Engineering ToolBox - Resources, Tools and Basic Information for Engineering and Design of Technical Applications!

Drainage Fixture Unit Values - DFU

DFU are used to determine the drainage from fixtures and required capacity of sewer service systems

Sponsored Links

DFU (Drainage Fixture Unit Values) is defined by the the Uniform Plumbing Code (UPC) and can be used to determine required drainage capacities from fixtures and their service systems.

Individual Appliance, Appurtenance or FixtureMinimum SizeDrainage Fixture Unit Values
(inch)Private InstallationsPublic Installations
Bar sink 1 1/2 1 1
Bathroom (water closet, lavatory, bidet and tub or shower) 3 6 -
Bathtub 1 1/2 2 2
Bidet 1 1/4 1  
Bidet 1 1/2 2  
Clothes Washer 2 3 3
Dishwasher, domestic 1 1/2 2 2
Drinking fountain 1 1/4 0.5 0.5
Floor drain 2 2 2
Shower 2 2 2
Laundry tub 1 1/2 2 2
Lavatory 1 1/4 1 1
Bar sink 1 1/2 1  
Kitchen sink, domestic 1 1/2 2 2
Laundry sink 1 1/2 2 2
Service or mop basin 2   3
Urinal 2 2 2
Water closet with gravity tank 3 3 4
Water closet with flushometer tank 3 3 4
  • 1 WFSU = 1 GPM = 3.79 liter/min

Note that this conversion is only true for one or a few fixtures. Since the fixtures in a system are never used all at the same time, the total units (capacity) achieved by adding the numbers for all fixtures must be compensated for intermittent use if we want a realistic estimate of the total drainage load.

Sponsored Links

Related Topics

Related Documents

Tag Search

  • en: drainage sewage fixture capacity unit values dfu
Sponsored Links

Search the Engineering ToolBox

Engineering ToolBox - SketchUp Extension - Online 3D modeling!

3D Engineering ToolBox Extension to SketchUp - add parametric components to your SketchUp model

Add standard and customized parametric components - like flange beams, lumbers, piping, stairs and more - to your Sketchup model with the Engineering ToolBox - SketchUp Extension - enabled for use with the amazing, fun and free SketchUp Make and SketchUp Pro .Add the Engineering ToolBox extension to your SketchUp from the SketchUp Pro Sketchup Extension Warehouse!

Translate this page to
About the Engineering ToolBox!


We don't collect information from our users. Only emails and answers are saved in our archive. Cookies are only used in the browser to improve user experience.

Some of our calculators and applications let you save application data to your local computer. These applications will - due to browser restrictions - send data between your browser and our server. We don't save this data.

Google use cookies for serving our ads and handling visitor statistics. Please read Google Privacy & Terms for more information about how you can control adserving and the information collected.

AddThis use cookies for handling links to social media. Please read AddThis Privacy for more information.


This page can be cited as

  • Engineering ToolBox, (2009). Drainage Fixture Unit Values - DFU. [online] Available at: [Accessed Day Mo. Year].

Modify access date.

. .


3D Engineering ToolBox - draw and model technical applications! 2D Engineering ToolBox - create and share online diagram drawing templates! Engineering ToolBox Apps - mobile online and offline engineering applications!

Scientific Online Calculator

Scientific Calculator

3 15

Sponsored Links