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Boundaries of Waterside Properties

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The exact line of a legal boundary is often left unclear in conveyancing. Trying to describe it exactly without precise measurements and accurate large scale plans can be problematic. For example, a boundary may be marked by a physical boundary, which may be natural (such as a river) or artificial (such as a wall). The actual boundary line may be either side of the feature that marks the boundary or the median line through the boundary feature.

Commercial Property Solicitor Russell Brasington says, “Where a property is bounded by water both the physical and legal boundaries may move over time as sea levels rise, the course of a river changes or material is deposited or taken away. These changes may occur naturally and imperceptibly over long periods of time or may happen suddenly as the result of a particularly strong tide or the weather or human activity.”

So what guidance does the law offer about boundaries of waterfront properties?

Sea-shore, tidal rivers or inlets

Where land adjoins the sea, there is a rebuttable presumption that the boundary of the land extends to the top of the foreshore, which is the land that lies between the high and low water marks of an ordinary tide between spring and neap tides. The boundaries may move gradually as the high water mark moves naturally over time.

The foreshore is owned by the Crown unless it has been demised or granted as it often was after the Norman Conquest. Sembcorp (formerly Bournemouth and West Hampshire Water Company) now owns around three quarters of Christchurch Harbour, together with the tidal reaches of both the Stour and Avon rivers. The same presumption applies to land that borders tidal rivers and inlets.

Non-tidal rivers and streams

There is a rebuttable presumption that where a property abuts a natural non-tidal river or stream, the boundary of the property extends to the centre line of the river. If the course of the river changes naturally over a period of time, the property boundary is presumed to change with it. This will not apply, however, where the course of the river is artificially changed or where it is changed suddenly, no matter how.


There is a rebuttable presumption that where a lake is entirely within the boundaries of a single ownership, the same person will also own the bed of the lake. There is no presumption where the lake is not entirely within the boundaries of a single ownership.


Under the doctrine of accretion, where the effect of natural forces such as currents, tides and winds causes a gradual increase or decrease in the amount of land, the legal boundary of the affected land is adjusted accordingly. This will also apply where the changes are the consequence of human behaviour, provided that it is not the deliberate action of the party claiming ownership.

The doctrine of accretion only applies to changes which are gradual and imperceptible. It does not apply to substantial and recognisable changes. A sudden accretion of substantial size, or the creation of an island, belongs to the Crown.

Where land with a water boundary is transferred or leased, the doctrine of accretion will apply unless it is excluded. This means that a tenant of land affected by accretion will obtain the benefit of the accreted land and the terms of the lease will apply to it. An agreement excluding accretion in relation to registered land must be registered.


We have offices in the Christchurch, New Milton and the New Forest. Our Commercial and Residential property teams also cover Bournemouth and Poole. For a free initial chat, please call 01202 499255 and a member of the team will be happy to discuss any questions that you may have.