Pesticides are chemical substances intended to kill, repel, or control harmful organisms: insects, weeds, fungi, bacteria, and animals. They are used in many fields, from agriculture to forestry to gardening. These chemicals can end up in the tap water we consume daily.
How do pesticides contaminate our drinking water? What treatment methods are in place? In this article, we will explore these points in detail, as well as possible solutions to ensure access to safe drinking water in your home.
What are the main sources of pesticides in water?
While intensive agriculture is a major source of water contamination by pesticides, pollution of urban and peri-urban waters also represents an invisible danger.
Intensive, invasive, and polluting agriculture
In France and around the world, intensive agriculture has become the norm. This industrial approach depletes soils and severely disrupts natural ecosystems.
To 'protect' their crops from pests that have emerged due to these environmental upheavals, farmers heavily rely on chemical pesticides, often preventively. Thus, intensive agriculture is the main source of pesticides in tap water.
Contamination of urban and peri-urban waters, a significant scourge
Urban and peri-urban areas are not spared from pesticide contamination.
Certainly, the use of glyphosate-based herbicides is now banned for amateur gardeners. However, their sale online remains possible, allowing uncontrolled and potentially dangerous use.
Moreover, public authorities, such as municipalities, commonly use insecticides in stagnant water to combat mosquitoes. These products then end up in wastewater, thus contributing to pollution.
How do pesticides contaminate water sources?
Here are the different pathways of contamination of water sources by pesticides:
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Rainwater runoff: Any phytosanitary product applied to the soil can be carried by rainwater to watercourses and groundwater.
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Infiltration into the soil: On permeable soils or in cases of intensive use, pesticides can infiltrate the ground and reach groundwater, thus contaminating sources of underground water.
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Use of pesticides in gardens and green spaces: The pesticides used by individuals and communities for maintaining gardens, parks, and sidewalks can seep into the soil and rainwater, subsequently contaminating watercourses.
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Wastewater Management: Pesticides present in domestic and industrial wastewater may not be completely removed by treatment plants and can contaminate our rivers and lakes.
How are pesticides removed from drinking water?
Water extracted from various sources (groundwater, rivers, lakes) is not yet suitable for consumption. It must undergo rigorous treatment to meet quality standards and satisfy consumer needs.
This treatment, implemented by water service companies, adapts to the characteristics of the water resource and the current regulatory requirements. It includes several key steps:
Pretreatments, to rid the water of its initial undesirable elements
For heavily loaded waters, pre-sedimentation allows for the separation of coarse suspended materials (clay, silts...).
Pre-oxidation (use of ozone) also helps to eliminate ammoniacal nitrogen, iron, and manganese. It reduces tastes, colors, and odors, and improves the efficiency of subsequent treatments.
Clarification, to make the water clear
This step is essential to eliminate:
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suspended particles (sand, silt, organic debris...),
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colloids (fine clays, bacteria...),
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and a portion of dissolved substances (organic matter, salts...).
That said, the different clarification techniques include:
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Coagulation-flocculation: Addition of a coagulant to destabilize colloids and form aggregates (flocs) that will then be separated from the water.
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Sedimentation or flotation: Separation of flocs by natural sedimentation or by rising with air bubbles.
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Filtration: Removal of remaining fine particles through a sand bed.
Refining, to perfect the quality of the water
Various treatments improve the organoleptic qualities of water (taste, odor, clarity), including:
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Adsorption on activated carbon: Activated carbon captures dissolved organic compounds and certain micropollutants, such as pesticides, hydrocarbons, and heavy metals found in explosives.
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Stripping: It involves removing dissolved gases and volatile compounds by injecting a gas (air, oxygen).
Membrane filtration, a cutting-edge technology
Used in addition to or in place of clarification, membrane filtration allows for the retention of even finer particles.
Here are the technologies used:
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Microfiltration: Retains bacteria, parasites, yeasts, and particles responsible for turbidity.
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Ultrafiltration: Also eliminates viruses and colloids.
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Nanofiltration: Retains calcium, as well as most pesticide-type pollutants and their metabolites.
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Reverse osmosis: The most efficient process, used for seawater desalination and the production of ultra-pure water.
Disinfection, to neutralize pathogens
An essential step to ensure consumer health, disinfection eliminates pathogenic viruses and bacteria present in water.
This involves different methods:
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Disinfecting agents: Chlorine, chlorine dioxide, or ozone.
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Ultraviolet treatment: Use of UV rays to inactivate microorganisms.
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Membrane filtration: Some membranes have disinfecting properties.
Even after treatment against pesticides and their metabolites, a tiny amount of chlorine is added to the water to disinfect it throughout its journey in the pipes and prevent microbial proliferation.
