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Philadelphia Water Department
Water and Drainage History Course

Module 7

Drainage for the City:
A brief history of sewers and stormwater drainage in Philadelphia

All images from the Philadelphia Water Department Historical Collection unless otherwise noted.
Clicking some images will open larger versions in a new window.

Mill Creek Sewer under construction at 47th Street and Haverford Avenue, 1883
Mill Creek in West Philadelphia was one of many creeks that was piped underground and made an integral part of the City's sewer system. For more information on the conversion of creeks to sewers, including a map showing locations of historic streams, visit www.phillyh2o.org/creek.htm.


Proper drainage is as important to the City's public health as the provision of pure drinking water. Sewers carry away excess rainwater, preventing flooding in streets and basements in all but the most extreme storms. They also carry disease-causing human and industrial wastes away from built up areas. In the City's present system, three treatment plants treat the sewage before discharging the effluent into the Delaware River. The treated effluent is cleaner than the river itself. The system has 3,000 miles of sewer pipes, ranging in size from 8 inches in diameter to 24 feet square.

Need for storm drainage

Managing stormwater runoff has been a public works necessity since the founding of Philadelphia in 1681, with the methods having changed only in their scope and the sophistication of their engineering. Houses were designed with gutters and downspouts to channel runoff away from property and into street gutters. As streets were laid out, low ground was filled in and high ground cut down, which allowed water in the gutters drain efficiently into the nearest natural stream without pooling up along the way. The City's first sewers, built around 1740, supplemented this system of surface drainage with underground pipes, commonly constructed of brick. These so-called "storm sewers” were considered a benefit to property owners, and in the 19th century citizens were often charged for part of the construction cost. For example, in Spring Garden in 1843, homeowners paid 63 cents per linear foot of property frontage when sewers were built.

Detail from 1848 plan showing inlets into the Pine Street sewer, and outlet (bottom of plan) through the City Wharf into the Delaware River. (City Archives of Philadelphia)

Plan of Pine Street Sewer, 1830
The "present surface" of the ground will be cut down in the process of building this sewer, with the final level of the street shown in the regular line below. Some of the soil cut away from the high ground will be used to fill the low ground at the outlet of the pipe, at the Schuylkill River. (
City Archives of Philadelphia)

Plan for regulation of Sassafras (Race) Street, 1819
The line at 34.2 is the drainage divide of this block, with stormwater flowing from there in the direction of the arrows down to the corners of Third and Fourth streets. (City Archives of Philadelphia)

Plan of drainage areas leading to various sewer inlets, early 19th century
Each colored area represents a small “watershed.” The numbers at the bottom of the plan are calculations of the various drainage areas, which helped determine how large to make the receiving sewers. Both sewers in this plan end in a stream—the Walnut Street sewer flowing into the tidal reaches of Dock Creek, and the sewer along 12th Street emptying into Shackaminsing Creek, which flowed into the marshlands of South Philadelphia. (City Archives of Philadelphia)

Plan and profile of proposed connection with the Delaware Seventh Street Sewer, extending from property of Samuel McGrath No. 215 Chestnut St. to a point in the main sewer on Seventh Street 104 feet north of Chestnut Street. By Samuel. H. Kneass, Philadelphia 20th Dec. 1850. (City Archives of Philadelphia)

Underground sewers were originally for stormwater drainage only. Starting around 1810, individual properties could make direct connections to city sewers as long as only water was put into the pipe; no sewage was allowed. Property owners had to petition the City Councils (there were two Councils at the time, the Select Council and the Common Council), and an ordinance was eeded for each connection. Even though connections were allowed, most properties still simply drained into the street, with the stormwater flowing away in the gutters to the inlets. Limited wastes were allowed into the sewers beginning in the 1830s. By the 1860s, such connections became a requirement, and the result were so-called "combined" sewers, carryng both stormwater and wastes from homes and businesses.

Privies: On-Site Disposal of Human Waste

Privies at 2976 Emerald Street, 1919
(City Archives of Philadelphia)

Early sewers only carried stormwater. Human wastes were collected in privy wells, and most commercial wastes were either thrown into street gutters or dumped into the nearest stream. Once the City began supplying water to citizens, fixtures such as bathtubs and water closets came into wider use. The wastewater produced by each household increased greatly. Privies, designed for mostly dry wastes, were unable to handle this increase, and regularly overflowed. In the early 1860s both human and commercial wastes were allowed into the City's sewers along with stormwater, creating the combined sewers still used in the old parts of the City. Considered a health hazard, privies were strictly regulated by the City's Board of Health. Homeowners were often cited for having “foul and overflowing” privies, and required to have them cleaned. Privies were gradually phased out as sewer lines were extended. One section of the 1915 regulations shown above reads, “This privy MUST be abandoned when Sewer is accessible.”

