Sink Auckland
Most blocked sinks are stuck within arm's reach of the plughole. When yours isn't, the answer is the right tool at the right access point, not another bottle from the supermarket.
Sinks & kitchen drains
Most blocked sinks are stuck within arm's reach of the plughole. When yours isn't, the answer is the right tool at the right access point, not another bottle from the supermarket.
A blocked kitchen sink is usually fat, oil and grease that has cooled and set inside the trap and waste pipe, with food scraps and soap caught in it. If only the sink is slow, the blockage is local and often something you can clear yourself with a plunger or a sink auger. If the dishwasher, the laundry or the outside gully trap is affected too, the blockage is further down the shared drain and needs a drain machine or hydro-jetting from outside.
If it is just the one sink, start with our step-by-step guide on how to unblock a sink yourself. It covers the plunger, the trap, the dishwasher filter and what not to pour in. This page is for when that hasn't worked, or when the clues say the problem is further away.
Kitchen sinks block because of what goes down them far more often than because the pipe has failed. Warm fat and oil from pans and plates go down as liquid, cool within a short distance and cling to the pipe wall. Food scraps, starch, coffee grounds and soap residue then catch on that coating. Over months the bore narrows until one more scrap stops the flow.
Dish detergent helps fat off the plate, but it does not stop that fat settling further along once the water cools, which is why sinks block even in careful households. Watercare's advice is direct: don't pour fats, oils or grease down the sink. Scrape them into your Auckland Council food scraps bin if you have one, or let them cool, collect them in a covered container and put them in the rubbish. The longer list of kitchen culprits is in our guide to what not to put down the drain. A regular dose of drain product does not prevent any of this either; we look at that in do drain cleaners work?
Kitchen and bathroom sinks block for different reasons, so they clear differently. A kitchen sink collects grease and food, which coats the whole pipe and usually sits in the trap or just past it. A bathroom basin collects hair, soap scum and toothpaste, which tangle around the plug and the top of the trap. Basin blockages are usually shallower and easier to reach yourself.
Basins also have an overflow, the small opening under the rim, which matters when you plunge: unless it is covered, the pressure escapes through it. Kitchen sinks have a different quirk. Many are double bowls joined below the plugholes, and many carry the dishwasher hose as well, so one blockage can show up in two or three places at once. Showers, baths and other fixtures are covered in our guide on how to unblock a drain.
Where the blockage sits decides who can clear it and how. If only the sink is slow, it is almost always in the trap or the waste pipe within a metre or two. If the dishwasher or laundry also backs up, it is past the point where those pipes join. If the gully trap outside is full or overflowing, it is in the drain beyond, out of reach from the sink.
| What you see | Where it probably is | Who clears it |
|---|---|---|
| One sink slow, everything else fine | The trap or the sink's own waste pipe | Often you, with a plunger or sink auger |
| Both bowls of a double sink full | Below where the two bowls join | You, plunging with the other bowl sealed; a plumber if that fails |
| Plunging moves water but it never clears | Past the trap, in the pipe through the wall | A plumber or drainlayer with a drain machine |
| Dishwasher or washing machine water comes up in the sink | The shared waste pipe or the drain outside | A drainlayer |
| Gully trap outside full or overflowing | The drain downstream of the gully | A drainlayer, working from outside |
| Wastewater in the street or at the neighbours' too | Possibly the public main | Watercare, (09) 442 2222, option 1 |
In many Auckland houses, older ones especially, the kitchen waste pipe runs out through the wall and discharges into the outside gully trap, the grated dish near the kitchen wall. Lift the grate. If it is empty while the sink is full, the blockage is between the sink and the gully. If it is brimming, the problem is downstream and plunging the sink will not help. If several fixtures are struggling, our guide to the signs of a blocked drain helps narrow it down, and if neighbours are affected too, Watercare want you to call them before a plumber. Our guide to who is responsible explains where your pipe ends and theirs begins.
A dishwasher usually drains through a hose connected to a spigot on the sink waste under the bench, so it empties into the same trap and pipe as the sink. A washing machine pumps into a standpipe or the laundry tub, which often joins the kitchen line or reaches the same gully outside. That shared route means a blocked sink can stop the dishwasher emptying, and a lint-choked laundry line can back up into the kitchen.
The pattern tells you where to look. If the sink drains fine on its own but fills when the dishwasher pumps out, the restriction is past the junction. If the washing machine's pump-out overflows the standpipe or the gully, the laundry line is narrowed, often with lint bound up in grease from the kitchen. A dishwasher that won't empty while the sink runs freely is usually its own filter, a quick fix covered in the DIY guide linked above.
Connecting and disconnecting a dishwasher or washing machine is one of the few plumbing-related jobs the Plumbers, Gasfitters and Drainlayers Board lists as fine for a householder. Work on the traps and waste pipes is not.
Cafes, restaurants and takeaways send far more fat down the drain than a house, which is why food premises use grease traps and why trade waste rules apply. Watercare assesses trade waste against the Auckland Trade Waste Bylaw 2013, and grease traps fall under Building Code clause G13 Foul Water, with G13/AS2 as the acceptable solution. Watercare asks that traps be commercially cleaned regularly.
