Protection zones and protection areas of drinking water sources
Preserving drinking water quality is not only the task of water treatment but begins much earlier, in the environment surrounding the water source. This purpose is served by so-called drinking water source protection zones (surface extent) and protection areas or protection volumes (subsurface spatial extent), which aim to prevent pollutants from entering the groundwater or surface waters used for drinking water supply.
The protection zones and protection areas of drinking water sources are designated areas from which groundwater supplying the source flows toward the abstraction wells. The delineation of these zones is based on hydrogeological investigations, flow modeling, and legal regulations, and it is mandatory for all public drinking water sources.
The System of Protection Zones
In Hungary, protection zones and protection areas are divided into three main zones based on the travel time and risk of contamination.
1. Inner Protection Zone
The immediate surroundings of the water abstraction structure (well, spring). Typically extends only a few tens of meters. Purpose: exclusion of immediate contamination sources.
Restrictions:
Access by unauthorized persons is restricted. All polluting activities are prohibited (storage, construction, agriculture).
2. Outer Protection Zone
The area from which contamination could reach the well within a few years. Its extent may be significant, depending on the type of water source.
Restrictions:
Regulated agricultural activities. Restrictions on the storage of hazardous substances and on industrial activities. Prohibition of wastewater disposal and waste landfilling, or allowance only under strict conditions.
3. Hydrogeological Protection Zone
The entire recharge area of the water source, often extending across the administrative boundaries of several municipalities. Divided into two sub-zones (Zone A and Zone B) depending on whether the area has faster travel times or slower flow over a larger area.
Restrictions:
Limitations defined by land-use and development regulations. Restrictions on permitting environmentally burdensome facilities.
Importance of Protection Zones for Different Types of Water Sources
Bank-filtered water sources: rapid response is critical, as surface water quality has a direct impact on the water source.
Karst water sources: protection zones are particularly extensive because water can reach wells quickly and without natural filtration.
Confined aquifer sources: geological protection is higher, but the risk of long-term contamination (e.g., arsenic, industrial pollutants) still exists.
The protection zones of drinking water sources are among the most important preventive tools for safeguarding drinking water quality. Properly designated and enforced protection zones ensure that water sources remain safe and usable not only today, but for decades to come.