Nitrates are compounds that occur naturally within the earth but are found in elevated levels in agricultural communities and rural towns. Because they can pollute water supplies in various ways, nitrates are one of the most common contaminants well owners are faced with eliminating from their water supply. While they do not present any taste or odor, drinking elevated levels of nitrates can cause illness in both humans and livestock. Fortunately, multiple water treatment processes can eliminate the threat of nitrates from home water supplies. In this article, you can learn what nitrates are, how to remove them from water, and answers to common questions surrounding nitrates in water.
What are nitrates in water?
Nitrates are inorganic compounds made up of nitrogen and oxygen that occur both naturally and synthetically in the environment. They are easily biodegradable and highly soluble in water and can be found in the atmosphere, in soil, and in water. Nitrates are created by plant decomposition, animal waste, and as an agricultural byproduct. Rainwater, floods, and soil erosion can all lead to nitrates being introduced to groundwater supplies.
Nitrogen is one of the most essential nutrients for prosperous plant and crop growth. Nitrogen is one of the building blocks of the chlorophyll molecule, which allows plants to create food for themselves through the process of photosynthesis. Fertilizers for lawns, gardens, flowers, and crops all use nitrates to provide the plants with this natural energy to help the plants flourish and remain healthy. When these fertilizers are carried by floods or rainfall into streams and lakes, nitrate levels in the groundwater will escalate.
Nitrogen is abundant in our environment and critical to the health and growth of all living creatures. However, excessive consumption of nitrogen compounds can lead to health complications and illness.
How do nitrates get into water?
Nitrates enter the water supply through agricultural run-off, industrial waste, the use of fertilizers and herbicides, and from leaking septic tanks and burst sewage systems. Naturally occurring bacteria found in soil can also metabolize nitrogen into nitrate deposits in the earth. Rainwater can carry manure from farmlands into streams and lakes. Animal waste is another common way for nitrates to be introduced into water supplies. Crop irrigation can embed nitrates deep into the soil, and they can find their way to aquifers as precipitation percolates down through the earth. As natural deposits of nitrates erode, increased concentrations can appear in underground water systems being used for well water.
Where are nitrates found?
Nitrates are most commonly found in rural, agricultural communities that depend on well water. Since there are clear EPA regulations for nitrate levels in municipal water supplies, it would be very uncommon to find elevated nitrate levels in city water. In farming communities where fertilizer, pesticides, and animal waste are common, it is not unusual to find undesirable levels of nitrates in water. Livestock facilities also generate nitrates, as the waste produced by the animals can make its way into groundwater aquifers. Since many of these rural communities rely on wells to provide their homes with drinking water, the contamination of these water supplies is especially problematic. These wells, if bored into a shallow aquifer downstream from farmlands, are very likely to be contaminated with elevated nitrate levels. Agricultural watersheds are the most likely to suffer from undesirable levels of nitrates in water.
Those living within the vicinity of industrial manufacturers may also find their wells contaminated with nitrates. Nitrates are commonly used as oxidizing agents in the production of ceramics, to remove air bubbles from glass, and as an agent to harden metals. Nitrates are also used in munitions and explosives manufacturing. High nitrate levels also occur around golf courses, near wastewater disposal sites, and landfills.
Are nitrates in water harmful?
Drinking water with high levels of nitrates has been associated with health risks, specifically for infants. According to a report published by the Minnesota Department of Health, elevated levels of nitrates decrease red blood cells’ ability to transport oxygen around the body. This deprivation of oxygen is most serious for small children, who can develop a condition called methemoglobinemia. Red blood cells contain an iron-based compound called hemoglobin, which is responsible for carrying oxygen. When infants consume nitrates, they transition into nitrites in the child’s bloodstream. When nitrite is present, this hemoglobin is converted to methemoglobin, a compound that is incapable of transporting oxygen. While adults have enzymes that defend nitrites from attacking their bloodstream, infants, unborn babies, and the elderly do not have this security measure in place. Adults also have more bodyweight and larger circulatory systems, putting them at less risk than infants under six months.
Methemoglobinemia, also known as “blue baby syndrome” is the most common health concern associated with nitrates. A child with blue baby syndrome will start displaying bluish or brownish colors around their lips and mouth, nose, and nail beds. It can also present flu-like symptoms, such as nausea, vomiting, and diarrhea. If you believe your child is suffering from blue baby syndrome, you should seek professional help immediately.
