Hello, have a 4m run of 50mm pipe for the shower. The layout of joists, closeness of corner walls etc mean that it would be very helpful to be able to add the basin waste to a swept tee in the shower waste and this could be between 300-800mm from the soil stack . I've read elsewhere very mixed responses to teeing in wastes, some saying it's OK and some saying it'll syphon the water out of one or both traps. I'd value the opinions from this forum. Many thanks.