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Sewers in the Neighborhood

There are very few monuments to engineers in the City of Philadelphia, and most are in our near-neighborhood. The statue of Matthias Baldwin on the north apron of City Hall is one, although he is also honored there for being a good citizen and a philanthropist. One of the two fountains on Eakins Oval across from the Philadelphia Museum of Art is dedicated to John Ericsson, a mechanical engineer, designer of the USS Monitor ironclad ship, and inventor of the screw propellor for ships. Behind the Art Museum is a bust of Frederick Graff, who would be today considered a civil engineer for his design of the magnificent water works that operated in the 19th century. The state historical marker for Frank Piasecki at 1937 Callowhill Street honors the mechanical/aviation engineer who had his first shop there. One could argue that Thaddeus Kosciuszko’s monument at 18th and the Ben Franklin Parkway is such a monument, since Kosciuszko was a military engineer. This article examines those monuments that lie underneath our feet and give honor to nameless civil engineers.

The Philadelphia Water Department has three drinking water treatment plants and more than 3,000 miles of water mains. The history of these was discussed in our article here.  This article will look at the exit of water, both sewage and rain water, from our neighborhood. In Philadelphia there are approximately 3,000 miles of sewer lines, 79,000 stormwater inlets, three sewage treatment plants, 175 combined stormwater outflow (CSO, combined sewage and stormwater) regulating chambers, 164 CSO outfalls, and more than 450 stormwater outfalls. This article will look at how the Baldwin Park neighborhood fits into this engineering accomplishment.


I couldn’t find a good image of outhouses in our neighborhood, but this is an image of the 400 block of North Fairhill Street, from the Philadelphia Water Department (PWD) website. There are seven outhouses lined up in the alley.

Before Sewage Pipes

When animal and human populations were small and dispersed, leaving waste wherever it fell caused little hygiene risks. For example, it is thought that there was a human population bottleneck 70,000 years ago during which time there were only between 1,000 and 10,000 humans worldwide. In addition, populations then were non-sedentary hunters and gatherers. When a living site became overly contaminated with waste, the group moved on to a fresh site.

Ten thousand years ago, human groups began to settle down in one place to farm and raise domesticated animals. Concentrations of waste occurred. Animal waste, and sometimes human waste, would be used as a crop fertilizer. The more enlightened would dig pits for solid human waste to allow slow seepage of fluid components into the surrounding soil, with the soil filtering out contaminants before the waste water met the ground water.  Although the germ theory of disease was well in the future, the evolutionary adaptation of detecting and avoiding the foul smell of feces turned those so adapted into survivors. Their aversion to fecal odors lessened their risk of acquiring fatal fecal-borne diseases like cholera and typhoid fever.

As cities developed, these pits became more prominent and regulated. The privy, a hole dug in the ground behind the house, was lined by bricks or wood to prevent collapse and also to allow fluid seepage out of the pit. The privy pit was also called a “necessary,” and if a structure was built for privacy around the pit it was called an outhouse. Ben Franklin had an indoor “water closet,” a toilet with a pipe connected to the outdoor brick-lined privy pit. Flushing was done manually by pouring water into the toilet or via a flush tank nearby. These indoor toilets became more common among the affluent in Philadelphia in the 1840s.


One of the more famous privy pits in Philadelphia.

Many of the streams that criss-crossed Philadelphia in 1682 were used as convenient waste disposal sites throughout the 18th century and had become open sewers. In the 19th century most of these streams were placed underground in arched tunnels, essentially large pipes. The rationale was threefold:

  • Bury the foul miasmas that were believed to cause disease at that time;

  • Since the streams already flowed to the Schuylkill and Delaware by gravity, putting the streams in pipes allowed a cheap gravity-flow sewer system;

  • Getting rid of the valleys created by these streams made a neat grid on which real estate developers could more profitably build and sell.


The creeks in our neighborhood that disappeared are noted in our article here.


Portion of the 1802 Varle map. North is at the top.

Minnow Run is a small stream that arises from a spring between Bush Hill and Springettsbury Manor. This would join another branch and flow south and west into the Schuylkill River at Mulberry (now Arch) Street. It would be culverted sometime after 1831, the last time it appears on maps.

