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Why and How is Bathing Water Quality Assessed?

 

Table of contents

 
 

Interpreting the Results

published on 01/08/2008
 
 

Interpreting the Results

During the bathing season

The results of each analysis are compared to the quality thresholds set for the microbiological criteria in the chart below:
  • Water is of good quality when the results are below the guidance values,
  • Water is of average quality when the results attained exceed the guidance values, but remain lower than the imperative value,
  • Water is of poor quality when the results exceed the imperative value.

Total coliforms UFC/100mL

Guidance value = 500
Imperative value = 10 000
GOOD RESULTS
AVERAGE RESULTS
POOR RESULTS
0  
500
 
10000
 

Escherichia coli UFC/100mL

Guidance value = 100
Imperative value = 2000
GOOD RESULTS
AVERAGE RESULTS
POOR RESULTS
0  
100
 
2000
 

Intestinal enterococci UFC/100mL

Guidance value = 100
GOOD RESULTS
AVERAGE RESULTS
0
100
 
Should the imperative value be exceed, bathing may be prohibited by order of the prefect. An investigation is then carried out to identify the causes of pollution in the bathing area.

At end of bathing season

At the end of the bathing season, each bathing site is classified based on the samples taken during the season. The classification takes into account the following six parameters:
  • 3 microbiological parameters: total coliforms, Escherichia coli and intestinal enterococci.
  • 3 physical/chemical parameters: mineral oils, tensioactive substances (foams) and phenols.
Pursuant to the provisions of Directive 76-160 regarding the quality of bathing water, incorporated into French law through the Public Health Code, the percentage of analysis results in line with the guidance values and imperative values for the 6 parameters, the waters are classified as either compliant or non-compliant. Bathing waters are deemed compliant if all of the results remain below the imperative values.
In France, bathing water is further classified into four quality categories:
  • Waters deemed “compliant" under the European Directive are referred to as being of "good quality", in Category A (compliant with guidance values and imperative values under the European guidance values and imperative values) or as "average quality", in Category B (compliant with imperative values);
  • Water deemed “non-compliant” are temporarily polluted, and fall either into Category C (5 to 33% of samples taken during any bathing season do not comply with the imperative values) and poor quality water, in Category D (over 33% of samples do not comply with imperative values).
Criteria for classifying bathing water in France
A
Good-quality water
B
Average-quality water
 
At least 80% of Escherichia coli results are lower than or equal to the guidance figure
At least 95% of Escherichia coli results are lower than or equal to the imperative value
At least 90% of faecal streptococci results are lower than or equal to the guidance figure
At least 95% of total coliform results are lower than or equal to the imperative value
At least 80% of total coliform results are lower than or equal to the guidance figure
At least 95% of results are lower than or equal to the required thresholds on mineral oils, phenols and foams.
 
At least 95% of samples are compliant with the imperative value on Escherichia coli and total coliforms;
At least 95% of the results are lower than or equal to the required thresholds on mineral oils, phenols and foams.
The conditions regarding guidance figures are not checked, either in full or in part. 
Les eaux classées en catégories A ou B sont conformes à la réglementation européenne
C
Water that may be temporarily polluted
D
Poor-quality water
  Imperative values are exceeded 5 to 33.3% of the time.   The conditions on imperative values are exceeded at least one-third of the time.
In all areas classified in Category D one year, bathing must be prohibited the following year.
Waters classified in Categories C or D are not compliant with European standards.