The sewer system is only designed to carry wastewater, human waste and toilet paper. Any other items put into the pipe can get stuck, resulting in blockages and, in the worst cases, sewage backing up into homes, gardens and streets.
Blocked drains are most commonly a result of tree roots, unsuitable products, such as cooking fat, wet wipes and sanitary products, building up in the pipes. Drainage pipes from your home are usually only 10cm in diameter and can easily become blocked if the system is abused.
Stormwater can also play a significant role here. If the drain system is fine, water goes smoothly, but when it gets a huge flow, your drain system may not be able to handle the situation smartly. This will cause water to overflow. The most common causes are tree roots, leaves and dirt which blocks the drain, causing the water to flood.