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Tap water is good and guaranteed: quality data

TESTATA Quality Data

Tap water is good and guaranteed: quality data

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In this report:

Quality Data

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 based on international water reports published by other multi-utilities. 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); therefore, data provided cannot take into account any changes to qualitative parameters caused by the piping characteristics in customers' homes.

Analytical results of checks performed by Hera

Values have been calculated as weighted averages (on distributed volumes) of the analysis outcomes performed by Hera. These analyses have been made at network points deemed suitable for providing a concise, reliable picture of distributed water quality. These points have been chosen as they are representative – in terms of position, network interconnections, and in-pipe flow – of the characteristics of the water in the entire distribution system. As for the parameters shown in the following table, Hera has performed 52,511 analyses at representative network points in 2020.

Water quality: average concentrations measured by Hera (2020)

	D.LGS. N. 31/2001	BOLOGNA AREA	FERRARA AREA	FORLÌ-CESENA AREA	MODENA AREA	PADOVA AREA	PESARO-URBINO AREA	RAVENNA AREA	RIMINI AREA	TRIESTE AREA
Alkalinity of bicarbonates (mg/l)	-	253	198	209	235	270	288	192	223	172
Total alkalinity (mg/l)	-	208	163	172	193	-	237	157	183	172
Ammonium (mg/l)	0.50	0.02	< 0.02 ³	< 0.02 ³	< 0.02 ³	< 0.05 ³	< 0.10	0.03	0.03	< 0.05 ³
Arsenic (µg/l)	10	< 1 ³	1	< 1 ³	< 1 ³	1.6	< 1³	< 1 ³	< 1 ³	< 1 ³
Cadmium (µg/l)²	5	< 0.5 ⁴	< 0.5 ⁴	< 0.5 ⁴	< 0.5 ⁴	< 0.1 ⁴	< 1⁴	< 0.5 ⁴	< 0.5 ⁴	< 0.5 ⁴
Calcium (mg/l)	-	83	61	62	109	64	87	59	70	54
Chlorite (µg/l)²	700	176	317	332	80	100	151	344	334	< 100 ³
Residual chlorine (mg/l)	-	0.2	0.2	0.1	0.1	0.1	0.1	0.1	0.1	0.1
Chloride (mg/l)	250	32	32	17	89	8	30	33	21	14
Hydrogen ion concentration (pH)	6.5 – 9.5	7.4	7.5	7.6	7.4	7.6	7.8	7.7	7.5	7.8
Conductivity (µScm ^-1)	2,500	628	518	480	908	446	559	528	531	371
Total hardness (F°)	50 ¹	28	21	21	34	24	28	20	24	19
Fluoride (mg/l)²	1.50	< 0.10 ³	< 0.10 ³	< 0.10 ³	< 0.10 ³	0.06	0.20	< 0.10 ³	< 0.10 ³	< 0.10 ³
Magnesium (mg/l)	-	16	13	14	15	20	15	14	15	12
Manganese (µg/l)	50	< 5 ³	<5 ³	< 5 ³	< 5 ³	< 5 ³	< 1 ³	< 5 ³	< 5 ³	< 5 ³
Nitrate (mg/l)²	50	6	6	5	16	14	5	4	5	7
Nitrite (mg/l)²	0.50	< 0.02 ³	< 0.02 ³	< 0.02 ³	< 0.02 ³	< 0.02 ³	< 0.05 ³	< 0.02 ³	< 0.02 ³	< 0.02 ³
Lead (µg/l)²	10	< 1 ⁴	< 1 ⁴	< 1 ⁴	< 1 ⁴	< 1 ⁴	< 1 ⁴	< 1 ⁴	< 1 ⁴	< 1 ⁴
Potassium (mg/l)	-	2	3	2	2	1	2	4	2	< 1 ³
Dry residue at 180° (mg/l)	1,500 ¹	401	349	329	535	303	396	360	370	236
Sodium (mg/l)	200	23	21	13	56	4	24	24	27	8
Sulphate (mg/l)	250	59	39	36	126	20	63	39	45	10
Total Trihalomethanes (µg/l)²	30	3	1	7	1	4	7	6	6	3

¹ As for total hardness and dry residue at 180 °C parameters, Italian Legislative Decree 31/2001 states a recommended value.
² Parameters 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. Chlorite limit in the mains network water has been redefined by Italian Legislative Decree of 5 September 2006.
³ Absent or lower than instrument measurability threshold.
⁴ Absent or lower than the instrument measurability threshold in the analyses carried out on drinking water treatment plant outflows and therefore not repeated in the distribution network. ⁵ Recommended value: 0,2 mg/l (when used)

As can be observed, all values are well within regulatory limits. Classifying the mains water based on the model applied to mineral water, it can be stated 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, to a lesser extent, nitrate in the Modena area are due to the salinity of the aquifer water. In the Trieste area, hardness values are typical of those of 'soft' waters.

