The Water Hardness dataset has been updated so that each month, new postcodes—flagged by Royal Mail as Not Yet Built—are appended. This ensures that all postcodes are listed, including those not yet officially listed as live.
Each quarter, the dataset is recompiled against the confirmed postcode file to ensure that all new entries are assigned to the correct location. A status flag is also applied to indicate whether a postcode has been terminated.
Key reasons for postcode termination include:
- Operational efficiency: Royal Mail updates postcodes to improve mail routing, for example when new delivery offices are introduced.
- Property changes: When buildings are demolished, redeveloped, or renumbered, the associated postcode may be discontinued.
- Volume changes: Historically, areas with low mail volumes (such as NE and S in London during the 1860s) were terminated to streamline delivery.
- Capacity constraints: When an area runs out of available codes for new addresses, a postcode may be retired and replaced with more granular alternatives.
- Reallocation: In some cases, a postcode is terminated in one location and later reused elsewhere.
These changes are now live.