A Report From the Sewers of Paris

There is an art gallery along the walls of the first tunnel you enter, with various portrayals of sewer monsters. Entering another tunnel, there are displays with mannequins dressed in gear to enter the sewers, and equipment they use. Next was the display of taxidermy sewer rats. In my opinion, the Paris sewer rats look different than Portland rats, with their little berets and baguettes. Another tunnel shows off colorful display posters and models about the sewer and drinking water system, watersheds, and fish. In one of the final tunnels was a series of displays of the history of the Paris sewers.

To give some perspective, the history of Portland began in 1843 on the Willamette River in what was then called Oregon Country. In 1851 the City of Portland was incorporated. Portland’s first sewer was a covered wooden trough that ran from SW Montgomery Street to Fourth Avenue, then to the Willamette River, built in 1864. Portland’s Columbia Wastewater Treatment Plant began collecting and treating wastewater in 1952.

Compare this to the ancient history of the Paris sewers. Until the Middle Ages, the drinking water in Paris was taken from the river Seine. The wastewater was poured onto fields or unpaved streets, and filtered back into the Seine. Around 1200, streets were paved, incorporating a drain for wastewater in the middle. The first vaulted, stone-walled sewer was built in 1370. In 1850 the present Parisian sewer and water supply networks were designed and separate water supply networks were built for drinking water and non-drinking water. A 373-mile sewer network followed in 1878. A sewage treatment program (designed to meet needs for the next 50 years), was approved in 1935.

Paris has a combined sewer/sanitary system and aging infrastructure, like Portland. In 1991, a 20-year plan was developed to restore the existing sewers, protect the Seine River from untreated rainwater during storms, improve working conditions, and modernize operations. The quality of the water in the Seine has significantly improved in recent years. There are now over 20 species of fish in the river, compared to only three in the 1970s.

The sewer museum was one of the highlights of my first trip overseas. It was exciting to see a different infrastructure and to learn that Paris poop smells just like Portland poop.

Paris Sewer System Facts:

• 70 measurement stations
• 22 storm overflows equipped with gates
• 6 pumping stations
• 8 flood pumping stations and 45 storm overflows are used as safety valves in the event of network overload
• 6,500 flushing chambers are used to clean the sewers periodically
• 97 grit chambers trap the sand and silt carried by the wastewater
• 9 siphons have been built under the river Seine to channel wastewater from one bank to the other
• 2400 km (1491 miles) of sewers; 40 km (25 miles) of main sewers, 140 km (87 miles) of secondary sewers and 1400 km (870 miles) of primary sewers evacuate wastewater to the treatment plants
• 30,000 manholes have been installed every 50 meters (164 feet) to provide access to the sewers and there are 18,000 drains to channel surface water from the streets into the system
• 100,000 private connections link the buildings to the network
• 1 storage tank with a capacity of 17,000 cubic meters
• Treatment Plant capacity is more than 2 million cubic meters/day (528,344,104 million gallons)
• Population 2,241,346 in the City of Paris.
• French families spend an average €1 ($1.16) a day on water and wastewater services, for approximately 330 liters (0.26 US gallons) of water supplied and sent to the wastewater system every day.
• Paris has an average of 24.4 inches of rainfall per year over an average of 162 days per year

Debbie Caselton has worked in Public Involvement and Community Outreach for Capital Improvement Projects for City of Portland’s Environmental Services for 16 years.