NISTIR 7158

Major U.S. Cities Using National Standard Fire 

Hydrants, One Century After the Great Baltimore 

Fire 

Momar D. Seck and David D. Evans 

Fire Research Division 

Building and Fire Research Laboratory 

Gaithersburg, Maryland 20899 

United States Department of Commerce 

Technology Administration 

National Institute of Standards and Technology 
NISTIR 7158

Major U.S. Cities Using National Standard Fire 

Hydrants, One Century After the Great Baltimore 

Fire 

Momar D. Seck and David D. Evans 

August 2004 

Fire Research Division 

Building and Fire Research Laboratory 

National Institute of Standards and Technology 

Gaithersburg, MD 20899 

U.S. Department of Commerce 

Donald L. Evans, Secretary 

Technology Administration

Phillip J. Bond Under Secretary for Technology

National Institute of Standards and Technology 

Arden L. Bement, Jr., Director
TABLE OF CONTENTS 

List of Tables......................................................................................iv 

List of Figures......................................................................................v 

1. Abstract....................................................................................1 

2. Background................................................................................2 

3. The 1904 Great Baltimore Fire.........................................................2 

4. The establishment of a National Standard Hydrant..................................3 

5. The 1991 Oakland Hills Fire............................................................5 

6. Assessment of the Situation.............................................................5 

7. Acknowledgements.......................................................................9 

8. References.................................................................................9 
LIST OF TABLES 

Table 1: Tabulation of Fire Hydrant Connection Specifications for the 48 largest cities in the 

 U.S.
LIST OF FIGURES 

Figure 1: Pictures of one fire engine during the Great Baltimore fire and a 1904 Baltimore fire 

 hydrant. 

Figure 2: Pictures of Standard Fire Hydrants. 

Figure 3: Histogram of the number of cities with the different kinds of connections. 
Major U.S. Cities Using National Standard Fire Hydrants, 

One Century After the Great Baltimore Fire 

Momar D. Seck 

David D. Evans 

1. Abstract 

Fire equipment responding from different cities to the Great Baltimore Fire in 1904 were 

hampered or rendered useless by the incompatibility of hose and fire hydrant connections. After 

the Baltimore fire, a national standard for fire hydrant connections was adopted by the National 

Fire Protection Association. One-hundred years after the Great Baltimore Fire, 18 out of the 48 

most populated U.S. cities have installed national standard fire hydrants. Specifications are 

given for the hose connections on hydrants installed in those 48 cities. 

Key Words: fire fighting; fire hoses; fire hydrants; Great Baltimore Fire; Oakland Hills Fire; 

pumper connection; standards; steamer connection 
2. Background 

When fire hoses were first manufactured, the threads used to couple them differed among all the 

manufacturers. The same is true with the fire hydrant connections. Since the first fire hydrant 

was designed in 1817 by George Smith [1], each design, including hose connection threads, was 

patented by its manufacturer. Differences in hose connections on the hydrants, both diameters 

and threads, were part of the design that protected manufacturers from competition. Cities with 

different hydrant suppliers had fire fighting water supply systems with connections that were 

incompatible with those in other, sometimes neighboring, communities. History demonstrates 

that in major urban fires, the inability of fire fighting apparatus from other areas to utilize the 

water supply, because of incompatible hose connections, was a contributing factor to increased 

fire damage. 

3. The Great Baltimore Fire 

The lack of uniform threads is commonly cited as a factor in the massive destruction of the Great 

Baltimore Fire that started on Sunday afternoon, February 7th, 1904. The fire is believed to have 

been started by a cigar or cigarette that fell into the basement of the John Hurst & Company 

building [2]. 

Engine companies from Washington, DC, transported by train, arrived in Baltimore to assist in 

fire fighting a few hours after the fire started. Unfortunately, their hoses would not fit Baltimore 

hydrants due to the difference in threads. The fire continued to claim block after block of 

buildings in the Baltimore business district as more fire companies arrived from surrounding 

cities and counties, Altoona, Annapolis, Chester, Harrisburg, New York, Philadelphia, 

Wilmington, and York. Some of the responding fire companies’ hoses fit the Baltimore hydrant 

connections; others did not [3]. 

The Great Baltimore Fire was finally put out thirty hours after it started. Despite the 1,231 

firefighters, 57 engines, nine trucks, two hose companies, one fireboat, and one police boat used, 

the fire claimed 1,526 buildings in an area of seventy city blocks. A total of 2,500 businesses, 
banks, etc were lost in the fire. Fortunately there was only one life lost. Firefighter James 

McGlennen died few days after the fire of injuries sustained while fighting the fire [2]. 