Cleaning privies was dirty, stinking work done by "nightmen," so-called because they were only allowed to do their work at night, when the deleterious effects of the odors they stirred up were deemed to have less chance of causing harm to human health. Privy cleaners were supposed to receive permits for the work from the Board of Health, although, as the following shows, this law was not always followed. In the first half of the 19th century the City of Philadelphia maintained one or more "poudrette pits," where the nightmen dumped the privy waste (also called night soil) and it was turned into an agricultural fertilizer.

Rules governing the sanitary maintenance of privy vaults and privy houses in the City of Philadelphia
(City Archives of Philadelphia)

Receipt for Privy Cleaning, 1885
(Courtesy of Tomlinson Family)

Covering polluted streams

Sewer under construction in Rock Run (a tributary to Tacony Creek) along the line of present-day Ashdale Street, 1922
(City Archives of Philadelphia)

Before the construction of sewage treatment plants in the 20th century, sewers simply emptied into the nearest stream, many of which became open sewers. Over time, most of the City's streams were encapsulated in huge pipes that became part of the sewer system. Putting the polluted streams underground eliminated serious health and aesthetic problems. Also, filling in the stream valleys over these sewers allowed the City's grid of streets to be extended without the expense of building bridges at every stream crossing.

Mill Creek once drained most of West Philadelphia. It was encapsulated in a sewer between 1869 and 1895. Parts of the Mill Creek Sewer (see construction photo at top of page) are 20 feet in diameter.

Dock Creek, badly polluted by waste from leather tanneries, was covered in two stages, in 1765 and 1785. Dock Street, in Society Hill, now meanders above a small part of the former creek bed.

Dock Creek (left side of image).
Detail from "Philadelphia in 1702", an engraving made in 1875

Little Tacony Creek, which once flowed through Frankford, had become an “open sewer” by the 1890s. Citizen outcry in 1899, spurred by The North American , a local newspaper, was met by a City plan to put part of the creek into a sewer that would run under a new street, Pratt Street. This sewer was not completed until about 1930.

The Aramingo Canal (dug in the 1850s along the course of a small Delaware River tributary, Gunner's Run) never made any money, and was converted into a sewer at the turn of the 20th century.

Aramingo Canal during sewer construction, 1900

Intercepting Sewers

An aqueduct, built in 1892, carried the City's first “intercepting sewer” over Cresheim Creek. Running along the Wissahickon Creek and Schuylkill River, this pipe “intercepted” the flow of sewers that had formerly entered those streams and polluted the City's water supply. Raw sewage in drinking water caused a variety of diseases, including typhoid fever, which killed thousands of City residents in the 1890s and early 1900s. In the 20th century, a citywide system of interceptors was built to protect streams from pollution and carry sewage to treatment plants.

Aqueduct over Creishem Creek, in the Wissahickon Valley, 1906
(City Archives of Philadelphia)

Extending the Sewers

Beginning in the late 19th century, the City tried to spur real estate development by extending its infrastructure-including streets, sewer lines, gas mains and water mains-into rural areas. Tax revenues generated by new construction often paid for the cost of the City's improvements within a few years. Larger sewers like those built in Bingham Street, near Tacony Creek, in 1921 and Devereaux Street in 1911 (see photos below), were custom-designed and built in place. For smaller, branch sewers the City manufactured standardized pipes. Workers performed load tests to ensure the pipes, once buried, would not collapse under the weight of the soil and traffic. In the photo below, a 36-inch pipe was loaded with 33,000 pounds for 14 days.

Bingham Street Sewer, 1921

Devereaux Street Sewer.
, Vol. IV, No. 6, June 1911)

Load test on Concrete Pipe 1914
(City Archives of Philadelphia)

Inspection and Maintenance

Inspection and maintenance have always been an important part of the City's management of its sewers. Modern technology has made it easier and safer to detect and fix problems without risking workers' health or lives. "Regulations for sewer inspectors and other persons engaged in sewerage work", an employee handout from 1908, recommends the following: "No manhole or sewer is safe to enter in which a lighted candle will not burn brightly, and in such cases fresh air must be admitted into the sewer until a steady light is obtained. All manholes or sewers must be tested in this way before any person can be permitted to enter, except that a light must not be used where there is any indication of illuminating gas in the sewer ." Today, gas detectors have replaced candles, and video cameras have partly replaced the need for human “sewer crawlers” to enter sewers.