New houses built on streets with a sewer line were required to connect with the sewer starting in 1866. The Philadelphia Board of Health regulated the existing privies. When near full, or when instigated by the old-timey equivalent of 311 calls to the Board from neighbors, one of several dozen licensed privy cleaners would remove the solid waste. They usually worked at night, to minimize neighbors’ exposure to the noxious odors, and were therefore called “night men.” Their product was “night soil.” This would be deposited in pits outside the city, treated with charcoal powder and gypsum to reduce the odors, and when dried was sold as fertilizer.

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Portion of 1901 Bromley map

The map shows the yellow (wood frame) structures behind most of the brick (pink) houses in what is now Baldwin Park. Tatlow Street no longer exists. Hamilton Street runs left to right on the top of the map, and no longer exists on this block. 19th Street runs vertically on the left.

There were still privies on houses in the neighborhood at least as late as 1950, according to Sanborn insurance maps.

Houses at this time without a wood-frame outhouse in back may have had indoor plumbing connecting to city sewers; or had brick outhouses; or had indoor toilets flushed into a privy pit behind the house, like Ben Franklin.

Around the time of this map Bridget Carey (see the story of the alleged arsenic murderer in our article here) lived at 1842 Hamilton Street, at the top of this map, with her only living child and ten boarders. Twelve residents; one privy seat out back. Toilet seats rarely got cold. It would be interesting to sample the soil in the northwest corner of the park to check for residual arsenic from outhouse residues.

Sewer Pipes, but No Sewage Treatment

In the decades after 1890 the city pushed to hook all buildings up to sewer lines. In 1854, at the time of the consolidation of the City and County, there were 30 miles of sewer pipes. By 1899, there were 800 miles of sanitary sewer pipes (from homes) and stormwater sewer pipes in the city. This took care of the problem of digging out privies, but created the problem of increased river pollution since these early sewers emptied directly without treatment into the Delaware or Schuylkill Rivers and their tributaries.


Portion of a 1902 map showing sewer mains in the neighborhood. The 6-foot-diameter Callowhill Street pipe and the 4-foot-diameter Wood Street pipe flowed west emptying directly into the Schuylkill River. The Main Intercepting Sewer runs along the east side of the Schuylkill River at top left. This intercepting sewer collected drainage from the 500,000 residents living above Fairmount Dam and prevented it from flowing into the river above the Belmont and Queen Lane intakes.


This photo was taken during the 1898 realignment of the sewers for the construction of the Callowhill Cut, as discussed in our article here. The tunneled sewer under Callowhill Street was six feet in diameter and 2,953 feet long. The only near catastrophe in this project was when the tunnel being dug under Callowhill Street collapsed at 19th Street due to the old sewer above the tunnel rupturing and filling the lower tunnel with stormwater and sewage.

Photo credit here.


Manhole covers allow access to the sewer systems below. This cover, in front of the Tivoli Condominiums on 19th Street, was made locally at the Samuel J. Cresswell Iron Works at 23rd and Cherry Streets. The business functioned there from 1873 through 1950. That factory building was torn down in 2018 and luxury townhomes on that site now stand directly across 23rd Street from the Giant supermarket store.

As discussed in our article on the water supply in our neighborhood, the City began buying up properties along the Schuylkill River in 1856 to convert riverside properties from slaughterhouses and industries into park land. This measure lowered the risk of fecal-borne diseases acquired from the drinking water, but still the bacterial diseases typhoid and cholera continued to kill Philadelphians. Louis Pasteur’s germ theory of disease was finally being accepted in the late nineteenth century, and Joseph Lister and others demonstrated methods to limit the disease impact of microorganisms. By 1909 the city was filtering all the river water before pumping it out to the residents. By 1914 all the drinking water was chlorinated. Disease numbers dropped precipitously. There are now three potable water treatment plants where sand filtration and chlorination transform river water into tap water.

Sewage Treatment Plants (Water Pollution Control Plants)

The river water in the river itself was still befouled by sewage flowing untreated into the rivers. The decomposition of this raw sewage consumed the oxygen in the water, leaving none for animal life like fish. For example, an interceptor pipe that ran from Shawmont down the east side of the Schuylkill River carried the waste from 500,000 residents directly into the Schuylkill River at about Callowhill Street level. The sewage was thereby put into the river below the drinking water intakes further up river, but still damaged the health of the river. Three water pollution control plants (i.e. sewage treatment plants) were built starting with the Northeast treatment plant in 1928. The depression and World War II delayed construction of the Southeast and Southwest treatment plants until the 1950s. Our neighborhood’s waste flows to the Southwest Water Pollution Control Plant before being released into the Delaware River south of the city. The interceptor pipe mentioned was extended to the Southwest treatment plant in 1956.

