The Characteristics of Water Quality
The last thing we did last week , was to watch Annie Leonard’s video. In the video Annie showed how the drinking of tap water could greatly reduce environmental problems, and that in fact in many cities around the world the quality of tap water is just as good – or as bad- as that of bottled water.
But what can we do if we have doubts about the quality of the tap water quality we receive?
The first thing we can do is to contact our local water agency and ask for a copy of the water analysis. (which is often available online)
Being aware of the characteristics of water as specified by law can give us a better understand of the analyses we ask for and of the labels on the different brands of bottled mineral water.
In the published analysis, the values for at least the following data, should be given:
H+ ion activity (ie water pH): generally a value in the range 6.5 ≤ pH ≤ 9.5.
Conductivity
The quantity that defines the ability of a water to conduct electricity. Water in its purest form does not have this capacity, the specific electrical conductivity is determined by electrolytes, that is, by the presence of dissolved particles with an electric charge, positive and negative ions. This parameter is therefore directly proportional to the content of dissolved ions, but is not able to give any indication of their nature. It can instead be correlated with the TDS (Total Dissolved Solids), parameter which represents the total content of the dissolved substances, after having evaporated all the water but also after having treated the residue at the temp. of 180 ° C. Normally the maximum recommended value is 1500 mg / L.
Turbidity
This term refers to the decrease in the water´s clearness caused by suspended solid or colloidal substances. The presence of turbidity in water containing iron and manganese is caused by their compounds which in certain situations precipitate as solids.
Because of the potential association of elevated particles to bacterial or microbiological contamination, the level of turbidity is used as a red flag for potential microbiological contamination or secondary water quality problems with the water. The primary recommendation is that the turbidity levels not exceed 1 ntu.
Calcium (hardness)
With the term water hardness, a parameter to which the classical phenomenon of limestone formation refers, we mean the content of calcium and magnesium salts. The hardness is generally expressed in French degrees (1 ° F corresponds to 10 mg / L of calcium carbonate).
Main components: fluorides, chlorides, sulphates, sodium, potassium and bicarbonates
In practice, water contains a certain amount of dissolved substances that are closely related to the rocks and minerals it has encountered along its course from its source to its final destination.
Their concentration is generally at the level of (mg / L). The Maximum Contaminant Level (MCL) may vary, but as far as I see they are around 200/250 mg / L.
Nitrates (nitrogenous substances)
This definition refers to the inorganic chemical species containing nitrogen such as ammonium, nitrite and nitrate ions.
Generally, the value for ammonium is 0.5 mg / L, for nitrates and nitrite the values are generally between 50 and 0.50 (0.10) mg / L respectively.
Iron and manganese
Their permitted value is generally 200 μg / L for iron and 50 μg / L for manganese. Their origin is due to exclusively natural reasons and can not be associated with human activities.
Other chemicals
Many substances can be contained in the water both for natural reasons and due to pollution caused by human activity. In particular, the presence of these substances is characterized by very low concentrations, the MCL is between μg / L (micrograms per liter, equivalent to 10-6) and ng / L (nanograms per liter, equivalent to 10 -9).
These substances can be divided into inorganic substances, such as heavy metals (Cadmium, Chrome, Lead, Nickel, Copper, Barium, Zinc, Mercury, Antimony, Selenium and Vanadium) and not metals (Arsenic). It is important to note that while some of these elements are hazardous above certain levels, some, like selenium, copper and chromium, are essential nutrients at lower levels. Others, like lead and arsenic, are undesirable at any level.
And organic substances, including some Volatile Organic Chemicals (VOCs), such as Trichlorethylene and Tetrachlorethylene, aromatic solvents such as benzene, and other substances such as polycyclic aromatic hydrocarbons (PAHs) and pesticide molecules (insecticides, herbicides, fungicides, etc.).
Organic substances deriving from disinfection are also examined, among the most known are trihalomethanes, and inorganic, chlorite and bromate, which are the products of the reaction of chlorine dioxide and ozone.
In general, heavy metals derive from natural problems, for example , the excessive mineralization of water in the subsoil, can cause a migration of these substances into the water. Contamination from organic substances, is instead caused by pollution generated, more or less consciously, by human activity.
The “chemical parameters” are between the ng / L and the μg / L. The values allowed for these substances are obtained from long-term experiments conducted on guinea pigs subjected to known and increasing amounts of the substance examined. *
Chlorine
Is clearly not contained in water in its natural state, but is added during sterilization treatment or, more often, used to maintain the characteristics of microbiological purity in the distribution network. In general, two different substances are used for this operation: hypochlorite and chlorine dioxide. Generally the concentration level values for these substances is between 0.10 ¸ 0.20 mg / L, suitable to guarantee a perfect microbiological quality. *
Microbiological parameters
The microbiological tests are designed to ensure that the water does not contain pathogenic micro-organisms.
Other parameters indicated as accessories such as algae, the anti-E. coli bacterium, helminths, pathogenic enterobacteria, enteroviruses, fungi, protozoa, Pseudomonas aeruginosa and pathogenic Staphylococci can also be searched for.
Under the item “other chemicals”, I personally find it reasonable, to ask your local Water Board what benchmark parameters indicators they have with respect to the daily intake, I would also ask if they are looking for even more subtle and recent contaminants such as PFAS (perfluoroalkyl substances) and glyphosate.
Normally, on any website of a water agency we should also find information about the body of water which is used as the water supply, the distribution of tanks and municipal storage basins and a lot of other information.
However, if the agency refuses to provide more detailed analyzes we have, in my opinion, two possibilities:
-One, to start a petition, along with other citizens in order to make this happen.
-Two, to request the analysis at a private laboratory, perhaps trying to share the cost involved with other people who receive water from the same source and are as interested as we are. In this case, we must explicitly request what we want to look for, according to the area in which we live and what could infiltrate with more possibilities in our waters.
For those of you interested in launching a petition, I would be pleased if you would like to share your experiences, motivations and ideas.
In the town where I live, I have entered into communication with the local water agency. After a careful study of the legislation here in Spain (Real Decree 140/2003) and the European Drinking Water Directive, I asked a series of questions. The director of the agency replied by attaching documents relating to materials and characteristics of public installations, sodium hypochlorite (Sodium hypochloride), microbiological and chemical analysis data of the control laboratory and the report with the complete analysis of the following parameters:
Indicator parameters – Microbiological parameters – Chemical parameters – Volatile organic compounds – Trihalomethanes – Volatile aromatic dissolvents – Polycyclic aromatic hydrocarbons – Organochlorine pesticides, Triazines and derivatives.
Therefore, I now wish to CALL for HELP! I call upon people of good will with skills in water quality, chemical analysis, interpretation of data on water quality parameters, I believe that a civil engineer specialised in water-based projects could be very familiar with these issues, and could help me to analyze and interpret these data and understand if, beyond the maximum levels and the substances sought, we can work together to ask local agencies to take measures to further improve the quality of public water and water management plans.
In the next post I will analyse the different possibilities of improving the quality of public water , which arrives in our homes or workplaces (filters and water depuration). Stay tunned and we will continue to explore together.
Wishing you all a great new day.
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