Print this page Print this page

Population Projections

Paul Graves, P.E.

Course Outline

This one-hour online course provides an introduction to methods of projecting population growth or decline. Future population size is a key parameter in designing facilities such as domestic water and wastewater treatment plants and municipal solid waste landfills.

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:

Course Introduction

In designing facilities such as public water treatment plants, domestic wastewater treatment plants, and municipal solid waste landfills, engineers generally rely on typical rates of water use, wastewater generation, and solid waste generation. Some common rates in the U.S. are 150 gallons per day per capita (gpdc), 100 gpdc, and 4 pounds per day per capita, respectively.

A common denominator in these rates is "per capita", that is, "per person". Hence, in order to design these types of facilities one must estimate the total number of capita to be served. Furthermore, because these types of facilities are typically designed to serve a geographic area for decades, the designer must make use of population projections, whether available from other sources or prepared by the design team.

This course provides an overview of population projection techniques, including mathematical and graphical methods. Data sources and other considerations are addressed to provide an understanding of the uncertainties involved and a basis for evaluating trends.

Course Content

The introduction and the course content are in a PDF file (4882 KB) Population Projections. You need to open or download this document to study this course.

Course Summary

A number of techniques are available for projecting future population changes. Simple approaches as described above are commonly used by engineers to estimate the future population of a given area as necessary for designing certain public facilities. Even when the population projection is available from others, it is important for engineers to consider the uncertainty in the estimate. The amount of uncertainty should be reflected in the range of potential future populations considered in the design.

Additional Resources

Population data is available from numerous agencies and other sources.  Selected references are provided at the links below.  Additional information may be found by performing an Internet search.

U.S. Census Bureau

United Nations Population Division

Ameristat by the Population Reference Bureau



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

Take a Quiz

DISCLAIMER: The materials contained in the online course are not intended as a representation or warranty on the part of 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.