Service
Under Sink Leak Repair
Fixing leaks in the cabinet under a sink, where supply valves, flexible connectors, trap joints and the sink seal all fail in different ways.
- Licensed and insured
- Price agreed before work
- A plumber who works your area
Two tests, four sources
A dark cabinet with water in the bottom hides which of four things failed. Ten minutes separates them.
Dry everything completely first, because standing water tells you nothing.
Run the tap with the plug out. This pressurises the supply and sends a steady flow through the trap. A leak now is either supply or waste, so watch where it starts.
Fill the bowl and pull the plug. A large volume goes through the waste at once, which finds joints that a trickle passes.
Look at the outside of the drainpipe. If water is running down it from above rather than escaping from a joint, the sink flange seal has failed and the pipework is innocent.
Look at the valve stems. A weep from the shutoff itself often only appears once the valve is turned.
The connector that floods houses
One part under a sink deserves more attention than the rest.
Braided flexible supply hoses have a finite life, and when they fail they do not drip. The braid corrodes, the inner tube lets go, and an open supply line runs into a cabinet at full pressure, typically while nobody is home.
They cost very little and take minutes to change. Any that are visibly corroded, bulging, or simply old are worth replacing while someone is already under there, and it is the cheapest insurance in the house.
Does this sound familiar?
Problems this service solves
- Water pooling in the base of a sink cabinet
- A shutoff valve weeping at the stem
- A flexible supply connector that has begun to seep
- A trap joint dripping after every use
- A swollen cabinet base with no obvious source
Signs you need under sink leak repair
If more than one of these is true, the problem is usually past the point a plunger or a store-bought cleaner will fix.
- The cabinet floor is damp or discoloured
- There is a musty smell under the sink
- Water appears only after the sink is used
- White or green crust on a valve or fitting
What to expect
How the visit works
Dry it and watch
A dry cabinet makes the source obvious. Running the tap, then filling and draining the bowl, separates supply leaks from waste leaks in a couple of minutes.
Check the connectors
Flexible supply hoses age and fail, sometimes catastrophically. Any that are old, corroded or weeping get replaced rather than tightened.
Reseal or replace trap joints
Slip joints, washers and the tailpiece connection are remade properly. Over-tightening a cracked plastic nut is a very short-lived repair.
Check the sink seal and disposal
Water running down the outside of the waste comes from the sink flange seal or a disposal gasket, not from the pipework at all.
What's included
What you get on every job, whoever we send.
- The four common sources separated before parts are bought
- Ageing supply hoses replaced, not retightened
- Trap joints remade rather than forced tighter
- Cabinet damage checked, since it hides the source
Questions
Under Sink Leak Repair questions
How do I tell a supply leak from a drain leak?
Dry everything thoroughly, then test in two stages. Run the tap for a minute with the plug out and watch: that pressurises the supply and moves water through the trap. Then fill the bowl and pull the plug, which sends a large volume through the waste all at once. A leak that shows up under pressure with the tap off is supply. One that only appears on a full drain is the waste side. Five minutes with a torch saves guessing.
Should I replace flexible supply hoses even if they are not leaking?
If they are old, yes. Braided flexible connectors have a service life, and their failure mode is unusually bad: the braid corrodes, the inner tube gives way, and instead of a drip you get a full-bore supply pipe running into a cabinet. It happens while people are out. They are inexpensive parts, they are quick to change, and replacing ones that show any corrosion or bulging is one of the better small decisions in a house.
Water is running down the outside of the drainpipe. What is that?
That is not the pipework leaking. Water is getting past the seal where the waste fitting meets the sink itself, then running down the outside of the pipe and dripping from the lowest point, which makes it look like a pipe joint. On a sink with a disposal, the unit's mounting gasket does the same thing. The fix is resealing the flange, and no amount of tightening the pipe joints below will change it.
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Get it fixed
Under Sink Leak Repair, handled locally
Call with your ZIP code and what you are seeing. We route you to a licensed plumber in your area who does under sink leak repair every week.
- Licensed and insured
- Answered 24/7
- Price before work