Source protection zones for site checks in England and Wales
Source protection zones identify risks to groundwater drinking-water sources. Check England and Wales maps, zone meanings and the limits of site screening.
Source protection zones in England and Wales
Source protection zones (SPZs) identify areas where activities could contaminate groundwater used for drinking water. SPZ1 is the inner zone, SPZ2 the outer zone and SPZ3 the total catchment. Their boundaries depend on groundwater travel time and the area feeding the source. The Environment Agency's SPZ guidance explains these boundaries for England.
For a site check, use the official mapping route for England or Wales. But a blank map isn't clearance. Some private supplies are not shown, and a mapped zone is not a blanket ban on development. The EA's groundwater protection guidance explains those limits.
What the groundwater source protection zones mean
A groundwater source protection zone follows the area feeding the abstraction, not a standard circle around a borehole. For SPZ1 and SPZ2, compare the travel-time area with the minimum-radius area. The larger area applies, as set out in the EA's boundary definitions.
| Zone | Meaning | Minimum-radius qualification |
|---|---|---|
| SPZ1: inner zone | Up to 50 days' groundwater travel time to the abstraction point | At least 50 metres; use the larger area |
| SPZ2: outer zone | Up to 400 days' groundwater travel time | At least 250 or 500 metres, depending on authorised abstraction volume; use the larger area |
| SPZ3: total catchment | The catchment within which all groundwater can potentially feed the source | Not a fixed-radius buffer |
The inner and outer zone rules are on the EA SPZ definitions page. The total catchment wording is in the groundwater protection guidance.
For SPZ2, divide the maximum allowable annual abstraction volume by 365. Below 2,000 cubic metres per day, the minimum radius is 250 metres. At or above that threshold, it is 500 metres. Use the authorised volume, not actual daily pumping, when applying this boundary test. These are minimum radii. A larger 400-day travel-time area still applies.
The travel times describe groundwater movement below the water table. They do not give a guaranteed arrival time for a surface spill, as the EA's groundwater guidance explains.
How to check a site in England
Start with MAGIC. The EA's published instructions give this route:
- Open Designations.
- Choose Land-based designations, then Non-statutory.
- Select Source Protection Zones Merged (England).
- Search by postcode, zoom to the site and adjust the transparency.
Follow that published route and read the legend on the day you check. The same guidance page identifies Defra Data Services Platform data as an alternative.
Check the whole site, including proposed discharge, infiltration or drilling locations. Look for subsurface zones marked 1c, 2c or 3c. These address risks beneath protective cover, including pathways that drilling could create. A surface-only check can miss that issue. The SPZ guidance also describes SPZ4, a zone of special interest where local conditions need extra protection.
Keep a dated map extract with your site-screening notes. It is not a statutory checklist. Use it with the desk study and source identification in the groundwater risk-assessment guidance.
How to check a site in Wales
Use Natural Resources Wales' map guidance to reach its current viewer. NRW says users can search by place name, address or grid reference. An England-only MAGIC layer is not the right route for a Welsh site.
NRW's data-access guidance identifies DataMapWales as its published open-data route. Search for source-protection data and read the dataset metadata before using a boundary in your assessment. If you cannot find the relevant layer, or the boundary is unclear, ask NRW to confirm it.
Why a blank map needs further checks
In England, the EA says all private water supplies used for human consumption or food production have an SPZ1 designation with a default radius of 50 metres. The same guidance says food production purposes do not include routine irrigation of crops. Details of those supplies are not held on the interactive maps. Local authorities regulate these supplies, according to the EA's groundwater protection guidance.
Ask about nearby private sources as well as checking mapped zones. For Welsh private-supply questions, seek confirmation from NRW or the local authority rather than relying on an England-only map or rule description.
Where relevant to the activity, the EA's groundwater risk-assessment guidance calls for a water-features survey that includes private and licensed abstractions. The survey distance depends on the activity. Don't treat it as a fixed source protection zone boundary.
What the result means for your project
A groundwater protection zone on these maps is a screening result, not planning permission or an environmental permit. The EA says SPZs are not statutory, but they relate to distances and zones in legislation where certain activities are restricted. Being outside a zone does not remove activity-specific obligations, and being inside one does not prohibit every activity, as the EA's explanation sets out.
Use the zone result in a groundwater risk assessment. Identify potential pollution sources, routes through the ground and the water supplies that could be affected. The EA's risk-assessment guidance sets out the desk study and conceptual model for those connections.
The Environment Agency does not regulate Welsh sites. Natural Resources Wales has adopted the Environment Agency's approach to groundwater protection, and its staff use that guidance when they decide planning and environmental-permitting applications in Wales. Welsh law and NRW requirements still apply. An England-only amendment does not apply in Wales merely because the EA published it.
The position-statements page, updated on 2 October 2023, calls the document "The Environment Agency's approach to groundwater protection" and marks it under review. It also describes an England-only 2023 amendment.
RegAffairs AI's answer on source protection zones covers the question for England and Wales.