Gushing Leak Under Sink? Stop the Water Fast!

By The FixDelivered Team · Updated 2026-08-03 · 6 min read

Discovering a gushing leak under your sink is a homeowner's nightmare. Whether it's a burst pipe under sink or a simple connection failure, the sight of water rapidly filling your cupboard can send anyone into a panic. The good news is that by acting fast, you can minimise damage and get the situation under control. This guide will walk you through the immediate steps to take, potential temporary fixes, and when it's crucial to call a professional.

Immediate Action: Stop the Water Flow

Your absolute priority when facing a water gushing under sink scenario is to stop the flow. Every second counts to prevent extensive water damage to your kitchen units, flooring, and potentially ceilings below.

1. Turn Off the Isolation Valve

Most sinks have individual isolation valves (sometimes called service valves) located on the hot and cold water supply pipes directly underneath the sink. These are usually small, quarter-turn valves or screw-down valves. Turn them clockwise until they are fully closed. This will only cut off the water supply to that specific tap.

2. Locate and Turn Off Your Main Stopcock

If you can't find or operate the isolation valves, or if the leak isn't from the tap's supply lines (e.g., a waste pipe or a major burst), you'll need to turn off the main water supply to your entire home. Your main stopcock is typically found:

Under the kitchen sink.
In a downstairs toilet or utility room.
In the garage.
Near the front door, often under the stairs.

Turn the stopcock clockwise until it's fully closed. If it's stiff, use caution and don't force it excessively. Once the water is off, open a cold tap at the lowest point in your house (e.g., a garden tap) to drain the remaining water from the pipes.

3. Unplug Electrical Appliances

If water is spreading and there are electrical sockets or appliances nearby, switch off the power at your consumer unit (fuse box) to prevent electrical hazards.

4. Contain the Water

Grab buckets, bowls, and plenty of towels to collect the water and soak up any spillage. This will help prevent further damage while you assess the situation.

Identify the Source of the Leak

Once the water is off, you can safely investigate the cause of the leak under sink. There are two main types of leaks:

Clean Water Leaks: These come from the hot or cold water supply pipes leading to your tap. The water will be clear.
Foul Water Leaks: These come from the waste pipe or trap connected to the sink, carrying used water away. The water may contain food particles or soap residue.

Common culprits for a gushing leak under sink include:

Loose Compression Fittings: Where pipes join using nuts and olives.
Perished Washers or Seals: Inside pipe connections or tap components.
Corroded or Burst Pipes: Especially older copper or plastic pipes.
Damaged Waste Trap (S-trap or P-trap): Often due to impact or age.
Cracked Sink Basin: Less common, but possible.

DIY Temporary Fixes for Under-Sink Leaks

For minor leaks, a temporary fix might buy you time until a professional can arrive. However, if it's a significant burst or you're unsure, always call a plumber.

Tools You'll Need

Bucket and towels
Adjustable wrench or spanner
Screwdriver set
Pipe repair clamp (for supply pipes)
Self-amalgamating tape (for supply pipes)
PTFE tape (for threaded connections)
Rubber gloves

Safety First!

Always ensure the water supply is off before attempting any repairs.
Be aware of hot water if the leak is from the hot supply.
If any electrical components are wet, ensure the power is off at the consumer unit.

Step-by-Step Temporary Fixes (Proceed with Caution!)

Tighten Connections: For leaks around nuts on supply pipes or the waste trap, gently try tightening them with an adjustable wrench. Do not overtighten, as this can strip threads or crack plastic components.
Apply a Pipe Repair Clamp: For a small hole or crack in a metal supply pipe, a pipe repair clamp can provide a good temporary seal. Position the rubber gasket over the leak and tighten the clamp securely around the pipe.
Use Self-Amalgamating Tape: For small splits in supply pipes, this tape can be a lifesaver. Stretch the tape as you wrap it tightly around the pipe, overlapping each layer. It fuses to itself to create a waterproof seal. Do not use standard electrical tape.
Check the Waste Trap: If the leak is from the U-bend (trap), check if the large nuts on either side are tight. If the trap itself is cracked, you may be able to temporarily wrap it with strong waterproof tape (like duct tape) and place a bucket underneath.
Apply PTFE Tape: If a threaded connection is leaking, you might be able to undo it (with water off!), clean the threads, wrap several layers of PTFE tape clockwise around the male thread, and then re-tighten.

When to Call a Professional Plumber

While temporary fixes can help in a pinch, a gushing leak under sink often requires professional attention to ensure a lasting and safe repair. You should call an emergency plumber if:

You cannot locate or turn off the water supply.
The leak persists after your attempts at a temporary fix.
The leak is from a hot water pipe and you are uncomfortable working with it.
It's a significant burst pipe under sink that you can't contain.
You're unsure about the source or the nature of the leak.
The leak has caused significant flooding or damage.

A professional plumber has the right tools, experience, and parts to diagnose and fix the issue correctly, preventing future problems. Typically, an emergency plumber's call-out fee in the UK (2026) might range from £80 to £150, with hourly rates on top, depending on the time of day and the complexity of the job. For reliable, qualified help, you can find emergency plumbers near you quickly through FixDelivered.

Preventative Measures

Regular checks can help prevent a future leak under sink:

Periodically inspect pipes and connections under your sink for any signs of dampness, corrosion, or drips.
Avoid using harsh chemical drain cleaners, as they can corrode pipes over time.
Don't overload your sink with heavy items that could stress the waste connections.
Ensure that anything stored under the sink isn't pressing against pipes or connections.

How FixDelivered Can Help

When you have a water gushing under sink emergency, you need fast, reliable help. FixDelivered connects you with qualified local plumbers who can attend to your emergency quickly. Our booking fee is refundable if no plumber is found, and the plumber's callout fee is agreed upfront. Don't let a burst pipe under sink turn into a disaster – tell us your emergency and get a professional plumber on their way.

Frequently asked questions

What causes a leak under the sink?

Common causes include loose compression fittings, perished washers or seals, corroded or burst pipes, or a damaged waste trap (U-bend). Wear and tear, impact, or improper installation can all contribute.

Can I fix a gushing leak myself?

You can take immediate steps to stop the water flow and apply temporary fixes like pipe repair clamps or self-amalgamating tape for small leaks. However, for a gushing leak or significant damage, it's always best to call a professional plumber to ensure a permanent and safe repair.

How much does it cost to fix a leak under the sink?

The cost varies depending on the severity of the leak, parts needed, and your location. In the UK (2026), an emergency plumber's call-out fee might be £80-£150, plus labour costs (e.g., £60-£100 per hour) and materials. Minor fixes could be cheaper, while burst pipes requiring significant pipe replacement will be more.

What should I do if the leak is from a hot water pipe?

Immediately turn off the hot water isolation valve under the sink, or the main stopcock for your home. Be extremely careful as hot water can cause burns. Once the water is off, you can attempt a temporary fix, but it's highly recommended to call a professional plumber due to the higher risk associated with hot water systems.

Need a plumber now? Tell us your emergency and FixDelivered will find and confirm an available local plumber near you, usually within the hour.

Written by the FixDelivered Team. Reviewed by Rupert Lowe, Editor. Last updated 2026-08-03.