# Definition of Legal Compliance 

Compliance with the main requirements of the Directive is assessed per agglomeration. Full compliance requires meeting three conditions:

1. **Collection of wastewater via sewers or Individual and Appropriate Systems (IAS)** – necessary for compliance with Article 3, and also a prerequisite for compliance with Articles 4 and 5 (hierarchical approach).  
2. **Secondary treatment of collected wastewater**, i.e., adequate treatment level and performance, is required for compliance with Article 4.  
3. **More stringent treatment than secondary treatment**, i.e., higher treatment level and performance – generally required for compliance with Article 5, i.e. required for agglomerations >10,000 p.e. discharging into sensitive areas or their catchment, or collectively for the group of all agglomerations >2,000 p.e. discharging into a sensitive area of type art5(4) where nutrient removal performance (N and P) must reach at least 75% of the total load of all treatment plants.  


## Hierarchical Approach to Compliance

The legal compliance assessment follows a hierarchical approach:

- **Non-compliance with collection obligations (Article 3)** automatically implies non-compliance with treatment obligations (Articles 4 and, when applicable, 5).  
- **An agglomeration that fails to meet secondary treatment standards** cannot be considered compliant with Article 5.  


## Partial Compliance

Agglomerations may be partially compliant:

- For example, an agglomeration may adequately collect wastewater (compliant with Article 3) but treat it inadequately (non-compliant with Article 4 or Articles 4 and 5).  
- Agglomerations failing to collect wastewater properly (non-compliant with Article 3) cannot be considered compliant with any other Directive requirements.  


## Compliance Calculation

- For non-compliant agglomerations, the portion of wastewater that meets compliance is **not included** in overall compliance rate calculations (regional, national, or EU levels).  


## Tolerances

The total wastewater load of an agglomeration is considered compliant even if[^tolerance]:

- ≤2% (and ≤2,000 p.e.) of the wastewater load does not comply with Article 3, and
- ≤1% (and ≤2,000 p.e.) of the collected wastewater load does not comply with Article 4 
and/or Article 5.
 


## Calculation of Compliance Rates

- Full compliance rate at the Member State level is based on the wastewater load of all agglomerations in full compliance.  

- Article 3 compliance rate (collection) is calculated from the load of agglomerations fully compliant with collection obligations, relative to the total load of reported agglomerations (≥2,000 p.e.).  

- Article 4 compliance rate (secondary treatment) is calculated from the load of agglomerations fully compliant with secondary treatment obligations, relative to the total load of reported agglomerations with obligations under Article 4. This includes agglomerations discharging into sensitive or non-sensitive areas:  
  - ≥2,000 p.e. discharging into freshwater or estuaries, or  
  - ≥10,000 p.e. discharging into coastal waters.  

- Article 5 compliance rate (more stringent treatment) is calculated from the load of agglomerations fully compliant with nitrogen and/or phosphorus removal obligations, relative to the total load of agglomerations subject to Article 5 (≥10,000 p.e. discharging into sensitive areas).  


## Specific case of Article 5(4)

In principle an area subject to Article 5(4) should only be considered compliant if all collection and secondary treatment situated in that area is compliant with the relevant requirements and if the reductions of N and P are at least 75%.

In this case, the compliance should be assessed:

- At the level of agglomerations for Article 3 and Article 4, and  
- At the level of areas subject to Article 5(4) for Article 5.  


## Full Compliance with the Directive

Full compliance with the Directive is calculated on the basis of the wastewater load of the agglomerations in full compliance (Article 3 and, where applicable, Articles 4 and 5) in reference to the total load of all the reported agglomerations.


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[^tolerance]: For more information regarding the tolerance, please check: [https://circabc.europa.eu/ui/group/65764c73-4a57-45dc-8199-473014cf65bf/library/ea692049-6cc8-464d-a0a5-663bc11b98d6/details](https://circabc.europa.eu/ui/group/65764c73-4a57-45dc-8199-473014cf65bf/library/ea692049-6cc8-464d-a0a5-663bc11b98d6/details)