Blog Articles

Water Chemistry

21 December 2020

1. How can I evaluate the hardness of my water?

Waters are usually classified according to their degree of hardness, as follows:

  • Soft Water 0-75 mg/L (CaCO3)
  • Moderately hard water 75-150 mg/L (as CaCO3)
  • Hard water 150-300 mg/L (CaCO3)
  • Very hard water >300 mg/L (CaCO3)

Water hardness is caused by the presence of metal cations, of which the calcium and magnesium ions are the ones who contribute on a larger scale.

  • Hard waters are, in general, waters that require considerable amounts of soap to foam, and that form scales in boilers and other materials when they are heated.
  • When the water hardness is high, it leads to the formation of bothersome and disturbing deposits. Soft waters can cause corrosion because they do not form protective carbonate deposits in plumbing.
  • From a sanitary point of view, hard waters do not have any drawbacks. Even though there are some epidemiological studies that seem to show that there may be an inverse relationship between water hardness and heart diseases associated with other social and climatic factors, this has not yet been fully proved, according to World Health Organization (WHO).

2. Why is tap water white sometimes?

The white colour is due to the presence of dissolved air in the water, caused mainly by manoeuvring in the Distribution Network. This is timely and temporary, but it should be noted that the water is fit for consumption.

We advise you to let the water stand for a few minutes.

3. What is the volume of water necessary for a physical-chemical analysis for human consumption?

You should collect about 500ml of water. See sampling procedure on the menu – SERVICES.

4. How important is chlorine?

Chlorine is a disinfectant used in water treatment, which aims to ensure its microbiological quality, without causing problems for public health.

5. Which Legislation regulates the treatment of water for human consumption?

The legislation for water treatment is the Decree-Law no. 306/2007 of August 27th.

6. What is the water pH?

The pH (hydrogen potential) reflects the acidity or basicity of the water.

The pH scale comprises numbers between 0 and 14 – a pH of 7.0 indicates a neutral solution; if it is below 7.0, it indicates an acidic solution; and if it is above 7.0, it indicates an alkaline solution.

7. What can influence water features?

Age and plumbing conservation status can change the water’s characteristics, namely its taste, smell and colour. The water temperature may also affect its taste. Cool water is more pleasing to the palate.