Before you alter or install a new drainage system it is always necessary to inform the Building Control Department or the local council offices. In fact, it is necessary that the present plans comply with Building Regulations.

There are different types of drainage systems: foul water and surface water. The former regards everything that come from bathrooms, kitchens, car washing areas, utility rooms and similar. The latter regards rainwater only.

The construction of a below ground drainage system can be divided in main phases.  First of all, it is necessary to decide the size and the number of all the components that are required in order to design the drainage system (pipes, bundles). Furthermore, the transport and handling of the selected elements represents a further step. The next phases regards the excavation of the area which positions the system. In this phase it is essential to take precautions against trench collapse and to not open trenches too far in advance of pipe laying. Consequently, the pipes can be accommodate on the ground providing appropriate protection in order to avoid damage due to pressure and ground movement.

Moreover, it is possible to determine the capacity of a drainage system by the diameter and gradient of the pipework. The required capacity of the system also depends on the calculation of flow rates. All the individual sanitary appliances have a Discharge Unit value that allows to establish the flow rate. BS EN 12056-2:2000 specifies the Discharge Unit values as dependent on the soil system configuration to which they are connected.

Syntegra Consulting is a leading energy consulting company in the UK – for further information about how to design and implement below ground drainage systems please telephone +44 (0) 845 0091625 or e-mail: