00:00How do we know if the water is clean enough to swim in the Seine River in Paris?
00:11To answer this question, we need to understand what type of wastewater system Paris uses.
00:17It receives not only wastewater from houses and offices, but also takes a large part of
00:22the stormwater generated in the city after rainfall.
00:27The collectors send this mixed water to wastewater treatment plants.
00:33However sometimes the rainfall is so intense that the network doesn't have the capacity
00:38to treat the water fast enough.
00:40To avoid untreated wastewater overflowing into the streets, there are stormwater spillways,
00:46which act as safety valves.
00:47If the capacity of the network is exceeded, the spillways direct the untreated water into
00:52the Seine, and with it different types of bacteria such as Escherichia coli and Enterococci
00:58contained in the wastewater.
01:01In too large a quantity, these bacteria make the water unfit for swimming.
01:06Wastewater reservoirs, like the one at Austerlitz in Paris, have been constructed to increase
01:11the network's wastewater storage capacity and limit overflows into the Seine.
Comments