A leaking kitchen sink drain is one of the most common plumbing problems Sydney homeowners face. Whether you notice a puddle under the cabinet, a musty smell, or water stains on the cabinetry, acting quickly can save you from costly water damage. As a trusted plumber in Sydney, Hero Plumbing has helped thousands of homeowners diagnose and fix kitchen sink drain leaks, often on the same day.

Why Is My Kitchen Sink Drain Leaking?

Before you reach for the tools, it helps to understand what is causing the leak. Kitchen sink drain leaks almost always come from one of five places:

The drain basket seal: The putty or rubber gasket that seals the drain basket to the sink base degrades over time and allows water to seep through.
The P-trap connection: The curved pipe section beneath the sink can loosen or crack, particularly in older homes.
The drain pipe slip joints: Plastic slip joint washers wear out and no longer create a watertight seal.
The supply line fittings: Sometimes what looks like a drain leak is actually water dripping from a loose supply line that lands on drain pipes below.
A cracked drain pipe: Physical damage to the pipe itself, usually from impact or age-related deterioration.

What Tools Do You Need?

Adjustable pliers or a pipe wrench
Plumber’s putty or silicone sealant
Replacement P-trap or slip joint washers
A bucket and towels
A torch to see clearly inside the cabinet

Step-by-Step: How to Repair a Kitchen Sink Drain Leak

Step 1: Find the Source of the Leak

Place a dry towel under the sink, then run the tap and watch closely. Note exactly where the drip originates. Check the drain basket, the P-trap, each slip joint connection, and the waste pipe leading into the wall. Use your torch and take your time — misidentifying the source means you will fix the wrong thing.

Step 2: Turn Off the Water and Clear the Cabinet

Turn off the water supply valves under the sink before you start. Place a bucket under the P-trap to catch any residual water when you disconnect it. Remove everything from inside the cabinet so you have room to work comfortably.

Step 3: Fix a Leaking Drain Basket

If the leak is coming from around the drain basket where it meets the sink, the putty seal has failed. Unscrew the locknut from underneath the sink using pliers, lift the drain basket out from above, clean off all the old putty, and apply a fresh ring of plumber’s putty around the underside lip of the basket. Reseat it, tighten the locknut firmly from below, and remove any excess putty that squeezes out around the top.

Step 4: Replace Worn P-Trap Washers or the Whole P-Trap

If the leak is at a slip joint on the P-trap, hand-unscrew the slip joint nut, pull the joint apart and inspect the rubber washer inside. If it is flat, cracked or missing, replace it with a new washer of the same size. If the P-trap pipe itself is cracked or brittle, replace the whole P-trap assembly — they are inexpensive and straightforward to swap out.

Step 5: Reassemble and Test

Reassemble all connections hand-tight first, then give each slip joint nut a quarter turn with pliers. Do not overtighten plastic fittings or they will crack. Turn the water back on, run the tap for two full minutes, and check every joint with a dry paper towel. No moisture means the repair has held.

When Should You Call a Plumber?

Some kitchen sink drain leaks go beyond a simple DIY fix. Call a professional if the drain pipe inside the wall is leaking, you can see mould or water damage, you have already attempted a repair and the leak has returned, or the pipe is older cast iron or lead. A persistent leak may also point to a blocked drain in Sydney causing pressure to build up at weak joints. A licensed plumber can camera-inspect the drain and identify any blockage or damage further down the line.

How Much Does It Cost to Fix a Kitchen Sink Drain Leak in Sydney?

For a simple P-trap or washer replacement, most Sydney homeowners spend between $15 and $40 on parts if they do it themselves. If you call a plumber, expect a call-out fee plus labour — typically $150 to $300 for a straightforward repair. More complex repairs involving drain pipe replacement behind a wall will cost more and require a licensed tradesperson.

How to Prevent Kitchen Sink Drain Leaks

Avoid pouring grease or cooking oil down the sink — it solidifies in pipes and causes blockages
Run hot water for 30 seconds after washing dishes to flush food particles through
Check under the sink every few months for any signs of moisture or staining
Do not store heavy items in the cabinet that could knock or bend the drain pipes

Need a Hand? Hero Plumbing Is Ready Today

If your kitchen sink drain leak is beyond a quick DIY fix, Hero Plumbing is available seven days a week across Sydney. We offer same-day service, upfront pricing, and fully licensed plumbers. For urgent situations, our emergency plumber in Sydney is available around the clock. Call us today and we will have your kitchen back to normal in no time.