One slow sink usually means a blockage in that fitting's waste pipe, close to the trap. It is cleared at the sink, and the drain outside is left alone.
When several fittings back up together, the underground drain is blocked and is cleared from the manhole. Rods or a water jet break up the blockage, and the flow is checked before the covers go back.
What the work covers
Indoor fittings cleared with plungers and augers, with traps taken apart where needed.
Leaves, silt and fat lifted out of yard gullies and the pipe beyond them.
Chambers emptied and the blocked run rodded or jetted through to the next chamber.
Grease-blocked waste pipes from sinks and dishwashers cleared in cafés, pubs, shops and canteens.
Questions people ask
How much does it cost to unblock a drain?
The price depends on where the blockage is, how easy the manholes are to reach, whether rods clear it or jetting is needed, and what is causing it. Saying which fittings are affected helps price it.
Will Welsh Water clear a blocked drain for free?
If the blockage is in a shared sewer or a lateral drain they are responsible for, yes. A drain that serves only your property and is within your boundary is yours to clear.
Are chemical drain cleaners worth trying first?
They can shift a light build-up in a sink trap. They rarely clear a solid blockage in a main drain, and they make the pipe hazardous to work on afterwards, so tell us if you have used one.
Why does my toilet gurgle when the bath empties?
Both fittings share the same drain. Gurgling usually means air is being pulled through a water seal because the pipe below is partly blocked or poorly vented.