The installation or alteration of drains does not generally require planning permission but may depend upon the extent and position and guidance should be sought from the Planning Authority.
Biodisc, Septic tanks and soakaways
A new installation requires planning permission.
Planning permission is not required for the installation of a replacement waste water treatment system (any sewerage treatment facility) provided no part of the development is constructed within nine meters (measured at ground level) of the route of any overhead electrical line carrying more than 11Kv or more (High Tension Power Cable), it must be more than 9.1 meters away from the bank of a main river (as designated under the Land Drainage Acts) and its placement (including foundations/ground works) must not involve the felling, lopping or limbing of any tree (other than a tree referred to in Section 3(3) of the Tree Preservation Act 1993) OR interfere with the root system of any such tree.
These conditions are defined in detail Part 2 , Section A (page 15) of the Permitted Development Order.