'Private shared sewer' liability/responsibility explanation

This is a basic plan explaining the liability or responsibility aspect of drainage systems on a 'private shared sewer'. This is purely for example purposes and is not specific to your situation. A private sewer is deemed private until it joins the public sewer.

As you can see, there are four properties, with a manhole located within each of their property boundaries. The drain run then connects to the public sewer, in this example, located in the adjacent highway.

There are two problem areas of drainage on this system and they are marked on the plan as 'X' and 'Y'.

Problem 'X' is located within the property boundary of House C, but only Houses A and B use this section of pipe at the point of damage, therefore the liability falls jointly between house A and B to correct the problem. House C connects to the shared system downstream (i.e. after) the problem area at Manhole C. This is classed as derivement of benefit. Houses A and B are the only properties deriving benefit from the drain at problem 'X' and are therefore jointly liable for the cost of the repair.

Similarly, problem 'Y' is the shared responsibility of all four properties, even though the problem is located in the highway, as it is upstream of (i.e. before) the connection to the public sewer and therefore still classed as part of the private sewer.

This is how insurance companies will expect the repair costs apportioned, and why your property's allocated cost may be higher or lower than that of your neighbours.