 

 (a) (b) 

Fig. 1: (a) Picture of one fire engine battling the fire during the Great Baltimore fire. (b) Closeup of the lower right corner of picture 1a showing a 1904 Baltimore hydrant. The tallest object 

in the background is the cover of the hydrant that is right in front of it. The cover is removed to 

expose the hose connection of the fire hydrant. (Courtesy of the Baltimore Sun)[4] 

4. The Establishment of a National Standard Hydrant 

In the process of establishing fundamental standards and planning basic research programs, the 

National Bureau of Standards (NBS), now the National Institute of Standards and Technology 

(NIST), encountered in late 1904 the same incompatibility of hose couplings that firefighters had 

during the Baltimore fire. One evening, while trying to put out a small fire, Franklin Durston, a 

NBS employee, found out that the hoses in the North and South Buildings of NBS could not be 

coupled because of different threads. 

Several months prior to the NBS fire, a study by Albert Merrill, an NBS employee, revealed that 

there were about 600 sizes and variations in fire-hose couplings across the country [3]. The 

National Board of Fire Underwriters and the National Fire Protection Association (NFPA) 

advocated a national standard of threads for hoses and fire hydrant outlets before the Great 
Baltimore Fire, but it received little support. In 1905, an NFPA committee established a standard 

diameter and number of threads per inch for hose couplings and fire hydrants∗

. The standard was 

adopted by the National Fire Protection Association, the National Board of Fire Underwriters, 

the Associated Factory Mutual Fire Insurance Companies, the International Association of Fire 

Chiefs, the American Water Works Association and many other organizations [5]. The 1905 

NFPA Standard specified that fire hydrants have 2.5 inch-hose connection nozzles with 7.5 

threads per inch, and 4.5 inch-engine suction (or pumper) connection nozzles with 4 threads per 

inch [5]. These specifications remain as the current standard for fire hydrants. By 1914, only 

287 of the 8,000 cities and towns in the US had fire-hose couplings and hydrant outlets 

conforming to the standard. By 1917, 897 cities agreed to adopt the standards, but only 390 were 

using them. Every year the number of cities with standard hydrants and fire-hoses was 

increasing. By 1924, the number was 700 cities. Some of the cities made the change only after 

they experienced their own major fire. 

5. The 1991 Oakland Hills Fire 

On Sunday, October 20, 1991, the nation experienced another urban fire disaster in Oakland, 

California, the worst involving loss of lives and properties since the great San Francisco 

earthquake and fire of 1906 [6]. The fire started in a wooded area above State Highway 24 near 

the Caldecott Tunnel [6]. The fire grew rapidly due to the high speed and dry “Santa Ana” 

winds from the east. Engine companies from the surrounding fire departments were called 

immediately. Firefighters and commanders encountered many problems, among them 

incompatibility of hose and hydrant connections. Those engines having the 2.5 inch (standard) 

hose couplings could not connect to the 3 inch couplings on Oakland fire hydrants at the time. 

The fire claimed the lives of 25 people including a police officer and a firefighter [7]. In 

 

∗

 Fire hose and couplings have historically and are still widely expressed using units of inches (diameter) and 

threads per inch. Since most users of fire hose are familiar with these traditional units and for the sake of clarity, 

inch-based descriptors are used throughout this report rather than converting traditional units to SI units. 
 

(a) (b) 

Fig. 2: Pictures of Standard Fire Hydrants (a) Side view of a three-nozzle hydrant showing the 

main nozzle or pumper connection (41⁄2” diameter with 4 threads per inch), and one of the two 

small hose nozzles or hose connections (21⁄2”diameter with 71⁄2 threads per inch), (b) Front view 

of a two-hose and one- pumper nozzles hydrant. (Reuter: Mike Hassler) 

addition, about 150 people were injured, and almost 2,450 single-family homes and 437 

apartments were destroyed. The cost of the damage was approximately $1.5 billion [7]. After 

the fire all of the fire hydrants were replaced with hydrants using national standard specifications 

for the hose connections. 

