Sizing Plumbing Water System

A. Bhatia, B.E.


Course Outline

Plumbing water distribution systems are designed on the idea of the most probable peak demand loading, which reflects the worst-case scenario for a system. These types of systems require different considerations than large-scale water distribution networks. The difference is primarily attributed to uncertainty regarding the use of plumbing fixtures, hence uncertainty in demand loadings.

This 3-hour course provides comprehensive design methodology and underlying principles of plumbing water systems. This course addresses the design criteria for estimating potable water demand for residential and transitory use facilities. 

This course includes a multiple-choice quiz at the end, which is designed to enhance the understanding of the course materials.

Learning Objective

At the conclusion of this course, the student will:

Intended Audience

This course is aimed at students, architects, mechanical engineers, civil engineers, facility designers, health and environment professionals, energy auditors and anyone who wants a basic understanding of plumbing systems. 

Benefit to Attendees

This course will help professional engineers and designers gaining a basic understanding of plumbing systems and help conceptualizing design in the absence of any more appropriate information. 

Course Introduction

In today's buildings, all occupancies must be provided with a supply of potable or drinkable water that has enough volume and pressure to make it easily available.

Design of plumbing water system primarily requires estimating the water demand and selecting equipments associated with potable water system.

Supply plumbing includes all piping and related components from the water source to the fixtures.

The course is divided into four parts as follows:

Course Content

The course content is contained in the following PDF file:

Sizing Plumbing Water System

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Course Summary

The course presents the basic understanding of the fundamental concepts of plumbing water system. The model codes such as UPC, SPC, and IPC provide a simplified basis of estimating the potable water demand based on the number of plumbing fixtures.

The estimation of potable water demand is based on the probability theory that has been worked out to predict the mind-set or socioeconomic ethics of the consumers on water use. The fundamental piping design parameter, fixture unit count, is a rough (probable) estimate based on continuous vs. intermittent water demands in a great variety of occupancies, which is then used to estimate supply delivery rates, pipe diameters, and component capacities. The estimation of ‘non-residential’ water demand is based on the historical data published by American Water Works Association.

The recommended sizing of piping system is based on the pressure drop-velocity criteria. A standard engineering practice for pipe sizing is based on restricting pressure drop to 5 psi per 100 ft equivalent length simultaneous with velocity not exceeding 8 fps. The various other plumbing items such as pumps and storage tank selection should be based on the peak demand and maximum average day demand respectively.

Related Reading

Water Conservation

Water is available in abundance and therefore a little attention is paid to conserve the water. One tends to forget that there are costs associated with treating water and any wastage has direct impact on the energy and environment. Potable water systems are also disinfected to make it suitable for drinking. The regulating agencies are putting more and more emphasis on conserving water and in some states even enforcing restrictive covenants on the use of water. A 2-hour course titled "Water Conservation Tips" provide a glance to conservation practices.


Once you finish studying the above course content, you need to take a quiz to obtain the PDH credits.

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DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of PDHonline.org or any other person/organization named herein. The materials are for general information only. They are not a substitute for competent professional advice. Application of this information to a specific project should be reviewed by a registered professional engineer. Anyone making use of the information set forth herein does so at their own risk and assumes any and all resulting liability arising therefrom.