A grease-clogged kitchen drain is cleaned properly by hydro jetting the kitchen branch, often after an auger opens flow. Snaking alone punches a hole through the grease and leaves most of it on the pipe wall, so the line re-clogs within months. At home, keep fats out of the sink, clean the trap, and use hot water and enzyme products for maintenance only.
- Fats, oils and grease (FOG) cool, stick to the pipe wall and harden in layers, narrowing the kitchen line over months or years.
- The typical clog point is not the sink trap but a horizontal run or fitting where the line cools, often in a basement ceiling or wall.
- Jetting cleans the full wall; augering only opens a channel through the grease.
- Hot water and dish soap move grease further down the line, where it re-solidifies, rather than removing it.
- Wiping pans before washing is the single most effective habit for a clear kitchen line.
01 /How does grease clog a kitchen drain?
Grease clogs a kitchen drain by cooling and sticking to the pipe wall in layers. Liquid fat from cooking flows down with hot water, then cools as it travels. It coats the pipe, especially at the top and sides of horizontal runs, and each new layer catches food particles and soap. Over time the coating hardens into a waxy, soap-like mass that can close most of the pipe.
The chemistry matters. Fats can react with calcium and other minerals in water to form hard, soap-like deposits, which is one reason grease buildup in hard-water regions can be tougher to remove. It also explains why grease deposits are often firmer than people expect when they finally see them on a camera.
| Location | Why grease collects there | Access |
|---|---|---|
| Sink trap and trap arm | First cool-down point; food solids settle | Under the sink |
| Horizontal branch in a wall or ceiling | Longest run with slow flow; pipe cools | Cleanout on the branch, or through the trap arm |
| Where the kitchen branch joins the stack | Flow changes direction | Stack cleanout |
| Building drain downstream of the kitchen | Grease that passed the branch cools further | Main cleanout |
| Long runs in unheated or cold spaces | Pipe is colder in winter | Varies |
02 /Why does snaking a grease line not last?
Snaking a grease line does not last because the auger opens a narrow channel through the grease and leaves the coating on the wall. Flow returns, but the pipe is still mostly closed, and the next pan of fat or a batch of rice sticks to the remaining grease and closes the channel again. A kitchen line that is snaked every few months is a line that needs jetting.
For the broader comparison of augering and jetting, see pipe cleaning methods compared.
03 /How does a pro clean a grease-clogged kitchen line?
- Identify the access point
The operator looks for a cleanout on the kitchen branch. Without one, the line is accessed by removing the trap and working through the trap arm, or from a downstream cleanout.
- Open flow
If the sink is full of standing water, a small auger opens the line so water drains before jetting.
- Jet the branch
A small-diameter hose with a spinning or penetrating nozzle is run up and down the branch. For 1.5 to 2 inch kitchen lines, pressures commonly sit around 1,500 to 3,000 psi on a small jetter.
- Flush with hot water
Warm water carries loosened grease through the stack while it is still soft.
- Check the building drain
Grease removed from the branch often lodges further down. A good operator checks or jets the building drain if the branch empties into a long horizontal run.
- Camera if the problem recurs
A sag or poor slope in the branch makes grease settle faster. Camera footage shows whether a repair would help.
04 /What can you do yourself for a slow kitchen drain?
- Check the disposal and trap first. Many slow kitchen sinks are a blocked trap or a jammed disposal outlet, not the line.
- Clean the trap. With a bucket underneath, loosen the slip nuts and clear the trap and trap arm by hand.
- Run a small hand auger with a bulb head through the trap arm. Expect grey fat on the cable.
- Flush with hot tap water for a few minutes while the line is open. This moves softened grease along; it does not remove the coating.
- Stop if the sink backs up into the other side of a double sink or a nearby fixture: the clog is downstream, and repeated DIY augering may only shift it.
Taking the trap apart is the one home step that reliably removes grease rather than moving it. The full procedure, including double sinks, disposals and a dishwasher that will not drain, is in cleaning the pipes under a sink.
Chemical drain openers are not recommended for grease lines; see chemical drain cleaners for why. Enzyme products are a better maintenance tool; see enzyme drain cleaners.