Do nitrates affect adults?
While there is some information that implies nitrates and nitrites may be linked to illness (like gastrointestinal complications, increased heart rate, headache, and nausea) in adults, there is no scientific consensus on this yet. Nitrates are primarily understood to be risks for children and the elderly. They can also exacerbate medical conditions in adults with low stomach acid or with an inherited lack of a specific enzyme (methemoglobin reductase). The World Health Organization (WHO) determined that nitrates were probably carcinogenic to humans, although it is unlikely that drinking water with nitrates alone would be enough to cause cancer. Ultimately, the epidemiologic data on the dangers of long-term consumption of nitrates remains inconclusive.
How much nitrate is safe in drinking water?
According to the EPA, drinking water should contain no more than 10 ppm of nitrate, and water with less than 10 ppm of nitrate is considered safe to drink. You may also see this measurement as 10 mg/L. Nitrates are considered a primary water quality contaminant, meaning the contaminant levels are enforced by regulations. The EPA sets maximum contaminant levels (MCLs) for these contaminants, as drinking water with elevated levels could potentially lead to health complications and illness. Other contaminants regulated by the EPA’s primary standards include lead, arsenic, asbestos, and bacteria like giardia and cryptosporidium.
How to test for nitrates in water
The best way to test for nitrates in your well water is to submit a water test kit to a certified laboratory. These comprehensive water tests evaluate the levels of 75 different water contaminants and provide you with a thorough, detailed assessment of your well’s water quality. If you own a private well, it is imperative that you regularly monitor your water quality. Nitrates are tasteless, colorless, and odorless, so the only way to determine their presence is through testing.
To perform the water test, you will gather multiple samples of your well water and store them securely in provided vials. These will then be sent to the lab, and the water will be subject to the rigorous tests to determine the chemistry of your water. Each contaminant’s presence is measured, and the results are returned to you. These meticulous test results will notify you of every instance where the contaminants present in your water exceed the EPA’s regulatory standards for safe drinking water.
If you have already completed a full water test and have installed water filtration systems to reduce the nitrate levels in your water, you can periodically examine the water’s nitrate levels using test strips. These strips use a color gradient to give you a generalized idea of your water’s nitrate and nitrite levels, and they allow you to monitor your water and gauge the performance of your filtration systems.
How to remove nitrates from water
Nitrates can be removed from water by reverse osmosis, distillation, or through ion exchange resin. Nitrates are difficult contaminants to eliminate from water. They will not be removed by sediment filters, carbon filters, or by the hollow fiber membrane of an ultrafiltration system. Similarly, a traditional ion exchange water softener will not reduce or remove nitrates. If you want to remove nitrates for the entirety of your home, installing an anion resin tank at the point of entry is the most common and effective solution. If you wish to eliminate nitrates from only your drinking and cooking water, installing an under-sink reverse osmosis system is the recommended choice. You can also use a water distiller to eliminate nitrates from small batches of water at a time.
Reverse osmosis
Reverse osmosis (RO) removes contaminants by forcing pressurized water through a semi-permeable membrane covered in microscopic pores. These pores act like a sieve, separating the pure hydrogen and oxygen from the water’s contaminants. The membrane has such a fine micron rating that it can rid the water of ions like nitrates. The clean, treated water passes through the membrane and collects in a storage tank. The remaining contaminants are rejected by the membrane and flushed down the drain in a brine solution. Able to reduce over 98% of waterborne contaminants, reverse osmosis is one of the most powerful methods of residential water filtration. Reverse osmosis can remove anywhere from 83-92% of nitrates.
Reverse osmosis is popularly used to purify water used for drinking, cooking, and ice-making. RO systems are somewhat complex, requiring several stages of pre-filtration, storage tanks, and sometimes a pressure booster pump to increase feed line pressure. This makes them generally impractical for whole house water filtration with the exception of dire circumstances. If you are only interested in eliminating the nitrates from the water you and your family consume, RO is a strong choice.
