Over 1 billion pounds of herbicides and other chemicals for controlling different pests are used yearly in the United States. This heavy usage increases the chances of herbicides contaminating your drinking water.
Reverse osmosis is popular because it can remove several water contaminants. The RO membrane cannot completely remove all herbicides on its own. However, because RO systems incorporate activated carbon, most modern RO systems can significantly reduce herbicides from your water.
In this article, we look at different types of herbicides and how they get into our water. We also discuss how effective reverse osmosis systems are at removing herbicides, the specific quantity of herbicides removed by reverse osmosis, and how to test your water for herbicides.
Herbicides
Herbicides are chemicals specifically designed to control or kill unwanted plants (or weeds). They are used in agriculture, landscaping, and gardening to manage vegetation and promote the growth of desired crops or plants.
Herbicides can be selective, targeting specific types of plants, or non-selective, killing any plants they come into contact with. They are primarily used to prevent weed competition, which can negatively impact crop yield and overall plant health.
Some of the most commonly used herbicides in the United States are glyphosate, atrazine, alachlor, metolachlor, and 2,4-D.
Of the herbicides used in the United States every year, the majority – about 90% – are used by farmers for agricultural purposes.
These chemicals may be carried by runoff and erosion from the agricultural fields where they are used, and mixed in with bodies of surface water such as streams, rivers, lakes, etc. They can also leach into groundwater such as wells and springs.
Atrazine is the second most-used herbicide in the country and is the most commonly found in groundwater and surface water.
You can read more about how to specifically remove atrazine from your water here.
Herbicides could also get into water when these chemicals are stored improperly or are disposed of incorrectly.
On exposure to the environment, these herbicides often break down into other chemical forms known as degradation products. Sometimes, these herbicides may be present in these bodies of water as their degradation products.
These chemicals can pose serious health challenges if present in your drinking water.
Pesticides
Pesticides are a broader category of chemicals used to control a wide range of pests. This includes insects (insecticides), rodents (rodenticides), fungi (fungicides), and other harmful organisms.
Pesticides are commonly used in agriculture to protect crops from pests that can damage or destroy them. They are also used in homes and public areas to control pests that may transmit diseases or cause property damage.
The type of pesticides used has evolved over the last 100 years. Heavy metals and other toxic substances such as lead, mercury, arsenic, and copper were formerly used traditionally as pesticides.
These substances were not very soluble in water, and their residues entered foods at concentrations harmful to human health and the environment.
To solve the problem that these substances posed, compounds called chlorinated hydrocarbons and other synthetic chemicals were introduced.
But these substances also accumulate in toxic concentrations in food.
To avoid the negative effects of these pesticides on human health and the environment, new types of pesticides were introduced. These new pesticides are carbamates and organophosphates.
Unfortunately, these modern pesticides are soluble in water and often find their way into water bodies. Water from these contaminated bodies may serve as drinking water sources for homes.
Does Reverse Osmosis Remove Herbicides?
Reverse osmosis is a very efficient water filtration system and can remove several contaminants from water. However, reverse osmosis cannot, on its own, completely remove herbicides from water.
Reverse osmosis works by pushing water molecules under pressure through a semi-permeable membrane with numerous tiny pores.
During this process, contaminants with larger molecules than water are left behind because they are too big to pass through the pores.
As a result, contaminants are filtered out, and clean, purified water is produced by the reverse osmosis filter.
Many herbicides and pesticides have larger molecules that cannot pass through the tiny pores of the RO membrane. As a result, these contaminants are effectively removed, and the purified water is collected on the other side of the membrane, free from herbicides and pesticides.
However, this process is not 100% efficient because some contaminants have molecules smaller than water.
Such substances will slip through the pores of the filtration membrane, remaining as contaminants in the water.
Some herbicides fall into this category of substances that are too small to be filtered out by reverse osmosis.
Fortunately, most reverse osmosis systems do not rely on the membrane alone. They also have pre-filters or post-filters made of activated carbon.
Activated carbon is a filtration media that efficiently removes herbicides and other chemicals that may contaminate water.
There are different types of reverse osmosis systems for domestic use. Some come with tanks where they store filtered water. As this water gets used up, the system automatically filters more water and transfers it into the tank for storage.
Some RO systems are tankless. These tankless systems don’t have storage compartments to keep already filtered water. Instead, they filter water on demand.
