Does Reverse Osmosis Remove Perchlorate from Water?
Written by: Gene Fitzgerald // Last Updated: Jun 2, 2023
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Perchlorate in drinking water poses a serious health concern. It has been discovered that it can impair thyroid function and cause iodide deficiency in humans, among other things.
What’s worse, Not every water filter can get it out of your water. This begs the question: Can reverse osmosis remove perchlorate from water?
This article has the answer. We’ve also shared other ways to remove perchlorate from water and explained how to test for perchlorate in the first place.
Contents
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Key Takeaways
- Reverse osmosis removes 95-99.9% of perchlorate in water.
- High-pressure reverse osmosis systems are more effective here. But even low-pressure systems as they are used in homes all around the US are highly effective at perchlorate removal.
Does Reverse Osmosis Remove Perchlorate from Water?
So, does reverse osmosis remove perchlorate from water?
Yes, reverse osmosis removes perchlorate from water. High-pressure reverse osmosis systems (pressure >150 psi) are so efficient that they reject up to 99.9% of perchlorate in water. On the other hand, low-pressure reverse osmosis membranes reject up to 95% perchlorate.
Note: An RO system may not be enough for water with extremely high levels of perchlorate. If your water contains high perchlorate levels, it’s advisable to add an ion exchange filter after the RO system for better results.
How Much Perchlorate Does Reverse Osmosis Remove and How?
Reverse osmosis works by passing pressurized water through a semipermeable membrane to separate it from impurities. In the process, contaminants of high molecular weight, such as perchlorates, get trapped on the membrane surface, while clean water passes over to the other side.
How much perchlorate a reverse osmosis membrane can remove depends on the level of pressure applied.
For instance, the EPA experimented using an RO system with pressure ranging from 20-90 psi. The system was able to reduce perchlorate levels in groundwater from a range of 125-2,000 μg/L down to 5-80 μg/L (which means it removed 96% of the perchlorate).
Still, this was done by a low-pressure RO membrane. High-pressure RO systems of about 150 psi can remove even higher percentages of perchlorate (up to 99.9%).
Other Methods to Treat Water and Remove Perchlorate
Asides from reverse osmosis, there are alternatives you can use for removing perchlorate from your water. Here are a few examples:
Anion Exchange
This process involves exchanging the negatively charged perchlorate ions in water with other harmless negative ions like chlorides or hydroxides.
During anion exchange, the contaminated water is pushed through a synthetic resin bed (usually packed in a column), where the perchlorate ions will be substituted. Clean water passes out at the other end of the resin bed. When the resins’ exchange sites have been exhausted, the beds are regenerated with fresh ions, and the waste water (containing extracted perchlorate) is discarded.
Biological Treatment
Certain types of bacteria developed in bioreactor basins are used as a biological treatment for perchlorates. The bacteria work by breaking perchlorate down to chlorides and oxygen in the presence of an electron donor (such as acetic acid, ethanol, hydrogen, etc.).
Usually, there needs to be an appropriate medium for the bacteria to thrive and grow. Packed bed reactors use static sand or plastic, while fluidized bed reactors use granular-activated carbon media or suspended sand to support the growth of microbes.
The treatment process involves placing contaminated water in direct contact with the bacteria. As the water flows through the basin, it is treated.
In this case, no perchlorate waste products are produced since the ions get entirely broken down.
Can Perchlorate Be Boiled Out of Water?
Perchlorates cannot be boiled out of water. Boiling may even increase the concentration of perchlorates in water.
What Is Perchlorate?
Perchlorate is a negatively charged ion consisting of a chlorine atom and four oxygen atoms. It can also refer to an inorganic compound containing the perchlorate anion and a positively charged ion like ammonium, alkalis/alkali earth metals, or other metal cations. Perchlorate esters and covalent perchlorate compounds also fall under the umbrella term “perchlorates”.
The Different Types of Perchlorate in Water
Perchlorate exists both naturally and artificially. The perchlorate ion is formed as a conjugate base from perchloric acid. Naturally, it is often found as covalent perchlorates or perchlorate esters (which are organic compounds formed as esters of perchloric acid).
However, commercially produced ionic perchlorates are more common in water. They include:
- Magnesium perchlorate (MgClO4)
- Sodium perchlorate (NaClO4)
- Potassium perchlorate (KClO4) and
- Ammonium perchlorate (NH4ClO4)
How Does Perchlorate Enter Our Drinking Water Supplies?
Perchlorate occurs naturally in the environment. High concentrations of perchlorate are found in the soils and groundwater in arid areas like the southwestern parts of the USA. Because of its highly soluble nature and mobility, perchlorate found in soil easily dissolves into surrounding water sources. And since it’s found in groundwater, it appears in drinking water extracted from aquifers.
Perchlorate is also present in commercial products like rocket propellants/missile fuel, automobile airbags, fertilizers, and fireworks. When these products are poorly disposed of (by the factories or consumers), they can enter our water supplies.
Contamination can also occur when runoff from natural deposits or fertilized lands enters the water supply. Atmospheric formation deposition in rainfall also happens in arid areas with high concentrations of perchlorates in natural deposits. A minor contributor to the presence of perchlorates in drinking water is the hypochlorite solutions used in treating water supplies.
How Much Perchlorate Can Be Found in US Water Sources?
Despite the alarm they seem to cause, the EPA has previously determined that perchlorates do not occur at levels of public health concern in water systems in the US.
However, exposure seems to be quite widespread. Perchlorate was identified at least once in 4% of the 3800+ community water systems sampled across the US. In 26 states and two territories, it was found that detectable levels of perchlorate in water averaged 9.8 µg/L. Minimum levels reported were 4 µg/L, while maximum levels reached 420 µg/L.
Drinking Water Standards
Since the EPA determined that perchlorates present in drinking water sources in the US are not at levels of public concern, it decided not to issue a national regulation. Hence there’s no standard for perchlorates in drinking water.
The most recent recommendation is that drinking water levels should be no more than 4 µg/L or 4 ppb. However, some states like California and Massachusetts have taken initiatives to set drinking water standards for perchlorate.
Health Effects
Exposure to high doses of perchlorate (either through drinking, inhalation, or ingestion) can lead to interference with iodide uptake by the thyroid gland. Consequently, the functions of the thyroid gland get disrupted, and the production of thyroid hormones is reduced. This leads to a disturbance in the metabolic processes the thyroid hormones regulate.
Perchlorate exposure is even more dangerous to pregnant women (fetuses) and infants. This is because thyroid hormones are critical for brain and nervous system development. As such, perchlorate exposure has been linked with an increased risk of neurodevelopmental impairment in fetuses. Also, it has been implicated in delayed development and reduced learning capability in infants and children of pregnant and lactating women affected.
How You Can Test for Perchlorate in Your Water
Perchlorate is highly soluble in water. It’s also colorless and odorless. The only way to determine if it’s in your drinking water is by conducting a test.
You can consult a laboratory approved by the EPA, which will give you instructions on collecting the sample they will test. Afterward, you can compare the test results to your state’s guidance or advisory level. However, if your state does not have an advisory level, you can use the Perchlorate Interim Health Advisory provided by the EPA as a basis of comparison.
If you have any thoughts about the question, does RO remove perchlorate, please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
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