Trap versus "S" Bend

[Frank]

Can a bathroom sink have an S Bend as apposed to a waste trap?

Apart from preventing smells coming up the pipe, is the traps main function to collect anything that gets dropped down the sink and if so then why does a bath not have this?

Cheers

Frank.

[Set Square]

They both do the same job - provide a plug of water which prevents nasty smells coming up to the sink/bath/basin/whatever from the sewer. A trap is more compact, and takes up less horizontal space, in particular. Otherwise it doesn't matter which you use. A lot of baths *do* have traps.

Modern plastic S-bends are often not very deep (their lead pre-decessors had used to be a lot deeper). P-traps come in various depths. You sometimes need a deep one if the waste pipe isn't adequately ventillated such that the pressure can drop and suck the water out of the trap. Deeper traps offer more resistance to this.

[Frank]

Thanks Set Square.

[Chris Bacon]

Of course not. There is no such thing as a bathroom sink.

It does.

[Peter Taylor]

I think what Frank means by "trap" is a Bottle Trap. An S bend is a trap as well, Frank. So is a P trap. You can get S traps, P traps and bottle traps in all diameters, 32mm for washbasins and bidets, 40mm for sinks, baths and showers and 50mm, usually for Urinal bowls and large sinks. You can also get shallow 40mm dia P traps for tight spaces under baths and showers. If you want an S trap for a basin, you need one of these, in 32mm or 1¼" diameter:

trap's function is to provide a water seal to prevent bad smells from the sewers. Luckily, they all catch dropped jewellery too. This type can be disassembled very easily to do that.

Peter

[PeTe33]

I recently found on both kitchen sink & wash basin, an S trap/bend makes for very simplified connection to an off centre outlet/rising pipe. Both for depth and left/right adjustments.