WHAT IS IT?
Heavy metals are a group of chemical elements with high density. They are generally toxic to humans, and among those most likely to be found in water are mercury, nickel, copper, lead, and chromium.
HOW DOES HEAVY METAL POLLUTION OCCUR IN WATER?
The increased concentration of these compounds in water is primarily due to point source pollution from industrial or mining sources. Leachate from landfills or wastewater discharges can also be a source of contamination. It should also be noted that in some cases, water undergoes a natural enrichment process with heavy metals as it passes through aquifers formed by rocks that contain these metals in their composition.
WHAT ARE THE LIMITS SET FOR THE PRESENCE OF HEAVY METALS IN DRINKING WATER?
Heavy metals are generally toxic to humans, and their bioaccumulative nature (they cannot be eliminated by the body) means that the concentrations allowed in drinking water by current legislation (RD 140/03) are very small.
Since there are several elements involved, we will show as an example a list with the limits established in drinking water for the main heavy metals:
Mercury: 1 microgram/l
Nickel: 20 micrograms/l
Copper: 2 milligrams/l
Lead: 25 micrograms/l
Chromium: 50 micrograms/l
HOW CAN HIGH CONCENTRATIONS OF HEAVY METALS IN WATER BE PREVENTED?
It should be noted that the presence of these elements is very rare and if they do appear, they do so in trace amounts, that is, in concentrations well below the legal limit stipulated for drinking water.
Whenever possible, water sources used for supply are those that meet the concentration limits established by current legislation. However, there are areas where this is not possible due to the widespread presence of high concentrations of certain heavy metals in the groundwater or surface water. In these cases, secondary treatment, permitted by the health authority, is carried out to remove the metal.
