3" PVC Sanitary Tee (DWV): Main Drain Connections
By Maintenance Depot Plumbing Team · Last reviewed
Quick answer
A 3" PVC DWV sanitary tee connects horizontal branch drains, often from toilets, to a vertical main stack. Install it on a vertical pipe with the curved inlet pointing down.
The 3" PVC sanitary tee (DWV) is one of the most important fittings in a home's drainage system. It connects horizontal branch drains, often from toilets, to the vertical main stack.
Specs at a glance
| Spec | Detail |
|---|---|
| Product | Sanitary tee |
| Size | 3" |
| Material | PVC |
| System | DWV (drain, waste, vent) |
| Typical use | Toilet and branch drains to the main stack |
What "DWV" means
Drain, Waste and Vent. DWV fittings are designed for gravity drainage, not pressurised water. They have smooth, curved internal paths that help waste flow.
Correct orientation
- Install on a vertical pipe.
- The curved branch inlet points down in the direction of flow.
- For horizontal-to-horizontal connections, use a wye or combination wye and 1/8 bend instead.
Typical uses
- Connecting a toilet drain to the main stack
- Tying in branch drains from bathrooms
- Vent connections
Installation steps
- Measure and cut the stack to fit the tee, allowing for socket depth.
- Dry-fit and mark alignment.
- Clean (and prime where required) all surfaces.
- Cement with DWV-rated PVC cement.
- Support the stack so the joints aren't under strain.
Slope horizontal drains
Branch drains should slope toward the stack at about 1/4" per foot for 3" pipe.
For bathroom sinks and smaller branches, see the 1-1/2" PVC sanitary tee.
Frequently asked questions
Can I use a sanitary tee for a horizontal connection?
No. Use a wye or combination wye and 1/8 bend for horizontal-to-horizontal connections.
What slope does a 3" drain need?
About 1/4" per foot is common; check local code.
Do I need special cement for DWV?
Use a PVC cement rated for DWV applications.