Controlled ParametersControl & Quality of Water
IMPORTANCE OF CONTROLLED PARAMETERS
Joint Ministerial Decision No. Γ1(δ)/ΓΠ οικ. 67322/Government Gazette B 3282/19.09.2017, in compliance with Directive 98/83/EC on the quality of water intended for human consumption, as amended, determines the frequency and types of analyses depending on the daily volume of water distributed or produced.
During the performance of minimum controls in the Laboratories (Group A parameters set out in the Legislation) on a daily basis and throughout the year, samples are tested from water supply sources, from the Water Treatment Plant, which includes both the incoming water from the Aliakmonas River, as well as the intermediate treatment stages and the outgoing water from the plant, and also from the distribution network in terms of parameters like odour, taste, turbidity, colour, pH, conductivity, chlorides, aluminium and microorganisms.
Furthermore, an annual programme is implemented in order to monitor drinking water in terms of all the parameters in Group B of the applicable legislation. Sixteen (16) sampling procedures are carried out annually and the samples are tested in terms of parameters including, inter alia, heavy metals and organic compounds (pesticide residues, chlorination by-products, solvents, polyaromatic hydrocarbons, odour and taste compounds, etc.).
An important factor determining the suitability of drinking water is the lack of pathogenic microorganisms. Our Laboratories perform microbiological tests that include the detection and measurement of total coliforms and E.Coli, the detection and measurement of enterococci, the measurement of the total number of aerobic microorganisms at 22οC and at 36οC, and the detection and measurement of Clostridium perfringens. The samples are taken from points of the distribution network and from points where water is made available to consumers.
Furthermore, in collaboration with the Hygiene Laboratory of the School of Medicine at Aristotle University of Thessaloniki and the University of Patras, cooperation programmes on the quality of drinking water are implemented through microbiological analyses of water samples from the water supply network and springs.
| Parameter | Maximum permissible limit based on the legislation | Analysis frequency | Information on each parameter |
| Odour | Accepted by consumers and without abnormal change | Daily | Drinking water must be odourless. A specific odour threshold has not been set, however it has been determined that it must be accepted by consumers and must not present any abnormal change. |
| Taste | Accepted by consumers and without abnormal change | Daily | Drinking water must be tasteless. A specific taste threshold has not been set, however it has been determined that it must be accepted by consumers and must not present any abnormal change. |
| Parameters | Legislative patrametric value | Sampling Frequency | Information for any parameter |
| Turbidity | Acceptable to consumers and no abnormal change | Daily | Turbidity is a measure of the suspended particles in the water. Directive 98/93/ EC does not specify a specific threshold, but it stipulates that it should be acceptable to consumers and that it does not present an abnormal change. It is an important parameter of aesthetic acceptance by consumers and functional suitability. Large turbidity values adversely affect the effectiveness of disinfection. |
| Conductivity | 2500 μS/cm | Daily | This parameter is a measure of the concentration of dissolved salts in water. Therefore, it can not be directly linked to health. However, it can be considered as an important functional parameter. |
| Colour | Acceptable to consumers and no abnormal change | Daily | Color appearance is undesirable for drinking water.
