Grease Clogged Kitchen Drain: How to Clear It and Keep It Clear

Grease clogs are different from hair or debris clogs — they build up slowly on the pipe walls and narrow the drain from the inside over months or years, rather than forming a single discrete blockage. That difference affects both how you clear them and why the same kitchen drain keeps clogging despite repeated fixing.

How to Unclog a Kitchen Drain Full of Grease

For a mild grease slowdown (drain is slow, not completely blocked):

1. Boil water and let it cool slightly — use the hottest tap water, or water that’s been boiled and cooled to 160–180°F (not boiling if you have PVC pipes, which can soften around 140°F; very hot tap water is safe for all pipe types)
2. Add 2–3 tablespoons of dish soap to the drain, then pour the hot water in slowly
3. Wait 5 minutes for the soap to work on the grease
4. Flush with more hot water for 2 minutes
5. Repeat once if the drain is still slow

Dish soap is a degreaser — it emulsifies grease into droplets small enough to travel through the pipe with the hot water. This works on soft, recent grease deposits. It does not work on hardened, built-up grease that’s been in the pipe for months.

For a complete grease blockage:
The plunger approach: place a standard cup plunger over the drain, create a seal, and pump 10–15 times with firm strokes. This can break up a grease plug near the drain opening. Follow immediately with hot water and dish soap flush.

If the drain doesn’t respond to plunging and hot water after two attempts, the clog is either further down the line or is an established wall buildup — stop adding water (you’ll overflow the sink) and call a plumber.

Why Does My Kitchen Sink Keep Getting Clogged With Grease?

A kitchen drain that recurrently clogs with grease has one underlying problem: grease is entering the drain regularly, and the pipe walls have a grease coating that catches new material.

The cycle:
1. Grease goes down the drain (from cooking, rinsing pans, food scraps with fat)
2. Grease cools as it travels through the pipe and deposits on the walls
3. The deposit narrows the effective pipe diameter
4. The narrowed pipe catches food particles and more grease
5. The drain slows, then blocks

Snaking the drain punches a hole through the clog, restoring flow — but leaves the grease coating on the walls. The coating catches the next round of grease within weeks. This is why recurring kitchen drain clogs respond to snaking temporarily but keep coming back: the root cause (wall coating) isn’t addressed by snaking.

The permanent fix is either hydro jetting (strips grease from the pipe walls) or stopping grease from entering the drain (using a grease trap or disposing of cooking grease in the trash). Ideally both.

Does Boiling Water Clear a Grease Clog?

Partially — and with an important caution.

What boiling water does: Melts grease that’s near the drain opening and has recently solidified. If you pour very hot water down the drain immediately after a grease-heavy cooking session, before the grease has hardened, it can keep the grease mobile and prevent a blockage.

What boiling water doesn’t do: Remove established grease deposits from the pipe walls further down the line. Grease that’s been building up for months is semi-hardened and adheres to the pipe walls — hot water from above reaches it briefly and may soften the surface but doesn’t strip the deposit.

The pipe safety caution:
– PVC drain pipe: Boiling water (212°F) can soften PVC and potentially deform connections at fittings. Use very hot tap water or water boiled and cooled to under 180°F.
– Cast iron, galvanized, or copper drain pipe: Tolerates boiling water safely.

If your pipes are plastic (which most homes built after 1970 have), use the hottest tap water rather than boiling water. It’s effective for recent grease and safe for all pipe materials.

How to Dissolve Grease Buildup in Drain Pipes

Hot water + dish soap (best DIY option):
As described above — works for recent deposits, not established wall coating.

Enzyme drain cleaners:
Products containing lipase enzymes (Bio-Clean, Green Gobbler Enzyme, Zep Enzyme) digest grease biologically. Pour them into the drain and let them sit overnight without running water. These work gradually and are better as a maintenance treatment — monthly use prevents buildup from accumulating to the point of blockage. Not effective for clearing a complete blockage.

Baking soda + vinegar:
Limited effectiveness on grease. Baking soda is mildly alkaline and can saponify (turn to soap) some grease on contact, but the reaction is brief and doesn’t reach grease deposits further in the pipe. Better for deodorizing and general drain maintenance than grease removal.

Chemical drain cleaners (Drano, Liquid-Plumr):
These are alkaline (lye-based) products that saponify grease, making it water-soluble. They’re more effective on grease than on hair. The limitations: they work on the top of the blockage but don’t penetrate to clear the full pipe wall; repeated use damages PVC pipe joints over time; and they create a caustic standing water situation if the drain doesn’t clear. Better to use once as an emergency measure than as a regular maintenance product.

Hydro jetting (professional):
The only method that actually removes grease coating from the pipe walls at meaningful depth. High-pressure water at 2,000–4,000 PSI strips the grease, restoring the pipe’s original internal diameter. A single hydro jetting session on a grease-coated kitchen drain typically provides 1–3 years of clear flow in a heavy-cooking household. This is the right long-term solution for a drain that’s been chronically clogged with grease.

Kitchen Sink Draining Slow After Cooking Grease

A kitchen sink that drains normally most of the time but becomes noticeably slow after a heavy cooking session — a large batch of meat, deep frying, or rendering fat — is showing the early sign of grease wall buildup.

What’s happening: the drain has narrowed from accumulated grease deposits. Under normal use, it drains adequately. Under heavy grease load, the narrowed pipe can’t handle the volume and backs up or slows dramatically.

Immediate response: Hot water and dish soap flush after every grease-heavy cooking session. This keeps the grease mobile before it hardens on the walls.

The longer-term read: A drain that slows under heavy use has established wall buildup. The flush treats the symptom. If the slowdowns are increasing in frequency or the drain no longer fully clears between cooking sessions, the buildup has accumulated to the point where hydro jetting is the appropriate treatment.

