8 Disadvantages of Combined Sewer System
Some of the households utilise a combined sewer system. This system is a collection of underground sewers that transport industrial and domestic sewage and water runoff into a wastewater treatment plant before releasing and discharging them into a water course after treating them. By the time it was introduced and implemented, it was adored for the amazing contributions and convenience it has offered to many homeowners and residents. After a storm, a snowmelt or a rainy season, they then discovered how it really was. Behind the comfort and the convenience it offers, it has so many disadvantages accompanying it. Combined sewer system has its own limitations and let me tell you the eight primary limitations.
When water runoff and domestic or industrial sewage are mixed due to the overflow incidents, contamination would likely take place. During snowmelt or rainy seasons, water runoff tends to increase its volume and occupy so much space in the sewer system. That volume increase gives way to overflow and contamination and can somehow pose health threats when drinking water has been contaminated as well.
As I have mentioned earlier in the article, combined sewer carry both sewage and water runoff. After treating this wastewater, they are discharged on the nearby water course. When sewage and water runoff combine due to an overflow, sewages might be discharged in the water course as well. It may carry harmful chemical solutions that are the main culprits of water pollution. That is the reason why most environmentalists do not encourage the utilisation of combined sewer system due to its environmental impacts and destruction.
3. Death of marine animals
Upon polluting the water by discharging sewages that may contain chemical solutions, it can cause the death of the marine species present in the said water course. Endangered marine species might be killed as well thus, reducing the number of species in the water. Environmentalists are concerned with the wellbeing of our nature that is why they strictly do not promote this kind of sewer system to be used in many households.
In some other ways, harmful chemicals carried by sewers may reach the water courses. This will be taken by the marine species and can somehow make them poisonous. When this marine species such as fishes, are caught and ingested by the public, they might be hazardous to the people’s health and cause death or serious illnesses.
5. Waterborne diseases
Professionals and scientists have proven that sewages from households and industries contain pathogenic organisms that cause waterborne diseases and various illnesses. This may cause diarrhoea, poisoning and death. These pathogens may be in direct contact with human beings during overflow incidents where the mixture of storm water and sewages comes out of the gully inlets which are supposed to be the water runoff’s entrance towards the sewer system.
6. High upfront cost
The installation of a combined sewer system is said to be higher than that of the other kind of sewer system because of the laborious tasks it involves. Their suggested pipe path usually falls under roads and pavements and the restoration processes of the destroyed properties may add up to the service rate. Special engineers are needed during installation because this sewer system involves complex designs and complicated procedures.
7. Deep excavation
Combined sewer installation becomes laborious due to the heavy excavation processes. This sewer system involves large trenches because of the large volume of water it will convey during storms and snow melts. In this case, labourers would need to excavate in order to perfectly lay the trenches.
Maintenance cost of this sewer system is relatively high. This should always be maintained because this system should retain a specific velocity to prevent solid wastes and debris build-up.