Only when the sink runs
Waste side: trap, waste outlet, washer or plastic pipe.
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Leak Under the Sink: Trap, Hoses and Tap Repaired
The bottom of the cupboard is wet, a drip falls from the trap or a puddle appears every time you empty the sink? A plumber finds the leak and repairs it, 7 days a week, before the cabinet and floor are damaged. The price is given before the work.
5,0on Google· 22 years of experience
Leak foundTrap, hose, tap
7 days a weekEvenings and weekends
Price given firstBefore the repair
One officePlumbing and drains
Trap, waste and drain pipe
A leak under a sink most often comes from the waste side: a loose trap nut, a hardened washer, a waste outlet that no longer seals or a cracked plastic pipe. It only shows when water runs, which is why it is easily confused with a supply leak.
To tell: empty the cupboard, dry everything and run the sink for a few minutes while watching with a torch. If water beads under the trap or along the pipe, it is the waste. Hand-tightening is sometimes enough; if the washer is squashed or the trap cracked, it needs replacing.
The plumber removes the trap, clears grease deposits, replaces washers or the damaged part and checks the pipe fall to the wall. If a trap leaks because the sink drains slowly, there is often a blockage further along: he deals with it at the same time.
When the leak comes from a blocked sink
A sink that drains poorly puts the waste pipe under pressure: water rises, overflows at the plug hole or pushes on the trap joints, which end up leaking. Fixing the washer without clearing the drain means the same leak a few weeks later.
In a kitchen, the blockage is almost always grease and food waste set in the pipe, sometimes several metres away. Shop-bought drain cleaners attack seals and do not dissolve this kind of blockage.
The technician runs an electric drain snake down to the blockage, breaks it up and flushes the pipe. He then refits the trap with new washers and checks everything stays watertight with the sink draining at full flow.
Leak under the washbasin and damaged unit
In the bathroom, leaks under the basin follow the same rules: trap, waste, mixer hoses. But bathroom units, often made of chipboard, swell very quickly when they get wet.
When the bottom of the unit is warped or the doors no longer close, the plumber can fix the leak and replace the vanity unit straight away: remove the old one, fit and fix the new one, connect the mixer and waste, finish with silicone.
He also checks the isolation valves under the basin. They are rarely used, seize with limescale and sometimes leak through the spindle: replacing them means you can easily turn off the water in future.
Where is the leak coming from?
Look at where and when the water appears: it usually tells you which part is at fault.
All the time, even with the sink empty
Supply side: tap hose, fitting or isolation valve. Turn it off quickly.
When the dishwasher runs
Its drain hose loose on the trap, or its supply connection.
At the base of the tap
The seal under the mixer or the tap itself: water runs down the hoses.
Swollen or rusty hose
A damaged braided hose can burst: replace it without waiting.
How the repair works
Describe the leak
When it appears and, if possible, a photo under the sink. We book the first available visit.
Diagnosis and price
The plumber finds the faulty part and gives you the price before repairing.
Tested repair
He replaces the part, tests at full flow and hands you the job sheet.
What our customers say
Where do we work?
Our plumbers work throughout Belgium: Brussels, Flanders and Wallonia. For a leak, call us and we will tell you when a plumber can come.
BrusselsWalloon BrabantFlemish BrabantHainautNamur provinceLiège provinceLuxembourg provinceAntwerpEast FlandersWest FlandersLimburg
The brands we work with
Our technicians work on all brands: they install, service and repair appliances from the major manufacturers. For a new installation, we recommend the model that suits your home and budget.
We buy our equipment from all the major Belgian wholesalers and suppliers, including Facq, Van Marcke, Desco and STG: genuine parts, quickly available.
Frequently asked questions
What should I do straight away?
Close the isolation valves under the sink, or the main stopcock if the leak is on the supply, empty the cupboard, put a bowl down and dry it out. Then call us on 0477 03 88 98.
Can I tighten the trap myself?
Yes, by hand without tools so as not to crack the plastic. If it still leaks, the washer is probably damaged.
Can a tap hose burst?
Yes, especially if it is rusty, swollen or old. A burst hose floods a kitchen fast: replace it if in doubt.
My sink leaks and drains slowly. Are they linked?
Often. A blockage pressurises the waste and makes joints leak. The technician clears and repairs in one visit.
How much does the repair cost?
A washer or trap is quick; a tap or a unit takes more. The plumber gives you the price before starting.
Do you come at weekends?
Yes, 7 days a week. Any extra charge is quoted on the phone.
Will my insurance cover the damage?
Water damage is often covered. Take photos; our job sheet describes the cause of the leak.
A leak under your sink?
Call us for a repair, book a slot online or request a quote.