A grease trap only holds back what reaches it. The lines from the sinks to the trap, and from the trap to the public main, still build up, and a trap overdue for emptying lets fat through into the drain beyond. On a busy kitchen that pattern is better handled with scheduled hydro-jetting than with callouts in the middle of service. Emptying the trap itself is usually a job for a liquid waste contractor; the drainage work is the pipes either side of it.
Grease interceptors and digesters are alternative solutions that need Watercare's approval, and whether a business needs a trade waste agreement depends on how Watercare classifies it. Their guidance on commercial cooking fats sets out what they expect from food businesses.
How it runs
The method is the same as any drain unblocking job: work out where the blockage is first, then clear it from the end that moves the debris away from the house, with the gentlest tool that will do it. On most domestic sinks that is one visit and no digging.
Which fixtures are affected, whether the gully outside is full, and whether any drain product has gone in. That decides where to work from and which gear to bring.
A blockage in the trap or waste pipe is reached from the sink. One past the gully is cleared from outside, through the gully or an inspection point, so fat is moved away from the house rather than back towards it.
A drain machine cuts through a plug of fat and food. Where the whole pipe wall is coated, hydro-jetting strips the coating off instead of boring a hole through it.
A sink line that blocks again within months may have a sag, a poor joint or too little fall. A camera shows which, so you fix the cause once.
The law splits a blocked sink in two. The trap and waste pipes under the sink are sanitary plumbing, which is plumbers' work. The drain outside, from the gully trap to the public connection, is drainlaying. Restricted drainage work is done by PGDB-licensed drainlayers, and you can check anyone's licence on the public register at pgdb.co.nz in under a minute.
Householders can clear a blocked drain themselves, provided they don't alter or repair the inspection or ventilation pipe. Plunging, using a sink auger and cleaning a dishwasher filter are all clearing. Taking a trap off is not, which is where the DIY route ends.
Cost
Clearing a blocked sink is priced on what it takes, not on the sink itself. A blockage in the trap is a short job. One past the gully, a pipe lined with years of set fat or a long commercial line takes more time and heavier equipment. These are the things that move the price, roughly in the order they matter.
| What drives the price | Why it matters |
|---|---|
| Where the blockage is | A trap or a short waste pipe under the sink is quick. A blockage past the gully means setting up outside and working along the drain. |
| Access | A clear cupboard under the sink and a reachable gully keep the job short. A gully buried under pavers, decking or a garden bed adds time before any clearing starts. |
| How much fat is in the line | A fresh plug of food and grease clears with a machine. A pipe lined with years of set fat needs jetting and more time. |
| Home or commercial kitchen | Commercial lines are longer, carry far more fat and are often worked around trading hours. |
| Whether a drain product is in the sink | Caustic or acid sitting in standing water has to be dealt with safely before anyone can work on the pipe, which slows the job down. |
| When you call | After-hours and public holiday callouts carry a higher rate than a booked weekday visit. |
For how drainage pricing works across every kind of job, see our Auckland blocked drain cost guide. You get a realistic range on the phone and a firm price on site before work starts.
A single slow or blocked sink is rarely an emergency. Stop using it, hold off on the dishwasher and the washing machine, and either try the DIY steps or book a normal weekday visit. It becomes urgent when wastewater is coming up somewhere else, such as a shower or floor waste, when the gully outside is overflowing across the section, or when a commercial kitchen cannot trade without its sinks.
In those cases our emergency drainage line runs 24/7. Until help arrives, every tap you run and every load you wash adds water to a pipe that cannot take it, so stopping water use is the most useful thing you can do.
Usually not. A blocked sink holds its own water and nothing is escaping, so it can wait for a booked visit without an after-hours rate. Treat it as urgent if water is rising in a shower, floor waste or other fixture, if the outside gully is overflowing, or if you run a food business that cannot trade without it. Until then, stop using water in the kitchen and laundry.
The dishwasher pump pushes a lot of water into the sink waste in a short time. If the pipe beyond the junction is partly restricted, that surge pulls air through the sink's trap on its way past, and you hear it gurgle. It is an early warning that the shared waste pipe is narrowing, usually with grease, well before the sink blocks outright.
Check the sink first. If it drains slowly too, or water appears in it while the dishwasher pumps out, the shared waste pipe is the problem and the dishwasher is only the symptom. If the sink drains normally, start with the dishwasher's own filter and the hollow it sits in, then make sure the drain hose is not kinked behind the unit. Faults inside the machine are for an appliance technician.
Not on its own. A waste disposal unit grinds food small enough to leave the sink, but the particles can still settle in long or flat runs and mix with fat into a paste. Use plenty of cold water while it runs and for a while after, and keep fat, stringy peelings and coffee grounds out of it. If a sink with one keeps blocking, look at the pipe beyond it.
It depends where the blockage is. The sink, its trap and the waste pipe inside the house are sanitary plumbing, which is plumbers' work. The drain outside, from the gully trap onwards, is drainlaying. Plenty of tradespeople hold both licences. Whoever you use, you can look up their name or licence number on the PGDB public register before the job starts.
Often enough that it never gets close to full, which depends on how much fat the kitchen produces and the size of the trap. Watercare asks food businesses to have grease traps commercially cleaned regularly but does not set one interval for everyone. Keep the service records, check how full it is between visits, and shorten the interval if the lines downstream start slowing.
We cover the whole region. Pick your suburb for local detail.
Tell us what the sink and the gully are doing. We will tell you whether it is a DIY job, and if it isn't, what it should cost.