Domestic RO systems may also come with added features such as ultraviolet light to effectively remove any bacteria in the water.
Regardless of the type of RO system you get, what determines if it can effectively remove herbicides from your water is if it has a suitable activated carbon pre-filter or post-filter.
Before buying your reverse osmosis filtration system, keep in mind that there are a variety of herbicides. One RO system may not be able to remove the whole spectrum.
If you have a particular herbicide contaminant you are worried about, check to be sure that the RO system has been tested against NSF standards and certified to remove that specific herbicide.
When in doubt, an email or a call to the manufacturer will go a long way in getting you definite answers.
Removal of Herbicides by Reverse Osmosis
Below is a table that contains some of the common herbicides and the amount of these herbicides removed by reverse osmosis.
| Herbicide | % Reduction |
|---|---|
| 2,4-D | 98% |
| Alachlor | >71% |
| Atrazine | 95% |
| Bentazon | >99% |
| Cyanazine | >98% |
| Endrin | 99% |
| Glyophosate | 99% |
| Heptachlor | 98% |
| Linuron | >99% |
| Metolachlor | 80% |
| Metribuzin | >58% |
| Pentachlorophenol | >99% |
| Simazine | >97% |
| Trifluralin | 99% |
How Do I Know If My Water Has Herbicides?
It is difficult to detect the presence of herbicides in your water by its smell, look, or taste. This is especially true if the herbicides are present in small quantities.
If the herbicides are present in large enough quantities, your water may have a distinctive chemical taste. There are two ways to see if there are herbicides in your water: 1) Pesticide Test Strips 2) Certified Laboratory Testing
1. Pesticide Test Strips
The first option is to use pesticide test strips.
Pesticide test strips usually test for organophosphates and carbamates, both of which are the compounds found in many popularly used herbicides and insecticides.
These test strips are designed to detect the presence of pesticides on fruit and vegetables. If you think about it, many different fruit and vegetables are regularly sprayed with pesticides, so pesticide test strips can often detect if the food is contaminated.
However, the level of pesticides in drinking water is almost always much lower because of dilution. So, using pesticide test strips to test your drinking water may not be a great option and will probably not be very accurate.
To emphasize this point, many people who test regular supermarket-bought strawberries, which are known to be heavily sprayed with pesticides, often cannot detect anything at all using pesticide test strips.
However, if you want try testing your water then by all means give it a shot!
A typical pesticide test kit (Amazon example) comes with pesticide test cards, a color chart card, and sometimes, liquid reagents.
These tests are quick and easy to perform. You can do them at home by yourself.
Depending on the manufacturer, the test procedure may vary. So, you should follow the instructions accompanying your test kit.
Usually, the test is straightforward to perform, and the results can be ready within about 15 minutes. Once you’ve performed the test, you compare the color of the pesticide test card to the color chart card. These tests won’t be able to determine the type or concentration of the pesticide, but they may indicate if there is high or low amounts in your sample.
2. Certified Laboratory Testing
This method is preferred for the detection of herbicides in water because of its high level of accuracy.
It involves sending a water sample to a certified water testing laboratory to check for herbicides.
For this, you need to order a lab test kit. We highly recommend the Tap Score Herbicides Water Test. The test kit contains everything you need to properly collect a water sample, and send it to the lab.
In the lab, specialized equipment and reagents are used to analyze ten commonly used herbicides including:
- 2,4,5-T
- 2,4-D
- 2,4-DB
- Acifluorfen
- DCPA (Dacthal)
- Dalapon
- Dicamba
- Dichlorprop
- Dinoseb
- Silvex
Once the analysis is done, the lab will send you a detailed report of the results via email. Turnaround time is about ten days.
If your home is located near areas of agricultural activity or areas with a history of herbicide use, you should regularly get your water tested for herbicides.
Herbicide Testing For Private Well Owners
Private well owners are recommended to test their water at least once a year for herbicides and pesticides to ensure its safety.
The best time of year to test is after a heavy rain (typically in the fall or spring) as it’s the most likely time the groundwater or aquifer will be recharged with water (and possible agricultural runoff).
If your well is within a 1/4 mile of current or former orchard or farmland it’s always a good idea keep up with annual testing.
If your buying a new home with a well, it’s a good idea to get test the water quality so you can make an informed decision before you purchase.
Monitoring water quality and conducting appropriate tests can help identify any potential pesticide and herbicide contamination in the well water.
