I've installed a few but never used one. I've made them out of wood and out of concrete (I used to do a LOT of cast concrete). Commercially they're being embraced, choices are expanding. A little.

Some were artistic; a trough with a single faucet. Having a trough for the sake of having a trough.

Others were functional, essentially increasing the size of the sink bowl to get two usable spaces with two faucets out of a spot where two individual sinks would look cramped.

I did a cast concrete trough sink with three faucets for a couple that had triplets.

Never heard anything negative back from anyone.

Thanks you two. We would have 2 faucets. And we don't usually cross paths when getting ready in the morning, so it's not so much a tightness of space when together issue. It just seems that his shaving soap always makes the drain run slow. For some reason that really bugs me!

Mongo, when you did the troughs with multiple faucets, did they have just 1 drain? If so, I might be back to the issue that makes me dislike 1 sink.

It seems like it could lend a contemporary style to the bath. I'll see if I can scan and post the floor plans, to give a better idea of the limited nature of the bath.

"Mongo, when you did the troughs with multiple faucets, did they have just 1 drain? If so, I might be back to the issue that makes me dislike 1 sink. "

Excellent question.

I've done both.

If you want one drain per faucet, then you can use standard drain setups. They might be either 1-1/4" or 1-1/2". Just make sure that underneath the sink, when the multiple flows joint together, that the drain pipe is at least 1-1/2" or even a 2". that goes for the trap and the horizontal branch drain that runs out of the trap and into the wall.

If you want a single drain for two or three faucets, or two drains for three faucets, then do not use a 1-1/4" drain. Use a 1-1/2" drain in the sink itself. Then continue with 1-1/2" under the sink, or again, if you want to up it, you can go to 2".

Typically, a bathroom faucet will supply 1DFU of water. A 1-1/2" system can handle 3DFU of water, 2" 6DFU.

Some local codes can be different. So the safe thing would be to run the trough installation past your local inspector.

I agree in a general sort of way. Feel free to think that a 1.25" diameter pipe will work fine as well.

A lot depends on local norms.

Since the fixtures are never used all at the same time, UPC and IPC codes have a concept of "Bathroom Group" which compensates for the intermittent use of the fixtures. Straight adding the DFU numbers for all fixtures produces a higher number than ever, when you have more faucets. The notion of a Bathroom Group lowers this total.

Take no action based on having learned this from me here. Find out more elsewhere. Post if you wish to share.

David, good point to bring up.

My local interpretation of the code is that that the grouping value would be for the branch line that drains the group itself; the tub/shower, the toilet, the sink. It allows you to downsize the branch pipe that drains that group as a whole.

However, if the group has something else added to it, say a second sink, then you lose the group efficiency and you have to go back to adding up the individual DFUs for each individual item in the bath. You can't just add another 1DFU for the extra sink to the previous group value.

Example, if we have a standard bathroom with tub (2DFU), lav (1) and toilet (3), we add up the individual DFUs and get 6. However, just as David mentioned, it's unlikely that the three fixtures will be in use at the same time. So we can group the bathroom and the group as a whole only needs a drain capable of carrying 5DFUs. However, if we add a second lav to that setup, we lose the grouping and have to add things up individually. Now the drain would have to be sized for 7DFUs.

Going onward, there are also group values for multiple bathrooms in a house. If a house has 2-1/2 standard bathrooms, with no grouping values at all the line that all three baths drain in to would have to be 6+6+4=16DFUs.

Taking into account the single bathroom grouping efficiency, which drops a bathroom from 6 to 5DFUs, we'd need a line capable of draining 5+5+4=14DFUs.

However, there is a 2-1/2 bathroom grouping as well that's calculated at 9DFUs. That takes into consideration that idea that it's not very likely that all three toilets, all three sinks, and the two tubs/showers will be in use at the same time.

More info than requested, but hey...what the hey-hey. But again, as David mentioned, local code and interpretations can vary.

David and Mongo, excellent reminders that it's rarely just a design question!

Just passing through

Click on the link below for images of trough sinks

Here is a link that might be useful: trough sinks