Water Supply

NSPC Fixture Unit Table

NSPC-specific WSFU values for common plumbing fixtures, differing from both IPC and UPC.

Introduction

The National Standard Plumbing Code (NSPC) defines its own Water Supply Fixture Unit values. These differ from both IPC and UPC values. Plumbing Booster includes NSPC fixture tables for NSPC-compliant designs.

NSPC Selected WSFU Values

Fixture	Occupancy	Supply Control	Cold WSFU	Hot WSFU
Water closet	Private	Flush tank	4	0
Water closet	Public	Flush tank	4	0
Water closet	Public	Flushometer valve	5	0
Urinal	Public	Flushometer valve	5	0
Lavatory	Private	Faucet	1	1
Lavatory	Public	Faucet	2	2
Bathtub	Private	Faucet	2	2
Shower	Private	Faucet	2	2
Kitchen sink	Private	Faucet	2	2
Service sink	Public	Faucet	3	3

Notes

• NSPC WSFU values differ from IPC and UPC for the same fixture types.
• Select NSPC in System Structure to use these values automatically.

NSPC Pipe Sizing Guide

The National Standard Plumbing Code (NSPC) provides its own fixture unit values and sizing approach. Here is how Plumbing Booster implements NSPC-compliant pipe sizing.

WSFU Calculation Guide

Understanding WSFU is fundamental to plumbing design. This guide explains what WSFU are, how different codes define them, and how Plumbing Booster uses them for pipe sizing.