Commercial users also fouled the waters. Textile mills, dye plants, chemical manufacturers, and slaughterhouses lined the Schuylkill and Delaware Rivers and added to the human waste pouring into the waters.


Before the common use of refrigeration, livestock was brought alive as close as possible to the cities and slaughtered there. This abattoir, or slaughterhouse, occupied 21 acres on what is now the 30th Street Train Station site from 1877 to 1925. It had pens for 7,300 cattle, 10,000 sheep, and 10,000 pigs. Despite attempts to capture the waste, much of the animal waste and leftovers flowed into the Schuylkill River, albeit downstream of the drinking water supply intakes. Photo credits here and here.


Rain water flows by gravity vertically into the groundwater and horizontally into rivers. This map shows that the Baldwin Park neighborhood is in the Schuylkill River watershed (green) and the rains just to the east of the neighborhood flow into the Delaware River (blue). This makes sense if you go to our article on the Callowhill Cut here. Robert Morris’ proposed canal was to run from a point above Fair Mount on the Schuylkill River to intercept Pegg’s Run, a navigable creek that started at about Broad Street and flowed into the Delaware River.


Chart in the Fairmount Water Works Interpretive Center. The Center, adjacent to the Philadelphia Museum of Art, is a free exhibit that will teach you about both our drinking water supply and our sewer system.


Household flushes in the Baldwin Park neighborhood are treated in the Southwest Water Pollution Control Plant, following the route depicted in the Fairmount Water Works poster above.

But...It’s Not All Treated

It would be nice to think that every flush from your home is sent to a sewage treatment plant before it hits the rivers. The Philadelphia Water Department states that the water discharged into the rivers from the sewage treatment plants is cleaner than the water that was drawn out of the river to begin with. However, in 60% of Philadelphia, the sewer pipes from your home and the storm water sewer pipes beneath the grates on the streets are one and the same. This is true in the Baldwin Park neighborhood. This combined flow of household waste and rain water is ideally sent to the sewage treatment plants before being released into the Delaware River. After a significant rainfall, however, the system can be overwhelmed with the amount of flow and will bypass the treatment plants, flowing instead untreated directly into the nearest river or stream. This is called a combined service outflow and the outlets into the rivers are called outflow points. The three Philadelphia treatment plants have a maximum capacity of 1 billion gallons a day, A 1-inch rainfall will drop roughly 2.3 billion gallons of water on the entire city. Whatever is not retained in soil or human-built structures, or flows into the separate storm water system available in 40% of the city, flows into the combined sewer pipes.


Fifteen billion gallons per year of combined raw sewage and untreated storm water runoff flow into our rivers each year from combined sewage outflows (compared to the 500 million gallons treated each day in the three waste water treatment plants). The outflow from our neighborhood flows into the Schuylkill River at three points visible from the Schuylkill Trail just below the Art Museum. For example, outflow S05, pictured below, overflows on average every five days. This is the outflow with the highest number of outflow incidents per year in the Schuylkill River watershed. The volume of overflow from S05 averages 287 million gallons per year. The other outflow from our neighborhood, S06, averages 67 outflow incidents per year and 121 million gallons. The river water after an outflow incident can be unsafe for recreational use for up to 72 hours after each incident. From July 2021 through June 2022 there were 162 days in which outflow S05 led to unsafe recreational use of the Schuylkill River in its vicinity.


You can explore a map showing all 164 outflow locations in Philadelphia here


View, looking east, of the outlet for the Callowhill Street sewer pipe into the Schuylkill River, outflow S05 (the letter S stands for Schuylkill). The concrete platform on which it sits is the fishing pier just below the skateboard park on the Schuylkill River Trail. Lean over the railings and you can see the outflow marker signs.

Outlet S06 is in the rocky abutment just to the right of S05 about 100 feet downriver. Lean over carefully and you can see the S06 marker.

Outlet S07 is just upriver from this image and has fewer incidents and less volume of outflow per year.

How You Can Help

What can an individual do to lessen the incidence and volume of outflows?

