Overland surface water ﬂow between private properties usually occurs when the below applies:
The natural contours are sloping
Surface water is being concentrated, diverted or redirected on to other property
Ideally, run-off should be directed towards the street or a drainage system, if provided.
Cut-off drains and perimeter banks are also helpful in directing run-off towards the street or into a private drainage system.
Property owners are required to accept natural water overland ﬂow from adjoining properties or public land.
Surface water ﬂows to the lowest point. An upstream property owner cannot be held liable merely because surface water ﬂows naturally from their land on to the lower land of a neighbour. It is the responsibility of a downstream property owner to manage and protect the lawfully constructed building structures on their property. This could be achieved by installing private drainage to protect a property.
Property owners need to be aware that landscaping can change the topography of a property and the way it distributes water.
To put it more simply, if you are downstream, you must accept the ‘natural’ run-off on to your property. When constructing hardstand areas you must control stormwater in order to prevent it from flowing on to a neighbouring property. It is preferable to minimise the area of water-resistant surfaces such as concrete or paved areas and driveways. If there is an easement on your property it must be maintained and kept clear of debris to allow the natural flow of stormwater to the field gulley.