Still photo from video sewer inspection

Treatment of Sewage: Planning & Research

On April 22, 1905, the Pennsylvania State Assembly passed “An act to preserve the purity of the waters of the state, for the protection of public health.” This law prohibited municipalities from building new sewers that would discharge untreated sewage into streams. The goal was to have all the State's sewage treated before discharge, to prevent disease-causing micro-organisms found in sewage from entering drinking water supplies. Such bacteria and viruses were known to cause many diseases, including typhoid fever. This virulent disease killed thousands of Philadelphians in annual epidemics in the 1890s and early 1900s.

Writing in 1905, G. Everett Hill claimed, rightly so, that proper disposal of our wastes was a benchmark of a civilized society: "Our lives have grown very complex. Things which our ancestors never saw are necessities to-day; and what we see in Nature's storehouse and want, we do not hesitate to appropriate. We kill the cattle, we cut down the forests, we tear the iron and coal from the bowels of the unwilling earth; we even appropriate the air and sunshine and use them as slaves to drive out motors and paint our pictures. All this is progress, and a certain measure of progress in acquisition is called civilization. But acquisition and use must always be followed by consumption and rejection of the products of consumption. Our track of progress is really a trail of desolation strewn with ashes, excrement and rubbish....Can we rightly boast of national civilization when less than 4 per cent. of the communities in our country have adopted means for the hygienic disposal of filth; and when the sixth city of the land is riddled--under buildings as well as under yards and streets--with cesspools, whose overflow babbles noisily and noisomely in the street gutters?" [G. Everett Hill, "The bacterial disposal of sewage." Journal of the Franklin Institute, 159:1 (Jan.1905) 1-16.]

Spring Garden Sewage Experiment Station

Pennypack Sewage Treatment Works

A sewage treatment experiment station was set up near the old Spring Garden pumping station (along the Schuylkill near the Girard Avenue Bridge), where drinking water filtration experiments had been conducted several years earlier. As a result of this work, the City's first treatment plant was built in 1912 to keep the raw sewage of several municipal institutions out of Pennypack Creek, which emptied into the Delaware River within reach of water intake points at the Torresdale pumping station. As the Pennypack Works was a prototype the much larger Citywide sewage treatment system then being developed, its operation and performance was closely scrutinized and extensive documentation is available in PWD annual reports from the period.

The Pennypack plant began operations on December 1, 1912, and ceased operations on December 13, 1930, when the construction of an intercepting sewer along the Delaware River allowed the routing of the sewage farther south, to Northeast Sewage Treatment Works, completed in 1923. [Bureau of Surveys Annual Report for 1930, manuscript, p. 41-1930 (p.10), PWD Historical Collection]

After nearly ten years of study, including first-hand inspection by City engineers of sewage treatment works in this country and in Europe, Philadelphia, in 1914, published a comprehensive Report on the Collection and Treatment of the Sewage of the City of Philadelphia. This plan included miles of intercepting sewers, designed to keep sewage out of the rivers and carry it to three proposed treatment plants. This extensive system took over 50 years to complete. Today's system, with many upgrades and additions, still conforms to the outlines of the 1914 plan.

1914 Plan for Collection and Treatment of Sewage
(For a high-resolution color version, visit this link.)

One reason the new system took so long to complete was the cost, which was more than the City had ever spent on any public works project. Also, with drinking water filtration and chlorination in place by 1912, the risk of using the sewage-laden rivers as sources of drinking water was greatly reduced. This made the construction of expensive sewage treatment plants less of a priority.

World events also conspired to delay the system's completion. During the Depression, greatly reduced City tax revenues brought most public works to a standstill. During the two World Wars, all non-essential construction was put on hold as manpower and critical materials such as steel were diverted into the war efforts. In the meantime, sewers continued to dump human and industrial wastes directly into the City's streams. The July 15, 1918 photographs below show the Allegheny Avenue Sewer emptying into the Delaware River at Pier, while on the same day, on the other side of the pier, swimmers enjoy a refreshing (?) dip

Above: Allegheny Avenue Sewer at Pier 126, Delaware River July 15, 1918
Below: Swimmers at Pier 126, Delaware River July 15, 1918
City Archives of Philadelphia

In 1923 the City did complete one of the three planned treatment plants. The Northeast Sewage Treatment Works and its intercepting sewers replaced the Pennypack plant, helping protect the waters around the drinking water intake at Torresdale. But this single plant could not reverse the overall tide of pollution. By 1929, a City engineer declared that the lower Schuylkill River was no better than an open cesspool, receiving the wastes of roughly 500,000 people via the Schuylkill interceptor sewer. In the 1940s, the Delaware River's pungent smell reached as far inland as City Hall, and the low levels of oxygen in the water meant little or no aquatic life. Runs of shad, an anadrmous (or migrating) fish for which Philadelphia was once famous, came to an abrupt end, as the fish hit the dead zone in the river around Philadelphia and were unable to return upstream to spawn. DR_NESTWGenlPerspective1918.jpgPlan, Northeast Sewage Treatment Works, 1918

Just as sewers helped spur City growth at the turn of the 19th century, the lack of sewers in the City's rural and suburban areas during World War II meant a halt in real estate development and unpleasant conditions for residents. Burholme's “marching mothers” went to te Mayor's office, and then on to Washington, D.C., to complain of overflowing cesspools and dirty dishwater running in the streets.