Higher values of calcium (an important component of a balanced diet) are found in the water distributed in Modena, Pesaro-Urbino, and Bologna areas. The water distributed in Padua area shows high values of magnesium (substance useful for the body as it is responsible for many essential metabolic processes), while the water distributed in Ravenna area has high values of potassium (essential substance for the health of the cells).

Higher average chlorate values in Ferrara, Forlì-Cesena, Ravenna, and Rimini areas are essentially derived by the use of higher quantities of chlorine dioxide used to ensure disinfection coverage along very long distribution networks that hold the water in the pipes for a long time.

At local level, certain parameters of historical relevance deemed important for the characteristics of the water at source and/or the treatment methods are monitored as well. For example, checks on tetrachloroethylene + trichloroethylene (organohalogenated solvents) performed in the province of Bologna derive from their presence in groundwater due to past environmental pollution in constant decline and being exceeded in the last three years, mainly due to anthropogenic activities (these compounds are not naturally present in nature). The same goes for the pesticides found in the waters of the River Po which feed into the Pontelagoscuro water treatment 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 (2020)

	Parameter	Italian Legislative Decree 31/2001	Hera Group	Analysis performed by Arpae for Local Health Authority (Ausl)
Bologna Area	Alluminium (µg/L)	200	48	44
	Iron (µg/L)	200	<10	11
	Tetrachloroethylene + Trichloroethylene (µg/L)	10	0.6	0.2
Ferrara Area	Total pesticides (µg/L)	0.50	<0.02	<0.50
Ferrara Area	Pesticides (µg/L)	0.10	<0.02	<0.02
Forlì-Cesena Area	Alluminium (µg/L)	200	49	35
Pesaro Urbino Area	Alluminium (µg/L)	200	47	42
	Iron (µg/L)	200	10	14
	Tetrachloroethylene + Trichloroethylene (µg/L)	10	<1	<0.2

Analysis carried out by the Group indicate that values are well within regulatory limits, 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 in Bologna and Ferrara treatment plants.

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

Across the various areas, average concentrations of parameters have been below regulatory limits by between 78% and 91%.

All the parameters analyzed present average values well below the legal limits. The average values of ammonium, arsenic, fluoride, manganese and nitrite are below the legal limits by over 90%, while those of chloride, nitrate, sodium, sulfates and trihalomethanes-total are below the legal limit by over 80%; total conductivity and chlorite, which present the highest average values - excluding the two parameters of hardness and dry residue for which the legal limits are only recommended, - reach an average of 78% and 71% lower than the legal limits respectively.

Asbestos monitoring performed by Hera

The use of asbestos - extensively employed in construction and other industries until the end of the 1980s - was banned in 1992. It is officially acknowledged that inhaling asbestos fibres results in serious respiratory illness. However, there is no hard evidence that ingesting such fibres is harmful. In May 2015, the Istituto Superiore di Sanità (Italy’s National Higher Institute of Health) confirmed that asbestos fibres in water do not pose a public health risk. As such, at present there is no need to set a parameter value for asbestos in water intended for human consumption any different than the one set by the US Environmental Protection Agency (EPA).
In fact, the EPA study takes into consideration the possibility that asbestos in water might contribute to an increase in the background level of airborne fibres and therefore to increase the risk of inhalation. EPA’s recommendation is that a litre of water should contain no more than 7 million fibres longer than 10 µm (source: EPA, Environmental Protection Agency, Technical factsheet on asbestos). International studies on populations exposed via drinking water have provided insufficient evidence to link gastrointestinal tumours with drinking water consumption (source: Monograph Iarc, vol. 100 C of 2012).
However, this topic remains a source of considerable worry. Hera has responded by running constant checks on the condition of its piping infrastructure and by applying a control plan that focuses on the detection of asbestos fibres in water. Since 2003, Hera has drawn up and applied an annual asbestos control plan. This provides detailed information on the most representative network sampling points, sampling frequency and the relative analytical parameters.
In addition to searching for asbestos fibres that are 10 µm (ten-thousandths of a millimetre) long or longer, analytical parameters are also assessed to determine the aggressiveness of the water i.e. pH, alkalinity, calcium, chlorides, and sulphates. This approach has been adopted because the release of fibres from the cement mass in asbestos cement piping depends on the subtraction of calcium ions and the high aggressiveness of the water.
In 2020, 263 samples have been taken to assess the risk of asbestos fiber release by asbestos-cement piping - 234 in Hera’s territories in Emilia-Romagna region and 29 in Padova and Trieste territories managed by AcegasApsAmga. Test results showed an absence of fibres longer than 10 µm in 95% of the samples. In the 14 samples where fibres longer than 10 µm were found, the number of fibres/litres was between 1,000 and 39,000 - 179 times lower than the limit indicated by the United States’ EPA.
On 323 samples, the “aggressiveness” parameter has been also assessed. Values for this parameter (in 200 cases ≥12, in 123 cases <12) confirmed that the water distributed by Hera generally tends to encrust the cement structure rather than to act aggressively on it (average aggressiveness rating 12.1). It does not, therefore, contribute to the release of asbestos fibres.