Does Baking Soda and Vinegar Work for Grease Clogs?

Partially — less than its reputation suggests for grease specifically.

What actually happens: Baking soda (sodium bicarbonate, alkaline) contacts the grease and slightly saponifies it — converts some of the fat to soap. The vinegar (acetic acid) then neutralizes the baking soda, producing carbon dioxide gas. The fizzing can dislodge loose material near the drain opening.

The limits: The reaction is brief (30–60 seconds of active fizzing) and doesn’t sustain long enough to penetrate established grease deposits. The grease further in the pipe is unaffected.

Better use: Baking soda and vinegar as a maintenance flush on a kitchen drain that’s still flowing — not as a fix for a blocked grease drain. Monthly use combined with hot water flushing helps slow the rate of buildup.

For an active grease blockage, the hot water + dish soap method is more effective.

Should I Use Drain Cleaner for a Grease Clog?

For a single acute grease clog: yes, a lye-based drain cleaner (Drano Max Gel, Liquid-Plumr) is more effective on grease than on hair and can clear a fresh grease blockage near the drain opening. Follow instructions exactly and flush thoroughly with water afterward.

Cautions:
– Never use in standing water — the product becomes highly caustic and working around it is dangerous
– Don’t use repeatedly — the alkaline chemicals degrade PVC drain pipe connections over time
– Don’t use before calling a plumber — if you need a plumber, tell them you’ve used chemical drain cleaner, as it creates a safety hazard

For recurring grease clogs: chemical drain cleaners are the wrong tool. They clear the immediate blockage but leave wall coating that causes the next one. Hydro jetting addresses the actual cause.

How to Prevent Grease From Clogging the Kitchen Drain

The most effective prevention is not putting grease down the drain:

• Cooking grease and fats: Pour into a jar, let solidify, dispose in the trash. Never pour liquid grease down the drain, even with hot water running.
• Greasy pans: Wipe with a paper towel before washing to remove the bulk of the grease before it reaches the drain
• Food scraps: Use a sink strainer to intercept food particles. Fewer food solids in the drain means less for grease to adhere to.
• Avoid “flushable” grease claims: Hot water and soap do not permanently neutralize cooking grease. They keep it liquid long enough to get further into the pipe, where it cools and deposits on the walls.

Monthly maintenance flush:
Run the hottest tap water for 2–3 minutes once a month. Add a few squirts of dish soap. This keeps recent grease deposits mobile and prevents the gradual narrowing that leads to recurring clogs.

Enzyme drain cleaner monthly:
An enzyme cleaner poured monthly and left overnight keeps biological grease deposits from accumulating. This works best in combination with not pouring grease down the drain — the enzyme digests the residual fat that makes it through despite best practices.

Grease Clog Deep in Pipe — How to Fix It

When a grease clog is further than 10 feet into the drain line — past the trap and into the branch drain or further — DIY methods don’t reach it effectively. Signs the clog is deep:

• Hot water and plunging don’t improve drainage at all
• The sink fills with water even with a trickle running
• Previous clearing (snaking) provided only temporary relief

Professional options:

Drain snake (auger): A motorized snake with 50–100 feet of cable can reach deep grease clogs and break them up. Effective for a discrete grease plug but doesn’t clean the pipe walls — the coating that caused the clog remains.

Hydro jetting: High-pressure water strips grease from the pipe walls along the entire length of the line. For a kitchen drain with years of grease buildup, hydro jetting is the comprehensive fix. The result: a pipe interior that’s close to its original diameter, which typically provides 1–3 years of trouble-free flow in a cooking-heavy household.

Camera inspection (add-on): For chronic kitchen drain problems, a camera inspection after hydro jetting confirms the pipe is clear and shows the pipe condition — identifying whether there’s any pipe damage contributing to the grease accumulation pattern.

How Much Does It Cost to Have a Plumber Clear a Grease Clogged Drain?

Seattle area (2026):

The cost comparison for a chronically clogged kitchen drain: if snaking at $150 needs to be done twice a year, that’s $300/year. Hydro jetting at $400 typically provides 1–3 years of clear flow — $130–$400/year depending on cooking habits. For heavy-cooking households, hydro jetting often costs less per year than repeated snaking.

Use the cost estimator for current rates in your city.

FAQ

Q: How do I unclog a kitchen drain full of grease?
A: For a fresh or mild grease clog: flush with the hottest tap water and 2–3 tablespoons of dish soap, wait 5 minutes, repeat. For an established blockage: plunge first, then hot water and soap. If neither clears it, the clog is deep or the pipe walls are coated — call a plumber for snaking or hydro jetting.

Q: Does boiling water clear grease clogs?
A: Boiling water can melt recent grease deposits near the drain opening. It doesn’t remove established wall coating further in the pipe. Use very hot tap water (not boiling) for PVC pipes to avoid softening the fittings.

Q: Why does my kitchen drain keep clogging with grease?
A: Repeated grease clogs mean the pipe walls are coated with grease from previous deposits. Snaking clears the current blockage but leaves the coating, which catches the next clog faster. Hydro jetting strips the walls clean and is the appropriate treatment for a chronically grease-clogged kitchen drain.

Q: Is it okay to pour grease down the sink with hot water?
A: No — hot water keeps grease liquid long enough to travel a few feet into the pipe, where it cools and deposits on the walls. Repeated over time, this builds a significant grease coating. Always dispose of cooking grease in the trash (pour into a jar, let solidify, discard).

Q: How much does it cost to clear a grease clogged kitchen drain?
A: Professional snaking for a kitchen grease clog runs $125–$250 in Seattle (2026). Hydro jetting, which cleans the pipe walls rather than just clearing the immediate blockage, runs $300–$500. For a chronic grease problem, hydro jetting is often more cost-effective over time.