In some cities, the costs of discharging sewage into rivers are even several times higher than before.
A storm overflow is a device that drains excess rainwater into a river. However, when they are part of a combined sewer system, sewage and stormwater are discharged through the same pipes to the treatment plant. When it reaches its maximum capacity – which can occur, for example, during intense storms – everything is discharged into the river. This is a problem in many large and old cities where sewage systems were built, firstly, to transport sewage to the rivers and, secondly, in conditions where the flow of rainwater into the sewer system was not so large or so frequent. Today, however, these cities face problems with the accelerated runoff of stormwater, which is influenced, among other things, by the progressive hardening of surfaces and climate change.
The problem is that the fees that water and sewage companies have to pay are tied to storm overflows by the Special Odra Law. Starting from the beginning of the year, if such a device is released at least once in a given quarter, the company will incur a 10% variable fee for the discharge of treated sewage from the treatment plant that serves the sewage network where a particular storm overflow is located. And there can be up to several dozen of them in the city. − If they did not exist, excessive rainfall would cause a mixture of sewage and storm water to be discharged into inhabited areas, notes the spokeswoman for the Krakow City Water Service.
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