It may be derived from dissolved compounds, plant origin, organic or inorganic (iron, salts). Colored water is not always dangerous. However, its origin must be sought by chemical examination. There is no permissible limit for water color, but it is stated that it should be acceptable to consumers and not present unnatural change. |
| Hydrogen ion concentration pH (expressed in pH units) | > 6.5 and < 9,5 | Daily | It is a measure of the balance of acid and alkaline compounds dissolved in water. We control the pH, because if it is too acidic, water can cause corrosion of the metal pipes, and if it is too alkaline the water has a tendency to deposit in the pipes. |
| Free residual chlorine | Legislation does not set an upper limit | Daily | Chlorine is used as a disinfectant in the distribution and treatment of water. By disinfection we mean the destruction of pathogenic microorganisms contained in water. The chlorination of water is done in such a way that a small amount of residual chlorine is left to deal with infections when distributing water to consumers. This small amount of residual chlorine is completely HARMLESS for human health as it is neutralized by saliva and gastric juices. |
| Ammonium | 0,50 mg/l | 16 analysis /year/ within a supply zone | It is a parameter of particular importance because it is an indicator of fecal contamination while it reacts with the chlorine added to disinfect it by reducing its effectiveness. |
| Nitrite | 0,5 mg/l | 16 analysis /year/ within a supply zone | Nitrite ions are an intermediate stage of ammonia oxidation and are unstable in the environment. Their presence in the water indicates recent pollution. |
| Chloride | 250 mg/l | Daily | They are widely used as sodium, potassium and calcium salts. They come from the corrosion of the rocks. Their sudden increase in water indicates potential contact with seawater or even possible pollution by sewage. |
| Nitrate | 50 mg/l |
16 analysis /year/ within a supply zone |
Nitrate anions are products of the final ammonia oxidation step. High concentrations are due to fertilizers, waste and animal or human waste. Their presence in the water indicates an earlier pollution. |
| Iron (total) | 200 μg/l | 16 analysis /year/ within a supply zone | The presence of high concentrations of iron in drinking water is undesirable for aesthetic reasons. Iron-containing water leaves stains when washing on clothes. |
| Magnanese | 50 μg/l | 16 analysis /year/ within a supply zone | Sometimes it is associated with stain complaints when washing clothes with a washing machine. Manganese salts can give the water an unpleasant metallic taste. |
| Sulphate | 250 mg/l | 16 analysis /year/ within a supply zone | High concentrations of sulphates may enter the water by fertilizers or industrial waste. |
| Total organic carbon (TOC) | No abnormal change | 16 analysis /year/ within a supply zone | This is the total carbon that is bound to organic compounds and is an indicator of the organic load of water. |
| Fluoride | 1,5 mg/l | 16 analysis /year/ within a supply zone | High concentrations of surface water may result from industrial contamination (aluminum treatment, glass industry, phosphate fertilizers). In small amounts it is important for the development of teeth and bones. |
| Cyanide | 50 μg/l | 16 analysis /year/ within a supply zone | They may occur in the water as waste from steel, plastic and fertilizer industries. |
| Bromate | 10 μg/l | 16 analysis /year/ within a supply zone | These are by-products of water disinfection with ozone. |
| Parameters | Legislative patrametric value | Sampling Frequency | Information for any parameter |
| Aluminium | 200 μg/l | Daily | Aluminum is checked because it is used as a flocculant (PAC) in the surface water treatment plant to reduce suspended solids, algae and organic load. |
| Antimony | 5 μg/l | 16 analysis /year/ within a supply zone | Antimony in natural water is found in trivalent or pentavalent form. It is used in semiconductors, batteries, ceramics and ammunition. |
| Arsenic | 10 μg/l | 16 analysis /year/ within a supply zone | It can enter the aquifer through industrial pollution or naturally through the passage of water from volcanic rocks. |
| Selenium | 10 μg/l | 16 analysis /year/ within a supply zone | It is a basic trace element for humans. Internationally, the concentration of selenium in drinking water is less than 10 μg / l. |
| Mercury | 1 μg/l | 16 analysis /year/ within a supply zone | Mercury is used in electrical appliances, dental amalgams, pesticides and pharmaceuticals. |
