Boundaries – dispelling the myths article banner image

Exact boundaries can be hard to define – especially when changes happen over time.

Establishing boundaries is very important because the boundary of a property determines the extent of land and the rights and liabilities of a property owner or occupier.

The million dollar question is therefore, how do you determine the exact location of the boundary?

The first port of call in any boundary dispute should be to inspect the title deeds and plans annexed thereto. However, there is no guarantee that these documents will provide a definitive answer. It is commonplace to find that:

  • the description of the land being transferred lacks sufficient detail
  • the scale of the plan is too large to allow boundaries to be accurately established
  • the boundary marked on the plan, typically in red, when scale is taken into account, provides for a 3m wide boundary on the ground and as a result there is no certainty as to where the exact boundary lies


A physical feature such as a fence, wall or hedge will often follow the line of a legal boundary and can provide a good indication of where a boundary lies. It is important to consider however that it is not unusual for the physical boundary feature to run within the legal boundary structure. For example, where the legal boundary between two fields is a hedge, where there are stock or horses on the land it is not unusual for a fence to be installed a few feet in from the hedge. In such a case the fence does not demarcate the legal boundary.


But what is the position if the boundary changes over time?

In the case of land adjoining a watercourse it is not unusual for the boundary to alter over time. The law accounts for this phenomenon using the doctrine of accretion and diluvion which recognises that where land is bounded by water the forces of nature are likely to cause changes in the boundary.  An increase in land is known as accretion whereas a decrease in land is known as diluvion.

This doctrine applies where the changes to the boundary are either:

1.    Gradual and natural by virtue of time; or

2.    The result of human actions, provided that they are not the consequence of the deliberate actions of the party claiming ownership.


Importantly, where the change in boundary is clearly substantial, for example a water course is permanently moved into a different direction due to a violent flood, then the doctrine does not apply.

Land is conveyed subject to and with the benefit of any additions or subtractions that may have taken place over the years. The fact that the title plan may show the boundary in a particular position does not affect the loss of the land resulting from the operation of the doctrine of accretion. If the properties are separated by a non tidal river or a natural stream, the presumption is that the boundary will follow the centre line of the water (‘ad medium filum aquae’) so that the respective properties on either side of the stream will own half of the bed. If, of course, the stream alters over a period of time the position of the boundary would also change.

The doctrine also applies to the boundary of land adjoining the sea. Here the standard presumption is that in the absence of evidence to the contrary, the boundary lies at the top of the foreshore, whilst the foreshore is owned by the Crown. This assumption also applies to land bordering on tidal rivers and sea inlets. The boundary may move gradually, as the line of the high water mark moves naturally over the years. However, in the case of a sudden substantial accretion of land or conversely an encroachment by the sea, the ownership of the area of land affected will not change.


If you have a question or query for Ed Fowler, solicitor in our Devon rural team please email or call 01392 210700.