Generally people are totally unaware of the drainage system serving their properties or their associated legal responsibilities. It is recommended that as a householder you investigate and familiarise yourself with your drainage system before you have problems, and understand where your drains go. You should at least be familiar with where the inspection chambers (manholes) are within your garden. It is surprising how many times these have been covered or hidden. If possible, determine this with the previous occupier when you buy a property.
It is also advisable to check them periodically to confirm the drains are running properly.
You should be aware that you are responsible for the cleansing ( of blockages ) and maintenance of the drains serving your property up to the point at which they either combine with someone else's or join the 'adopted' Public Sewer (which normally is under the highway adjacent to your property).