The final treatment, for water that arrives intact to the consumer
Finally, the pH of the water is adjusted to prevent scaling or corrosion of the pipes. Similarly, aggressive or incrusting waters are neutralized or remineralized.
How do monitoring and regulations ensure the safety of drinking water?
As an essential element of our daily life, water is subject to strict and ongoing controls to ensure its quality and safety.
Two major players are involved in the control process in France:
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Legal entities responsible for the production or distribution of water (PRPDE): They implement a laboratory analysis and monitoring testing program defined by regulations. The results inform about the compliance of the water with current quality standards.
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Regional Health Agencies (ARS): They carry out independent health monitoring of water by taking samples at different stages of the production and distribution process.
Entities such as ANSES (National Agency for Food, Environmental and Occupational Health Safety) also play an essential role in the control system of the water supply in France.
Indeed, drinking water must meet rigorous requirements defined by regulations. Nearly 70 parameters are monitored, grouped into different categories:
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Microbiological: Absence of pathogenic germs that can cause diseases.
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Physico-chemical: Content of undesirable or toxic substances (nitrates, arsenic, pesticides, etc.).
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Organoleptic: Taste, odor, visual appearance.
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Radiological: Possible presence of radioactive substances.
Thus, there are quality limits for parameters presenting a direct or indirect risk to health. The maximum is 0.1 microgram per liter (µg/L) per individual substance, for most active substances of pesticides and their relevant metabolites.
This value is even lower (0.03 µg/L) for more toxic molecules such as aldrin, dieldrin, heptachlor, and heptachlor epoxide, which are currently banned.
What happens when the regulatory water quality limit is exceeded?
In France, a precise protocol governs the management of situations where analyses reveal pesticide and metabolite residues beyond quality limits. Improvisation and personal interpretation of the rules are prohibited.
As soon as an analysis detects an exceedance, the operator of the water distribution network is obliged to act without delay. He must:
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Immediately inform the mayor and the prefect
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Investigate thoroughly and communicate the conclusions to the authorities.
If the prefect deems that the water distribution presents a health risk, he orders the operator to implement the necessary directives: mixing of waters, interconnection to another network, etc.
He may also decide on a restriction of distribution, targeting certain uses or vulnerable population groups (babies, pregnant women...). Local health authorities then inform the population by all available means. In case of emergency, the distribution of water may be completely interrupted.
How can we reduce the presence of pesticides in water?
The presence of pesticides in drinking water is a major issue that affects human health and the environment; various solutions exist to reduce these contaminants.
Here are a few:
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The adoption of sustainable agricultural practices: Besides organic farming, precision agriculture should be encouraged, which involves adjusting the application of pesticides according to the actual needs of the crops. Agroforestry is also useful, as well as maintaining a permanent plant cover.
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The use of advanced water treatment technologies: For example, reverse osmosis allows for the removal of a wide range of contaminants, including pesticides, from drinking water. Other options include activated carbon adsorption, advanced oxidation, and membrane filtration.
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The involvement of individuals and communities: The public must be informed about the dangers of pesticides and sustainable alternatives. Citizen water quality monitoring programs also help better identify sources of contamination and target corrective actions.
How to eliminate pesticides and bacteria from tap water at home?
The various treatment processes undergone by tap water do not always guarantee total elimination of microorganisms. Furthermore, aging or weakened pipes due to work can create areas conducive to bacterial growth.
That's why filtration solutions exist to rid you of pesticides, and even eternal pollutants known as PFAS.
Gravity water filtration systems with activated carbon
A gravity water filter is an ingenious device that uses the force of gravity to purify water naturally and effectively. At Weeplow, this solution is available in different sizes to meet the needs of each household.
Once you pour water into the upper tank of the filter, it naturally flows through various filter cartridges, removing its impurities and contaminants.
Reverse osmosis filtration systems
They not only eliminate pesticides and herbicides but also prove formidable against a wide range of other harmful contaminants.
Substances effectively filtered by reverse osmosis include THMs (disinfection by-products) and VOCs (volatile organic compounds) found in solvents and gasoline.
However, this solution requires a larger initial investment and installation by a professional is recommended.
Protect yourself from pesticides trapped in your tap water!
Pesticides, used intensively in agriculture, can infiltrate soils and groundwater, thus contaminating drinking water sources. This exposes consumers to various types of health problems, including cancers.
That's why it is advisable to adopt effective treatment solutions, such as activated carbon adsorption, to eliminate pesticides in tap water at home.
Equipped with this cutting-edge technology, Weeplow water filtration systems are designed to effectively eliminate up to 99.999% of harmful contaminants. Browse our online store to find the solution that best meets your needs.