| Boron | 1 μg/l | 16 analysis /year/ within a supply zone | It can enter the water by dissolving sodium borate or calcium borate in the soil. |
| Cadmium | 5 μg/l | 16 analysis /year/ within a supply zone | A source of environmental pollution from cadmium may be waste from phosphate fertilizer industries. It is still used in water pipe welding materials. |
| Chromium | 50 μg/l | 16 analysis /year/ within a supply zone | Chromium is found in nature in hexavalent and trivalent form. The hexavalent form is more soluble making it dispersed in water systems easier. Chromium and its salts are used in tannery, paints, glass and anti-corrosion alloys. |
| Copper | 2 μg/l | 16 analysis /year/ within a supply zone | Corrosion of copper pipes may lead to copper in the drinking water. |
| Lead | 10 μg/l | 16 analysis /year/ within a supply zone | High concentrations may arise from industrial pollution. |
| Nickel | 20 μg/l | 16 analysis /year/ within a supply zone | High concentrations of nickel can be found in drinking water from industrial pollution or from nickel-rich rocks. |
| Sodium | 200 mg/l | 16 αναλύσεις /έτος/ ζώνη παροχής νερού | Sodium is an essential element in many physiological mechanisms of the body. Domestic water softening devices may cause an increase in the concentration of water. |
| Parameters | Legislative patrametric value | Sampling Frequency | Information for any parameter |
| Escherichia coli (E. coli) | 0 / 100ml | Daily | It is considered the main indicator of fecal infection. Its presence in water is an indication of recent pollution from feces of warm-blooded animals. |
| Coliform bacteria | 0 / 100ml | Daily | More general fecal infection index. |
| Colony count 22οC | No abnormal change | Daily | The number of colonies at an incubation temperature of 22 ° C is of relatively low health value but useful as an indicator of water treatment efficiency (flocculation, precipitation, filtration). |
| Colony count 36οC | No abnormal change | 16 analysis /year/ within a supply zone | The increase in the number of colonies at an incubation temperature of 36 ° C from the usual measured values can be used as evidence of an increase in pollution, and mainly of fecal origin by humans or animals. |
| Clostridium perfingens | 0 / 100ml | 16 analysis /year/ within a supply zone | It is looked for when water comes from or is affected by surface water. It is used as an index for the effectiveness of water treatment. |
| Enterococci | 0 / 100ml | Daily | They rarely multiply in water. Their presence is evidence of water contamination with faecal matter, especially older ones. |
| Parameters | Legislative patrametric value | Sampling Frequency | Information for any parameter |
| Benzene | 1 μg/l | 16 analysis /year/ within a supply zone | It is mainly used in the petroleum industry as an additive for unleaded petrol to improve the number of octanes. Any dispersion of benzene in water may be due to the disposal of petroleum or chemical waste. |
| 1,2-dichloroethane | 3 μg/l | 16 analysis /year/ within a supply zone | It is used as an intermediate in the manufacture of chlorinated solvents and as an extractor for organic materials. It can be found in water due to industrial pollution. |
| Trihalomethanes — total | 100 μg/l | 16 analysis /year/ within a supply zone | Trihalomethanes (THMs) are by-products of chlorine disinfection. Four compounds are tested: chloroform, bromoform, dibromochloromethane and bromodichloromethane. |
| Tetrachloroethene and Trichloroethene | 10 μg/l | 16 analysis /year/ within a supply zone | They are widely used in the paint and varnish industry as solvent. |
| Pesticides | 100 ng/l | 16 analysis /year/ within a supply zone | Pesticides (mainly include insecticides, herbicides and fungicides = Plant Protection Products) are organic compounds that have been produced to act as biocides towards a variety of organisms (pests). The main activity that leads to inflows into the aquifer is agriculture. |
| Polycyclic aromatic hydrocarbons | 100 ng/l | 16 analysis /year/ within a supply zone | PAHs are formed as incomplete combustion products of organic compounds, but can be synthesized by bacteria, algae and plants. They have low solubility in water and are strongly adsorbed on suspended solids. |
| Benzo(a)pyrene | 10 ng/l | 16 analysis /year/ within a supply zone | Benzo-α-pyrene belongs to polycyclic aromatic hydrocarbons. Because it is related to the likelihood of cancer, the EU Directive requires it to be measured separately. |