6. National Standard and Non-standard Hydrants in Use 

It is surprisingly difficult to assess the specifications for fire hydrants in use in major U.S. cities 

without direct on-site measurement. No central source of hydrant specification data exists. After 

many contacts with fire departments, fire marshals, and local government authorities around the 

country, it appears that the best sources of specification data are records kept by manufacturers 

of fire hydrants. The hydrant specifications of most of the cities in Table 1 were obtained with 

the cooperation of Mueller Company, a major fire hydrant manufacturer. The company agreed 

to share information from its records for this study. For some of the cities not included in Muller 

Company records, individual contacts with fire departments and departments of water services or 
public works were made to determine the specifications. In addition, chapter members of the 

Society of Fire Protection Engineers (SFPE) volunteered to provide hydrant connection 

measurements in their areas of the U.S. where needed. 

In order to verify the hydrant specifications of every city in Table 1, a letter and a copy of Table 

1 were sent to the fire chief of each city in the table. Each chief was asked to verify the hydrant 

specifications of their city and contact NIST to either confirm or correct the data in the table. 

Some city fire departments had to be contacted again by means of emails and phone calls. The 

responses helped us make some corrections to the original data. The verified data is listed in 

Table 1 below. 

Most of the major cities in the U.S. do not have standard fire hydrants and fire-hose couplings. 

In fact, only 18 out of the 48 most populated cities have both small hose and pumper connections 

on fire hydrants that comply with the NFPA standard. A standard fire hydrant has two 2.5 inchhose connection nozzles with 7.5 threads per inch, and one 4.5 inch-pumper connection nozzle 

with 4 threads per inch. The hose connection nozzle, compared to the pumper connection 

nozzle, has a lower discharge pressure and can be used directly to fight fires. The pumper 

connection nozzle, on the other hand, is connected to the engine that provides water to hoses 

mounted on the fire truck. Among the cities having national standard fire hydrants is Baltimore 

that progressively standardized its hydrants after the great 1904 fire. Oakland, California also 

changed its hydrants to national standards after it experienced the disastrous fires in 1991. 

About 40 major cities have at least national standard hose connections on their hydrants. Most 

of these cities have a 4 inch-pumper connection with 4 threads per inch on their hydrants instead 

of the national standard pumper connection. The hydrants of these cities comply partially with 

the national standard specifications. Other cities, such as New York, Oklahoma City, and New 

Orleans have standard pumper connections (or steamer connections) and non-standard hose 

connections. The remaining 5 of the 48 cities have no standard connections (neither a pumper 

nor a hose connection) on their hydrants. Among those cities is Chicago, IL, which has only 4.5 

inch-pumper connections with 6 threads per inch. The hydrants in Phoenix, AZ have two 2.375 

inch-hose connections with 6 threads per inch and one 3.75 inch-pumper connection with 
Hose connection Pumper Connection 

City 

(greatest to least populated) 

Diameter 

(inch) 

NS = 2 1⁄2 

Thread 

(threads/inch) 

NST= 7 1⁄2 

Diameter 

(inch) 

NS = 4 1⁄2 

Thread 

(threads/inch) 