1. Use less water (especially during a rainstorm)!


2. Store rain water. As seen on the map at this link, several residents in the neighborhood have hooked up their home’s rain gutters to rain barrels. The rain barrels are free and professionally installed at no cost to the home resident (see outside link here.  The water in the 55-gallon rain barrel can later be used to water garden plants or wash the car or patio furniture. In addition, this map shows neighborhood sites with the following mitigation measures: retention basins (the Barnes), green rooftops (the Granary Apartments), and rain gardens/trenches (the Alexander Apartments). The goal with all of these measures is to use the neighborhood surfaces as a sponge during rainstorms and release the water more slowly after the rainfall. This should decrease the incidence and volumes of outflows.


3. Avoid building impervious surfaces. Most residential units in our neighborhood are either apartments or condominiums. Most residents are not getting an individual water, sewer, or stormwater bill. The water and sewer bill, as discussed in our article on the water supply in the neighborhood, is based on usage as measured by water consumption. The separate stormwater bill, listed on the monthly water bill, is based on the total square footage of your property (billed at $7.80 per 1,000 square feet) and the charge for the total impervious surface ($11.38 per 1,000 square feet). Even though 500 North 18th Street, the older NxNW tower property, has almost the same land area as the empty lot at 18th and Callowhill Streets, the former pays a monthly stormwater fee that is five times higher than the latter. The impervious surface at 18th and Callowhill is 10% of the total surface, whereas at NxNW the impervious surface is almost 90% of the land area. The less impervious surface there is in a delineated parcel, the more rain is sponged up by the soil and the less immediate runoff into the storm drains. About 54% of Philadelphia is considered impervious: surfaces like street paving, paved parking lots, sidewalks, and rooftops. Even green Matthias Baldwin Park has one-fifth of its surface classified as impervious due to the pathways.

You can find out what portion of your property is impervious to water here.


Rain gardens at the Alexander Apartments in the courtyard at 1601 Vine Street. Notice also the masonry pavers that allow infiltration of water. According to City records, the Alexander Apartments and the Meeting House combined have only about 2,000 square feet of impervious surface, about 2% of the total area, thus dramatically decreasing the stormwater bill.

4. Keep trash out of the storm drains. Trash in the sewers may block the flow within the sewer system and also creates more work to remove the trash at the sewage treatment plants.


Sewer at 18th and Callowhill. Picking up trash, and of course not littering to begin with, will help keep the sewers functioning.


The Friends of Matthias Baldwin Park periodically pick up street trash to prevent river pollution or extra work for the sewage treatment plants. Friends also placed round stickers next to the sewer openings, reminding folks that the trash placed in the sewer may end up in the Schuylkill River.

5. Another way to slow the runoff after rainstorms is to plant more trees. All those empty tree pits on the sidewalks in the neighborhood are great homes for trees, and you can fill them for free by going to the outside link here. Trees take in water from the soil and breathe it out from their leaves, as discussed in our article here. As an example, Baldwin Park had a problem with persistent pooling of water in the north section of the park next to the townhomes. This acted as a mosquito breeding area. The Friends of Matthias Baldwin Park planted a bald cypress sapling in 2022. This species loves moist soil and takes up the water through its root system, eliminating the pooling. In addition, like all trees, it sequesters carbon dioxide into its biomass and pumps oxygen into the atmosphere.

bald cypress in park may 2024 S.jpg

The bald cypress tree, now about twelve feet tall, in the northern section of Matthias Baldwin Park. It was planted as a five-foot-tall sapling in 2022. It tolerates and even thrives in wet soil.

Tree Tenders will describe the growth pattern of a transplanted tree in its first three years as "sleeps, creeps, and leaps." This tree has grown vigorously from its first year. skipping the sleeps and creeps phases.

6. Finally, one last tip for improving our water quality is mentioned on the Philadelphia Water Department website: pick up your dog’s poop! The website claims that the ecosystem can adequately handle the solid waste from 2 dogs per square mile, as far as runoff pollution of the rivers. Let’s do some math. Per surveys, 30% of the households in the Philadelphia metropolitan area have at least one dog. There are just over 4,100 residential units in the Baldwin Park neighborhood (defined as 16th to 21st Streets and Spring Garden to Vine Streets, both sides of all these streets). If our neighborhood is representative of the metropolitan area, that would leave 1,300 dogs in the neighborhood. The neighborhood delineated is one-fifth of a square mile, yielding a doggie-density of 6,500 per square mile. That’s a lot of poop in one small area! Remember to bag your dog’s waste and throw it in your trash.

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