Post World War II: Sewage Collection and Treatment System Completed

Federal loans, along with revenue from a new “sewer rent” implemented in 1944, allowed the City to complete the sewage collection and treatment system outlined in the 1914 plan. Two new treatment plants were constructed (Southeast and Southwest), and the Northeast plant was enlarged and modernized.

Southwest Sewage Treatment Plant under construction in 1949
(City Archives of Philadelphia)

City Officials Tour New Interceptor Sewer, 1953

Southeast Sewage Treatment Works Centerfold of Brochure, 1955

Northeast Sewage Treatment Works Brochure, 1951

Work continued on the intercepting sewers into the 1960s. In new areas of the City, separate sewers were built, carrying stormwater and sewage in separate pipes. The photograph below shows the last gasp of the original Schuylkill Interceptor, which since the 1880s had diverted sewage from the Schuylkill River above the Fairmount Dam and dumped it, untreated, below the dam. On this day in 1956, the sewer's flow was diverted into a new interceptor that carried the wastes to the Southwest Sewage Treatment Plant.

Last gasp of the Schuylkill Interceptor December 20, 1956

Treatment of Sewage: Modern Day System

Fishing in the Schuylkill
(Link Harper, Philadelphia Dept. of Records)

The first Earth Day in 1970 marked the start of a global environmental consciousness. The chartering of the Environmental Protection Agency (EPA) later that year represented a new federal commitment to preserving the environment. Congress passed the Federal Water Pollution Control Act (also known as the Clean Water Act) in 1972. This complex law required that every stream meet designated water quality standards based on type of use. To meet these new guidelines, the City began an upgrade of its sewage treatment processes that took 15 years and cost more than $1 billion.

Wastewater Treatment Process

The treatment of wastewater--sewage, stormwater or their combination--involves a number of steps.

Preliminary treatment (steps 1, 2 and 3) removes the largest and heaviest objects from the water.
1. Collecting and Pumping: Sewers collect household wastes and stormwater runoff from all sections of the city and deliver it to one of three wastewater treatment plants.
2. Screening: Wastewater is pumped into the plant, passing through a bar screen (either before or after the pumping) that catches the biggest objects including trash.
3. Grit Removal: The flow of the wastewater slows as it passes into the next tank. The slightly slower flow allows grit (sand and gravel) to settle to the bottom of this tank.

Primary treatment (step 4) removes all the particles that will settle out of the wastewater through gravity.
4. Primary Sedimentation: The flow of wastewater slows even further as it moves into the next tank, where smaller suspended solids such as toilet paper fibers sink to the bottom.

Secondary treatment (steps 5 and 6) removes dissolved pollutants and suspended solids too small to settle out through gravity.
5. Aeration and Biological Reduction: Microorganisms, or “activated sludge,” are introduced into the wastewater and supplied with air; these microbes consume the remaining pollutants.
6. Final Sedimentation: The microorganisms become heavy and sink to the bottom of the tank, where they are collected and reused in the process.

Disinfection and discharge (steps 7 and 8).
7. Disinfection: Before it is discharged into the Delaware, wastewater is treated with bleach (sodium hypochlorite) to kill any disease-causing pollutants that were not eaten by the microorganisms. 8. Effluent Discharge: As treated wastewater flows through the effluent channel, sodum hypochlorite is dissipated. The treated ewastewater is then returned to the river, cleaner than the river water itself.

Throughout the treatment process, treatment plant operators control the flow of wastewater by computers. Each plant has up to six channels to handle the flow of incoming wastewater. The sludge collected from the primary and secondary treatment processes, in the past dumped in the ocean, was for many years composted in Southwest Philadelphia (in an area between the Platt Bridge and I-95 bridge, as shown in the photo) and turned into a product called Earthmate. Sludge recycling isposal has now been contracted to a private company.

Untreated, or raw sewage, is 99.99% water, but the impurities in the remaining .01% can cause illness or death and render a stream devoid of life. Sewage treatment has meant the rebirth of Philadelphia's rivers. Decomposing sewage once consumed most of the oxygen in the rivers, leading to the death of fish and other aquatic life. Now, with sewage removed from the rivers, oxygen and fish have returned. Over the years, all three of the City's sewage treatment plants have received gold awards by the Association of Metropolitan Sewerage Agencies.

Jar of raw sewage before treatment, 2000


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