NST = 4 

New York City, NY 2 3

/8 8 NS NST 

Los Angeles, CA NS NST 4 4 

Chicago, IL - - 4 1⁄2 6 

Houston, TX NS NST NS NST 

Philadelphia, PA NS NST NS NST 

Phoenix, AZ 2 1⁄2 6 4 6 

San Diego, CA NS NST 4 4 

Dallas, TX NS NST 4 4 

San Antonio, TX NS NST 4 4 

Detroit, MI NS NST 3 3⁄4 6 

San Jose, CA NS NST 4 4 

Indianapolis, IN NS NST 4 1⁄2 6 

San Francisco, CA 3 & 3 1⁄2 3 3 & 3 1⁄2 3 

Jacksonville, FL NS NST NS NST 

Columbus, OH - - 4 6 

Austin, TX NS NST 4 6 

Baltimore, MD NS NST NS NST 

Memphis, TN NS NST 4 7 

Milwaukee, WI NS NST NS NST 

Boston, MA NS NST NS NST 

Washington, DC NS NST 4 4 

El Paso, TX NS NST 4 6 

Seattle, WA NS NST 4 6 

Denver, CO NS NST 4 1⁄2 6 

Nashville-Davidson, TN NS NST NS NST 

Charlotte, NC NS NST 4 6 

Fort Worth, TX NS NST 4 4 

Portland, OR NS NST NS NST 

Oklahoma City, OK 2 1⁄2 6 NS NST 

Tucson, AZ NS NST NS NST 

New Orleans, LA 2 1⁄2 6 NS NST 

Las Vegas, NV NS NST 4 4 

Cleveland, OH 2 1⁄2 8 4 1⁄4 6 

Albuquerque, NM NS NST NS NST 

Kansas City, MO NS NST 4 4 

Virginia Beach, VA NS NST NS NST 

Atlanta, GA NS NST NS NST 

Sacramento, CA NS NST NS NST 

Oakland, CA NS NST NS NST 

Mesa, AZ NS NST NS NST 

Tulsa, OK NS NST 4 4 

Omaha, NE NS NST NS NST 

Minneapolis, MN NS NST NS NST 

Miami, FL NS NST 4 7 

Colorado Springs, CO NS NST 4 1⁄2 6 

St. Louis, MO NS NST NS NST 

Wichita, KS NS NST 4 4 

Santa Ana, CA NS NST 4 4 

Table 1: Tabulation of Fire Hydrant Connection Specifications for the 48 largest cities in the 

U.S. (Cities with national standard hydrants in Bold font) 
6 threads per inch. The city of San Francisco, CA, has two different hydrant designs. One 

design is a low-pressure hydrant with two 3 inch outlets with 3 threads per inch. The second 

design is a high-pressure hydrant with three 3.5 inch outlets with 3 threads per inch. The city of 

Columbus, OH, has hydrants with only 4 inch-pumper connections with 6 threads per inch. 

Cleveland, OH, has hydrants with two 2.5 inch-hose connections with 8 threads per inch and a 4 

inch-pumper connection with 6 threads per inch. Hydrants installed in fire districts outside of 

but near major cities are generally national standard. Despite the great variety of hydrant 

designs, adjacent fire districts can be called upon for mutual assistance in case of a major fire. 

Fire districts next to areas with different hydrant specifications carry adaptors to their equipment 

to connect to a variety of hydrants. For example, the fire districts near the Maryland/District of 

Columbia line carry adaptors because DC hydrants have 4 inch-pumper connections while the 

surrounding Maryland counties have national standard hydrants. 

Using the data in Table 1, Figure 3 below shows an overview of the extent to which the largest 

48 cities in the U.S. have adopted the national standard specifications for fire hydrants. 

0

5

10

15

20

25

30

35

40

45

Standard Fire

Hydrants

Hydrants with

Standard Hose

connections

Hydrants with

Standard

pumper

connections

Hydrants with

No standard

connections

Number of cities

Figure 3: The number of cities with the different kinds of connections. 
7. Summary 

This study reveals that 100 years after the Great Baltimore fire many of the major cities in the 

United States do not have national standard hydrants. Although all hydrants use standard pipe 

diameter and thread combination, the sizes are not always in agreement with the national 

standard for hydrant connections. Almost all hydrants have national standard hose line 

connections (smaller diameter outlet). Most major cities do not have national standard pumper 

connections (larger diameter outlet). Today, it is common for fire engines to carry adaptors that 

make connections with all hydrants in areas where equipment may be used. 

8. Acknowledgements 

We would like to acknowledge the major contribution of Randy Molby from the Mueller 

Company in Decatur, IL. Mr. Molby provided the hydrant specifications of most of the cities in 

Table 1. We would like to thank Morgan Hurley and all the SFPE members who helped us 

obtain hydrant specifications of some of the cities in Table 1. We also want to thank Mike 

Hassler of the Milwaukee School of Engineering for the pictures of fire hydrants, Joelle M. 

Fishkin from the International Association of Fire Chiefs (IAFC) for the assistance in contacting 

fire chiefs of all the cities in Table 1. We greatly appreciate the input of all the fire departments 

and city water services. 

9. References 

1. Strata Magazine: http://fifth-letter.com/strata/issue2/exhibit/hydrantintro.htm 

2. www.ezl.com/~fireball/disaster10.htm, August 20, 2004 

3. MEASURES FOR PROGRESS: A HISTORY OF THE NATIONAL BUREAU OF 

STANDARDS, Rexmond C. Cochrane, 1966 (Pages 84-86)

4. The Baltimore Sun, Baltimore, Maryland 

5. N.F.P.A. HANDBOOK of FIRE PROTECTION, Crosby-Fiske-Foster, Tenth Edition (pages 

693-697) 1948 

6. www.sfmuseum.org/oakfire/overview.html, August 20, 2004 

7. www.firewise.org/pubs/theOaklandBerkeleyHillsFire/abstract.html, August 20, 2004 

8. www.firehydrant.org, August 20, 2004