Can two toilets share the same vent?
Daniel Martin
Published Jan 11, 2026
Most houses have more than one toilet, and if they are on the same side of the house, their waste lines can usually tie into the same stack. If they are on opposite sides, however, each may need its own stack. Since the stacks must be vented, this would mean two vent openings on the roof.
Does each toilet need its own vent?
“Does a toilet need a vent?” And the answer is yes, your toilet has to have a vent. For more information on the great importance of plumbing vents, read our plumbing vent article here. And the size of this vent pipe depends on your local plumbing code.How many toilets can you have on one vent?
A horizontal wet vent could have as few as two fixtures or as many as ten fixtures but not more than two fixtures of any type can be connected to the system. Each wet vented fixture drain shall connect independently to the horizontal wet vent.Can a toilet share a vent?
Wet venting is most common in conjunction with toilets and sinks; the drain for the sink is also the vent for the toilet. It can also be used for a variety of other applications but due to the following rules this is the most convenient and common situation to run into.Can two bathrooms share a vent stack?
Venting two bathroom exhaust fans through one roof duct won't work, sorry to say. But you can install one fan in your attic for both bathrooms, and make your bathroom quieter, too.How Many Bathrooms With Toilets Can You Have In Your House - Plumbing Drain Pipe Size Matters
How do you vent two bathrooms?
How to Vent Multiple Bathroom Fans Through a Common Vent
- Install a Damper For Each Bathroom Fan.
- Choose Similar CFM Bathroom Fans.
- Common Vent Duct Must Be Over-sized.