Land area within property boundaries.

Waters defined and protected under the Water Resources Act 1991. Any relevant territorial waters that extend seaward for 3 miles from the baselines, any coastal waters that extend inland from those baselines to the limit of the highest tide or the freshwater limit of any river or watercourse, any enclosed dock that adjoins coastal waters, inland freshwaters, including rivers, watercourses, and ponds and lakes with discharges and groundwaters (waters contained in underground strata).For the full definition refer to the Water Resources Act 1991.

A covered channel or pipeline (defined by the Highway Agency as wider than 900mm).

The area of the catchment that contributes storm runoff directly to a sewerage system.

Term used in the UK for discharges that meet conditions imposed by the appropriate public authority for potentially polluting flow to a watercourse or into the ground.

An outfall from a combined sewer designed to prevent the capacity of the sewer or a sewage treatment works from being exceeded under storm flow conditions by allowing the discharge of excess diluted sewage to another sewer, tank, watercourse or some other disposal point.

A sewer design to carry surface water and foul sewage within the same pipe.

Foul sewage mixed with surface water, also known as storm sewage.

A sewer network that collects rainfall from impervious surfaces and foul water from domestic and industrial sources.

In wastewater, a system of conduits, generally underground pipes, which receive and convey sanitary wastewater (domestic and/or industrial) and/or stormwater.

An empirical equation relating flow to roughness and gradient of a conduit and the viscosity of the fluid.

The process of implosion of air in water that is a function of high velocities, which cause damage.

The area contributing surface water to a point on a drainage or river system, which may be divided in to sub-catchments.