Under sink manifold

I've come across this before where there was a common trap for the two sinks. The only way is to completely dismantle the plumbing and give it a good clean. Last time I found a number of hard items that were clogged with fat and junk to form a blockage. You could fill one sink and the other filled in sympathy.

I wouldn't expect a different configuration to perform much better. Just make sure there is a fall in each pipe. Perhaps an individual trap for each sink if not already.

I had the same problem so used two traps and joined the outlets from the traps - problem solved. I suspect the problem's caused by slow flow along the horizontal bit, so joining with a vertical Y removes the cause.

They're ok for liquids, but tend to block easily if any solid matter goes down - such as the output from a waste disposal device. If possible, try to arrange for there to be only one solid material inlet, and for it to be directly in line with the outlet - so that solids don't need to move horizontally. I had the same problem, which was fix when I re-jigged the inlet connections.

Thanks to all for the suggestions. I think I?ll break a new hole in the wall and pipe the waste disposal and dishwasher out through it.Part of the problem is the convoluted pipe work to get to the outside drain.I?ll need an elbow where the new outlet turns down to the drain, I?ll put a rodding eye there

One that can be taken apart to clean it. Actually I never liked waste disposal devices myself, more trouble than they are worth. At least a blocked sink is simple easy to understand plumbing, even if you find the very bit you need to undo isstuck and it all breaks when you use some large wrench on it. grin. Brian