Most of us take our drainage for granted; often we assume any issue that arises would be the responsibility of the water supplier. However though, in most cases, you're usually in charge of drains inside the boundaries of one's property, as the sewerage company is responsible for lateral drains, which are beyond property boundaries, and sewers. Although most sewers are actually publicly owned, there are still some private or unadopted sewers. If your property is served by one of these, you may be responsible for maintaining it.
So when there is an issue with the drain inside your property boundaries then it is your responsibility, and they, unfortunately, do block up for various reasons.
Some signs that can help identify a draining issue include:
1. If your toilet, shower, bath or sinks are all draining slowly that is likely an issue with the drain itself. Independent drainage issues will be a concern with the fixture itself. The toilet is often the main driver for a blockage - if flushing the bathroom . causes water to rise in the shower, or running taps causes the water in the toilet to rise, then you've got a blocked drain on your own hands.
2. Foul smells certainly are a dead giveaway for a blockage, if something has blocked the drain and begun to rot, you'll certainly know about it.
3. Finally gurgling noises from pipes, drains and plug holes are all warning signs of a potential blockage. That is created when the air is trapped in the pipes and waste water displacing it.
Usually the 2 biggest factors behind drain issues will be grease/fat build-up and tree root ingress. https://www.tcmdraincare.co.uk/ build-up is a large cause for blockage in the national sewer system and it'll affect homes too. When you wash your plates or just pour fat down the sink, the warm liquidated fat will hit the cold outside water in the drains then solidify, over a period this will build-up causing a blockage.
Root ingress is harder in order to avoid, and most likely the biggest cause for blockages in homes. Root issues can be extremely serious and a large reason behind subsidence related problems. Older clay pipes are particularly prone to root ingress because they are joined with just sand & cement these joints offer little resistance to fine tree roots which once inside become tap roots and root masses which then decrease the internal bore of the pipe.