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Analytical results of Hera's checks

Given its quality, water supplied by Hera may be classified as 'low mineralised' water with a low sodium content. Local health authority checks confirm the excellent quality of the tap water supplied by Hera.

Tap water quality is described via a table that shows relative values for some parameters. The considered parameters allow mains water to be characterised from a qualitative standpoint. Where necessary, they also allow comparison with the main characteristics of mineral water brands. Parameters are selected also on the basis of international water reports published by other multiutilities. Data is presented in a way that compares it with the limits established by relevant standards.

Concerning water distribution, note that Hera is responsible up to the meter (as per art. 5 of Italian Legislative Decree 31/2001); the data provided cannot, therefore, take into account any changes to qualitative parameters caused by the characteristics of the piping in customers' homes.

Analytical results of Hera's checks

Values were calculated as weighted averages (on distributed volumes) of outcomes of Hera-performed analyses. These analyses were made at network points deemed suitable for providing a concise, reliable picture of distributed water quality. These points were chosen as they were representative - in terms of position, network interconnections and in-pipe flow - of the characteristics of the water in the entire distribution system. With regard to the parameters shown in the following table, Hera performed 49,457 analyses in 2017 at representative network points.

Water quality: average concentrations measured by Hera (2017)
 Italian Legislative Decree 31/2001Prov. BolognaProv. FerraraProv. Forlì-CesenaProv. ModenaProv. PaduaProv. Pesaro-UrbinoProv. RavennaProv. RiminiProv. Trieste
Alkalinity of bicarbonates (mg/L)-307227272254296289227282169
Total alkalinity(mg/L)-252187223209--187231169
Ammonium (mg/L)0.50< 0.023< 0.0230.020.02< 0.053< 0.0530.020.02< 0.053
Arsenic (µg/L)10< 131< 13< 131< 33< 131< 13
Cadmium (mg/L)25< 0.54< 0.54< 0.54< 0.54< 0.14< 0.54< 0.54< 0.54< 0.54
Calcium (mg/L)-9869761186590638356
Chlorite (µg/L)2700168313307< 100145158340276<100
Residual Chlorine (mg/L)-
Chloride (mg/L)250343025911034373714
Hydrogen ion concentration (pH)6.5-
Condutcivity (µScm ^-1)2,500597471502793451605486579346
Total hardness (°F)501332326362529222819
Fluoride (mg/L)21.50<0.103<0.103<0.103<0.1030.10.2<0.1030.1<0.103
Magnesium (mg/L)-191418172217161912
Manganese (µg/L)505< 5< 5< 52< 3< 53< 5
Nitrate (mg/L)250868171565117
Nitrite (mg/L)20.50< 0.023< 0.023< 0.023< 0.023< 0.023< 0.043< 0.0230.01< 0.023
Lead (µg/L)210< 14< 14< 14< 14< 14< 34< 14< 14< 14
Potassium (mg/L)-23221243< 1
Dry residue at 180° (mg/L)1,5001411320351544306434332389240
Sodium (mg/L)2002621196282729308
Sulphate (mg/L)2506440411222278445612
Total Trihalomethanes (µg/L)230205117543

1 For total hardness and dry residue at 180°, Italian Legislative Decree 31/2001 states a recommended value.
2Parameters shown in part B of Annex 1 of Italian Legislative Decree 31/2001. The others are shown in part C of Annex 1 and classified by the "indicator parameters" regulation. For chlorite the mains water limit was redefined by Italian Legislative Decree of 5 September 2006.
3 Absent or lower than instrument detection threshold.
4 Absent or lower the instrument detection threshold in the analyses carried out at the exit of the treatment plants and therefore not repeated in the distribution network.

Analysis results are well within legal limits and comparable with those of mineral water

As can be observed, all values are well within regulatory limits. If we classify the mains water on the basis of the model applied to mineral water, we can state that it is low in mineral content and low in sodium content, except for the water distributed in Modena, which can be defined as mineral water.

Higher average values for chloride, sodium and nitrate in the Modena area stem from the saline nature of the aquifer water. Higher chlorate values in the Ravenna area are essentially caused by the use of higher quantities of chlorine dioxide in Acquedotto della Romagna water (managed by Romagna Acque - Società delle Fonti). This is done to ensure disinfection coverage along the entirety of very long distribution networks that hold the water for a long time. In the Trieste area, hardness values are typical of those of 'soft' waters.

At local level, certain parameters of historical relevance deemed important for the characteristics of the water at source and/or the treatment methods, are also monitored. For example, checks on tetrachoroethylene+trichloroethylene (organohalogenated solvents) are performed in the province of Bologna because they are present in aquifers due to past man-made environmental pollution (these compounds do not occur naturally). The same goes for the pesticides found in the waters of the River Po which feed into the Pontelagoscuro plant in Ferrara. In some cases aluminium is monitored as the salts from this metal are used as flocculants in purification processes.

Water quality: average concentrations of critical parameters at local level (2017) 
 ParameterItalian Legislative Decree 31/2001Hera GroupAnalysis performed by Arpae for Health Authority
Prov. BolognaAlluminium (µg/L)2003830
Iron (µg/L)200<1013
Tetrachoroethylene + Trichloroethylene (µg/L)100.80.3
Prov. FerraraTotal pesticides (µg/L)0.50<0.02<0.50
Pesticides (µg/L)0.10<0.02<0.50
Prov. Forlì-CesenaAlluminium (µg/L)2003030
Prov. Pesaro UrbinoAlluminium (µg/L)2005954
 Iron (µg/L)2001119
 Tetrachoroethylene + Trichloroethylene (µg/L)10<0.80.1


Checks carried out by the Group indicate that values are well within regulations, thus confirming the soundness of the treatment processes. Organic pollutants, especially halogenated solvents and pesticides, are treated via filtration on active carbon which is particularly effective in removing them. The process was implemented inside the Bologna and Ferrara treatment plants.

The following chart compares the quality of the drinking water supplied by the Hera Group with regulations. It shows the calculated ratio between the concentrations of fourteen parameters (ammonium, arsenic, chlorite, chloride, conductivity, total hardness, fluoride, manganese, nitrate, nitrite, dry residue, sodium, sulphate, trihalomethanes-total) measured at points representative of the entire distribution system and their maximum admissible concentrations in drinking water.


Across the various areas average concentrations are below regulations, between 77% - 91%.