There are many causes of blocked drains – below are just some of the examples:
What causes a drain to block?
Nature
Tree roots may be the cause of blocked drains, as they search for the closest source of water and can crack pipes, leading to blockages.
Too many leaves clumped together when wet can cause drains to become blocked.
Domestic
Grease and fat are well known for sticking to the sides of pipes and gradually building up over time, until eventually no more liquid can pass through. At this point, the problem will become evident and action will be required.
Foreign objects
Nappies, clothes, sanitary items and an excess of tissue paper are sometimes flushed down a toilet, which can eventually cause a blockage in the drain. Young children, in particular, often delight in flushing anything and everything down the toilet!