05 /How do you keep a kitchen drain free of grease?
| Habit | Why it works |
|---|---|
| Wipe pans and plates with paper towel before washing | Removes most fat before it reaches water |
| Collect cooking fat in a container once cool | Keeps bulk fat out of the drain entirely |
| Use a sink strainer | Keeps food solids from catching on grease |
| Do not rely on the garbage disposal for fatty scraps | Grinding does not remove fat; it only makes smaller pieces |
| Avoid pouring rice, pasta, coffee grounds and eggshells down | They bind with grease into dense plugs |
| Run hot water after washing | Carries fat further before it cools; a help, not a cure |
Many Canadian municipalities ask residents to put cooled fats in the green bin or garbage rather than down the drain, because grease also blocks municipal sewers. Check your city's guidance on how to dispose of fats, oils and grease.
Commercial kitchens do at the building scale what wiping pans does at home: a grease interceptor holds wastewater long enough for fats to separate before they reach the sewer. Houses do not normally have one. If you run a food business from home or are fitting out a commercial kitchen, municipal sewer-use rules may require an interceptor and a pump-out schedule, so check with your city before plumbing the kitchen.
For a chronic kitchen line, set a jetting interval from experience: if the line clogged 18 months after the last jetting, schedule the next at around 12 months. See how often to clean drain pipes.
06 /Does the pipe material change how a grease line is cleaned?
Yes. In ABS or PVC, grease sits on a smooth wall and jets off readily. In old cast iron or galvanized steel, grease bonds into tuberculation and pits, so descaling may be needed as well as jetting. In condo and apartment kitchen stacks, grease accumulates across many floors at once and is cleaned as a building system.
- Plastic kitchen lines: jetting alone is usually enough. See ABS and PVC pipe cleaning.
- Cast iron or galvanized: jetting plus light descaling. See cast iron drain pipe cleaning.
- Multi-storey kitchen stacks: see condo stack cleaning.
07 /What does kitchen line cleaning cost?
| Job | Typical quoted range |
|---|---|
| Kitchen sink augered from the trap | $150 to $350 |
| Kitchen branch jetted | $300 to $650 |
| Branch jetted plus building drain jetted | $500 to $1,000 |
| Camera inspection of the kitchen branch | $200 to $400 |
Check your situation with the Pipe Method Matcher or request quotes that specify jetting rather than augering.
FAQQuestions people ask
Does boiling water dissolve grease in pipes?
Boiling water can soften grease near the drain opening, but the grease re-solidifies further down the line as the water cools. It moves the problem rather than removing it, and boiling water held in a blocked plastic trap can stress the pipe. Hot tap water for routine flushing is the safer habit.
Is hydro jetting worth it for a kitchen drain?
For a kitchen line that has clogged more than once, jetting is usually worth it because it removes the grease coating that augering leaves behind. For a single clog in a trap, augering or trap cleaning is enough.
Can a garbage disposal cause grease clogs?
A disposal does not create grease, but it sends more food solids into the line, and those solids bind with grease into denser plugs. Fatty scraps should go in the green bin or garbage rather than the disposal.
Why does my kitchen sink drain slowly but the bathroom is fine?
The kitchen has its own branch line that carries most of the house's grease. A slow kitchen sink with normal bathrooms points to a clog in the kitchen branch or trap, not the main sewer.
Do enzyme cleaners work on kitchen grease?
Enzyme and bacterial products can slowly break down thin grease films and reduce odour when used regularly on an open drain. They will not clear a heavy grease clog; mechanical cleaning is needed first.
How often should a kitchen drain be jetted?
Most households never need scheduled jetting if fats are kept out of the sink. Heavy-cooking households or lines with poor slope may need jetting every one to three years, with the interval set by how quickly the line slowed down after the last cleaning.
NETWORKGo deeper across the HAUSE Sewer network
Fats, oils and grease: how FOG builds up in sewer lines and how to stop it
How fats, oils and grease (FOG) build up in sewer lines, why hot water and soap fail, how sewer cleaners remove grease, and kitchen habits that prevent it.
SewerJetting.caJetting grease lines: how to actually remove fats, oils and grease
Jetting grease lines explained: why FOG hardens in drains, why snaking a grease clog fails, nozzle and hot water choices, and keeping the line clear.
DrainAugering.caHow to snake a sink drain from the trap arm, not the plughole
How to snake a sink drain: pull the P-trap, feed 1/4-inch cable into the trap arm, get it down the tee, and handle double basins and garbage disposals.