A kitchen sink that smells

Introduction

The sink smells from the bowl or the cupboard even while the water still runs away. Grease sits in the bottle trap. It is not the trap of a bathroom left shut. If the water also sits, clean the cup and then look at a slow drain.

How to tell it apart

A smell in the cupboard, a greasy cup, a film on the grille: the grease is in the trap.

A smell from the hole under the rim, with a clean bowl: that is the overflow, not the tap.

A smell when the dishwasher drains, or the machine’s hose joined to the sink: that connection. It should meet the fitting, not hang in the cupboard.

Several fittings, or the ground floor with other wastes rising: the stack. A guest bathroom on its own is a bathroom waste that smells. Slow water without this smell is a slow drain.

Likely causes

• Grease and scraps in the bottle trap.
• A dirty overflow that smells even when the cup is clean.
• A dishwasher hose that is loose, or a trap that empties when the machine drains.
• A union washer that does not hold: air leaks into the cupboard.
• The stack, when several fittings smell together.

What to do now (€0)

1. Lift the grille and pick out what you can see. Do not pour a product.
2. To rinse, use water that is very hot but not boiling. Boiling water does nothing useful to plastic pipe: if it throws up a thick steam, it is already too hot. There is no figure to guess.
3. Pour a little water into the overflow and see if the smell comes from there.
4. Look at the dishwasher hose. Do not pull it off if you cannot put it back on the fitting.
5. If the smell stays, put a bowl under the trap. Do not pour a chemical before you have emptied it.

A small DIY step

1. Undo the cup’s unions by hand, empty the grease into the bowl, rinse, and refit the washers as they were. No pliers on the plastic.
2. A cracked trap: measure the outlet, Ø32 or Ø40, and replace the part. Do not wrap it.
3. An air gun only with an intact trap, one waste, and no thin glass. If the water is slow, the plunger with the overflow plugged is on the slow-drain page.
4. No caustic soda as a first move. The quiz cards, when they show, are category examples.

Mistakes to avoid

• Pouring cooking oil and grease down the sink.
• Two different drain chemicals, together or one after the other.
• Caustic soda to “dissolve” a stack.
• Forcing plastic unions.
• Boiling water in the sink.

When to call a professional

A plumber if the trap is built in, the unions will not turn, or the smell returns as soon as you refit it.

A plumber, and the building manager if you are in a block, when several fittings smell or other wastes rise on the ground floor.

Safety

A smell of gas in the kitchen is not the trap. Do not light the hob and do not flip a switch. Open the windows, close the meter tap if you can reach it, leave, and call the distributor’s emergency number on the bill, or 112 if there is danger. Gas and the boiler: a qualified technician.

Do not mix bleach with ammonia or with acids and descalers. Gloves, air, read the label, stop if you smell fumes. Acids and vinegar do not go on a marble or natural-stone sink.

Questions people ask