How to Combine Toilet & Sink Drains
How to Combine Toilet & Sink Drains B athrooms usually have more than one plumbing fixture, and it’s inconvenient and expensive to run individual drain lines from each fixture to the house’s main sewer line. Instead, plumbers connect drain lines in the floor beneath the bathroom and install a common vent that allows water and waste to drain without forming an airlock. The toilet has the largest drainpipe, so the sink drain, which is smaller in diameter, will empty into the toilet drain line. The Toilet Drain 1-Connect a 3-inch PVC closet bend to the bottom of the toilet flange located in the floor where the toilet will sit. A closet bend is sweeping 90-degree elbow that connects the flange to a 3-inch drainpipe that runs between the floor joists. There is no need to install a trap beneath the toilet because toilets have built-in traps. 2-Attach the open end of the closet bend to a horizontal 3-inch drainpipe. The drainpipe runs horizontally only until it can des...