In such instances, for small developments, a mini waste water treatment plant may be required with discharge to a local water course. This must be agreed with the Environment Agency and the relevant permissions or permits granted.
In circumstances where it might be possible to connect a new development to the mains sewer it is absolutely essential that this is discussed with Southern Water before making a planning application. This is because some treatment plants operated by Southern Water are operating at capacity and Southern Water may reject such an application. It cannot be assumed that a new housing development will be allowed to connect to the main sewer and a private treatment plant for such a development might need to be considered.