Water Supply

IPC Pipe Sizing Tables

IPC Table E104.1 minimum pipe sizes and Table E103.3(3) WSFU-to-GPM conversion for water supply sizing.

Introduction

The IPC provides two key tables for pipe sizing: Table E103.3(3) converts WSFU to GPM flow rates, and Table E104.1 specifies minimum pipe sizes for water meters, mains, and distribution piping.

IPC Table E103.3(3) - Supply System Demand (Flush Tank)

WSFU	GPM	WSFU	GPM	WSFU	GPM
1	3	20	19	200	60
2	5	30	23	300	75
3	7	40	27	400	85
5	9	50	30	500	95
10	14	70	35	1000	125
15	17	100	43	2000	180

IPC Table E104.1 - Minimum Pipe Sizes (Selected)

WSFU	Min Pipe Size	Max Length (ft)	Flow (GPM)
1	3/8"	50	3
2	3/8"	50	5
3	1/2"	60	7
5	1/2"	70	9
10	1/2"	80	14
20	3/4"	100	19
30	1"	130	23
50	1"	200	30
70	1-1/4"	250	35
100	1-1/4"	300	43
200	2"	400	60

Notes

• Table E103.3(3) has separate columns for flush tank and flushometer systems.
• The conversion is non-linear due to diversity factor.
• Table E104.1 values are minimums - velocity checks may require larger pipes.

IPC Pipe Sizing Guide

Step-by-step explanation of the IPC table-based pipe sizing method, from WSFU summation through flow conversion to final pipe selection using Table E104.1.

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.