How to Fix a Blocked Sink – Complete Guide

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8 min read|Updated: Jun 27, 2026|By Home Repair Expert

Quick Answer

A blocked sink is cleared in three escalating steps: first, baking soda and vinegar followed by very hot water (light clogs). Second, remove and clean the P-trap under the sink with a bucket below (medium clogs). Third, run a small drain snake or auger through the pipe past the P-trap (deep clogs). Avoid chemical drain cleaners, which damage pipes and rarely clear stubborn blockages.

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A blocked sink, with water sitting stubbornly in the basin or draining painfully slowly, is one of the most common household plumbing problems. Whether it is a kitchen sink clogged with grease or a bathroom basin blocked with hair and soap, you can almost always clear it yourself with simple methods, no harsh chemicals or plumber required.

This guide takes you through clearing a blocked sink step by step, starting with the easiest methods and working up to clearing the trap, plus how to keep it draining freely afterward.

What Causes a Blocked Sink

Sinks block from the everyday material that washes down them. The usual causes are:

• Grease and fat: In kitchen sinks, cooking fats congeal in the pipe and trap other debris, the leading cause of kitchen blockages.
• Hair and soap: In bathroom basins, hair binds with soap scum to form a stubborn plug.
• Food scraps: Bits of food washed down a kitchen sink build up and clog the trap.
• A blocked trap or pipe: Debris settles in the U-bend (trap) under the sink, the most common place for a blockage to form.

Tools and Materials You Will Need

• Plunger (cup plunger)
• Bucket and shallow tray
• Baking soda and white vinegar
• Boiling or very hot water
• Adjustable wrench or pliers
• A wire or drain snake
• Rubber gloves
• Old toothbrush

Step-by-Step: How to Clear a Blocked Sink

Step 1: Try Hot Water and Baking Soda

For a partial block, pour boiling water down the drain (use hot tap water for PVC pipes). If that is not enough, add half a cup of baking soda followed by a cup of white vinegar, leave it to fizz for 15 minutes, then flush with hot water.

Step 2: Plunge the Sink

Block any overflow opening with a damp cloth, fill the basin with enough water to cover the plunger cup, and plunge firmly and repeatedly. The suction and pressure shift most blockages in the pipe.

Step 3: Clean Out the Trap

If plunging fails, place a bucket under the U-bend trap, unscrew it, and clear out the gunk and debris inside. The trap is the most common spot for a blockage, and clearing it solves most stubborn cases.

Step 4: Snake the Pipe

For a blockage further along, feed a drain snake or stiff wire into the pipe, twist to hook the clog, and pull it out. Then reassemble the trap.

Step 5: Flush and Test

Run hot water for a minute to confirm the sink drains quickly and freely, washing away any loosened debris.

Pro Tips to Prevent This Problem

• Use a sink strainer to catch food and hair before they enter the pipe.
• Never pour grease or fat down a kitchen sink, let it cool, solidify, and bin it.
• Flush drains with hot water regularly to stop buildup forming a blockage.

When to Call a Professional

Call a plumber if the blockage will not clear, if several sinks or drains are blocked at once, or if water backs up from multiple fixtures. These can indicate a blockage deep in the main drain line that needs professional drain-clearing equipment.

Frequently Asked Questions

What is the fastest way to unblock a sink?

A cup plunger is usually the quickest method, block the overflow, cover the plunger with water, and plunge firmly. For grease or partial blocks, hot water with baking soda and vinegar works well first.

Should I use chemical drain cleaners on a blocked sink?

They can damage pipes and often fail on grease and hair. Plunging, the baking soda and vinegar method, and clearing the trap are safer and usually more effective.

Why does my sink keep blocking?

Recurring blocks usually mean grease, hair, or food is still entering the drain. Fit a strainer, keep fats out of the sink, and flush with hot water regularly to prevent buildup.

Final Thoughts

A blocked sink is rarely a job for a plumber. Start with hot water and baking soda, move on to plunging, and clear the trap if the clog persists, snaking the pipe for anything deeper. Fit a strainer and keep grease and hair out of the drain, and you will keep your sink running freely, calling a plumber only if multiple drains block at once.