The checks that ensure good clean water
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HERA'S QUALITY CONTROL
Stating that water is good to drink means guaranteeing its quality and healthiness in full compliance with standards. Water control plans are therefore drawn up by both the provider and local health authority departments (USLs).
In managing the water system, Hera ensures that its customers receive water that is good to drink and compliant with regulations. Monitoring is constant and involves planned, targeted controls along the entire drinking water chain, from source to final distribution.
Quality checks on drawn and distributed water involve monitoring and control methods that are applied to all managed mains supplies. More specifically, an Analytical Control Plan is drawn up every year by the Integrated Water Service. The aim of this document is to ensure compliance and high product quality. The Plan documents:
- the sampling points subject to checks along treatment and distribution lines;
- the analytical parameters subject to monitoring;
- the frequency of analysis.
The choice of analytical parameters and relative frequencies is also influenced by the need to keep any problems highlighted/documented in the historical database under control.
Rather than an exhaustive number of readings, the Plan gives more importance to 'significant' high-quality data. In fact, while homogeneous base checks are carried out across all served areas, the Plan is specifically designed to respond to certain plant engineering requirements or specific monitoring needs highlighted by long-term data. Such criteria complies with the most recent guidelines published in Italy, which state:
- for routine water quality monitoring, a high number of checks focusing on justsome parameters sometimes is more meaningful than a few checks that take readings of many parameters. Such parameter readings are often, given the history of the source, unjustified;
- it's preferable to perform more frequent checks on the most significant parameters at the most significant points as opposed to running less frequent checks on a higher number of parameters at all withdrawal points, thus basing monitoring plans on careful assessment of historical analytical databases;
- the plan is based on risk assessment criteria (Water Safety Plans) according to the principles expressed in European Commission’s Directive 2015/1787.
In order to prevent or minimise the risk of non-compliance, the level of water quality monitoring should not be based on simple quantification of the number of readings taken but, rather, through meticulous selection of the parameters to be monitored. The main criteria used to draw up the Plan are as follows:
- observance of EU, national and local standards in force;
- the concept of the mains supply as a “water production plant” for human consumption purposes (i.e. a single production system to be managed and controlled via an integrated approach);
- full awareness of the significance of analytical parameters and their dynamics;
- a preference for parameters of a general nature (e.g. conductivity) able to highlight unusual changes in water quality that can then be investigated through further analysis;
- an understanding of the degree of vulnerability of used water sources;
- examination of past analytical data to verify critical parameters and risk levels;
- an understanding of the distribution network in terms of length and the materials in contact with drinking water (including water towers/tanks and other systems);
- an understanding of the reagents used in water treatment and distribution.
The taking of samples to be analysed is a particularly delicate phase of the quality control process. Where samples are taken for microbiological analysis purposes strict aseptic protocols are observed. This prevents any secondary contamination that is not imputable to the actual characteristics of the water.
Also in the areas served by AcegasApsAmga, monitoring of all processes is defined in special area-specific “Monitoring Plans“(defined together with local health authorities). Taking into account any specific problems concerning individual systems, such plans acknowledge the requirements of the regulations in force by defining the following types of analyses:
- monitoring of sources (wells, springs, surface waters);
- monitoring of purification systems;
- checks, performed directly at distribution system production, pumping and storage points;
- routine checks carried out directly at end user points in the area;
- follow-up assessments needed to investigate any problems that may have emerged from the above checks or from customer complaints;
- controls on backup samples where analysis is effected by third parties;
- research into and control of “unregulated” substances (e.g. checks on emerging pollutants and analysis of endocrine disruptors);
- analyses to check for compliance with requirements concerning chemical products used in the process.
DRINKING WATER CONTROL STANDARDS
The reference standards for the quality control of water for human consumption are directive 98/83/EC and the Italian Legislative Decrees 31/2001 and 27/2002 that implemented it. Such standards require that two types of chemical-physical and microbiological analytical control be performed:
The standard lists the parameters to be monitored and attributes a “parametric value” to each of them. This value constitutes a limit. If it is exceeded, appropriate corrective action must be taken. The parameters to be monitored and which must be compliant are detailed in Annex I of Italian Legislative Decree 31/2001. For parts A (microbiological parameters) and B (chemical parameters) of this Annex, non-compliance with the parametric value triggers a procedure outlined by the local health authority (art. 10 of Italian Legislative Decree 31/2001 later amended by Italian Legislative Decree 27/2002). This involves immediate restoration of water quality by the provider. Part C of Annex I shows, instead, a series of parameters defined as “indicators”. As before, this group of parameters has values that must be complied with. However, in the event of non-compliance the course of action is different (see art. 14 of Italian Legislative Decree 31/2001 later amended by Italian Legislative Decree 27/2002). In this case the regulation requires that the Agenzia Territoriale Regionale after hearing the opinion of the Local Health Authority on the possible risk to human health, defines the tasks needed to restore water quality but, unlike procedures for parameters in parts A and B, correction is not an "emergency" issue.
In October 2015 Annexes II and III of directive 98/83/EC were amended by EU Directive 2015/1787 that introduced the Water Safety Plans methodology. More specifically, Annex II introduces a certain degree of flexibility in the execution of checks, also allowing for a reduction in frequency if risk management/assessment is performed as per international standards, namely EN 15975-2 concerning water supply safety and WHO guidelines (Water Safety Plan). In June 2017 the Italian Ministry of Health issued a decree implementing the directive.
Moreover, in 2016, Italian Legislative Decree 28 was published, which implements EURATOM directive 2013/51 concerning the radiological characterisation of water for human consumption. This standard (which replaces Italian Legislative Decree 31/2001 on radiological parameters) states that providers must check for radioactive substances by monitoring a series of indicator parameters. The standard defines their relative values. In August the Ministry of Health issued a decree, drawn up in partnership with the Istituto Superiore di Sanità (Higher Institute of Health) that includes technical-scientific working guidelines. The currently applied Hera control plan incorporates comparisons with Arpae Piacenza and the local health authority to share radio-chemical parameter sampling and analysis methods.
New legislation includes the Ministerial Decree of 14 November 2016, co-issued by the Ministry of Health and Ministry of the Environment and Protection of Land and Sea. The latter establishes, for water intended for human consumption, a new hexavalent chromium chemical limit of 10 µg/L. The Ministry of Health, with the Ministerial Decree of 6 July 2017, extended the date of entry into force of the Decree of 14 November 2016 set at 31 December 2018, postponing it to 31 December 2019.
Until then, therefore, the parameter defined in Legislative Decree 31/2001 for the total chromium parameter remains applicable.
Italian Legislative Decree 31/2001 sets the chromium parameter limit at 50 µg/L (this limit, however, refers to total chromium). In nature, chromium is found in two main forms: hexavalent chromium (chromium VI) and trivalent chromium (chromium III). Trivalent chromium is an essential micronutrient, necessary for the correct metabolism of sugars in the human body. Hexavalent chromium, instead, has been classified as carcinogenic and genotoxic for humans on the basis of epidemiological studies that have shown an association between inhalation exposure to hexavalent chromium and lung cancer (source: IARC report- International Agency for Research on Cancer).
Studies on the effects of drinking contaminated water are limited and the consequent effects are uncertain; nevertheless, the European Food Safety Authority (EFSA) has detected a potential risk of neoplasm associated with exposure to hexavalent chromium in drinking water, especially in the young (children aged 0 - 10) (source: Ministry of Health).
The historical set of analytical results concerning drinking water supplied by Hera S.p.A. indicates that, in 2015-2018, total chromium never exceeded 10 µg/L. Consequently, there is no risk of exceeding the hexavalent chromium parameter
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