Keep in mind that reverse osmosis does not remove all traces of nitrates, but rather greatly reduces the nitrate levels present in your water. If your well water has 30 ppm of nitrates, an RO system would be able to reduce the levels to somewhere between 3.5-2.5 ppm. This level is well within the EPA’s safe and acceptable range of nitrates. However, if you have extremely problematic water with around 100 ppm of nitrates, your water would likely have anywhere from 15-10 mg/L remaining after RO treatment. The higher the incoming nitrate concentration is, the less effective reverse osmosis will be at making the water safe for consumption. This is why performing a detailed water test is so important when choosing a water filtration system. In the case of such extreme levels of nitrates, a whole-house reverse osmosis system may be a plausible filtration system.
You should also note that reverse osmosis wastes water in the treatment process. While older RO systems send as much as 90% of the water they treat to the drain, advancements in technology and design have greatly improved the efficiency of RO. If you are concerned about conserving water, install a system with a permeate pump to recover the maximum amount of reject water. Reverse osmosis also suffers in homes with poor water pressure. The incoming water pressure needs to be forceful enough to propel the water through the membrane. If you have low water pressure, add an RO booster pump before your system to increase the contaminant reduction and efficiency of the unit.
Learn more: How reverse osmosis works | Do I need a whole-house reverse osmosis system?
Ion exchange
One of the most effective ways to eliminate nitrates is to pass the water through an ion exchange process. Ion exchange is most commonly found in traditional water softeners, but the method can be used to eliminate contaminants other than just water-hardening minerals. Water softeners use a brine solution to regenerate resin beads with sodium ions. When the hard water flows through the resin bed, the calcium and magnesium ions exchange for sodium ions and the water exits the tank softened.
Nitrate removal by ion exchange works on the same principle. Instead of sodium, these water filtration systems use chloride ions. When the contaminated water passes through the tank or cartridge, the resin beads collect the nitrate ions and displace the harmless chloride ions into the water in their place. This is known as anion exchange because both chloride and nitrate carry a negative charge, making them anions.
These ion exchange nitrate filters have a rated gallon capacity lifespan. They are only capable of processing a certain volume of water before all the chloride ions are exhausted. At this point, the media will either need to be regenerated or the cartridge replaced. The higher the concentration of nitrates in your water, the quicker the media will become exhausted. Nitrate-selective ion exchange systems can be installed as regenerative tanks filled with resin at the point of entry to the home, similar to a water softener. They also come in cartridge form, which can treat the entirety of the water in the house or selective treat water flowing to sinks and refrigerators.
For the ion exchange process to effectively eliminate nitrates from your water, your well water must not have elevated levels of sulfates. The ion exchange resin will attract both nitrates and sulfates, though it will preferentially select sulfates. If there are more sulfates than nitrates present in your water, the media will cease being effective at nitrate reduction. You should also consider the placement of your resin tank’s drain line. If you are using a backwashing tank system, it will periodically need to flush the system with sodium chloride to regenerate the resin and flush out the brine solution. This solution will be loaded with nitrates, so make sure it drains to a location far from your well or where any animal could access it.
Learn more: How to install a whole-house water filter for well water | How ion exchange water softeners work
Water distillers
The third way to eliminate nitrates from water is by the process of water distillation. Water distillers eliminate virtually all waterborne contaminants by emulating Earth’s natural filtration process known as the hydrologic cycle. In the hydrologic cycle, water evaporates from surface waters like oceans, lakes, and reservoirs. During the evaporation process, any impurities within the water droplets dissipate as the molecules convert from a liquid form to vapor. This includes salts, bacteria, sediment, and contaminants like nitrates. The gas then condenses while in the sky. It returns to the earth in a liquid state through precipitation like rain and snow in the form of slightly acidic soft water.
Water distillers work like a scaled down version of the hydrologic cycle. Water is placed into a chamber with a heating element that will boil the water until it has been entirely converted to steam. This steam then enters into a cooling coil. Here, the water is chilled until it returns to its liquid state. The water is then collected in a jug made of glass or plastic. When the water’s matter transitions between a liquid and gas, all water contaminants are left behind in the boiling chamber. Contaminants that can convert into a gas (like VOCs) are removed by the distiller's carbon post-filter. No nitrates can survive the distillation process.
As powerful as water distillation is, it is one of the slowest and most expensive methods of water purification. Most household water distillers take around 4 hours to distill a single gallon of water. If you have potentially dangerous levels of nitrate present in your drinking water, this is a very long wait for potable water. Furthermore, water distillers use significantly more water than other treatment systems. During those six hours of distillation, energy is consumed by the distiller to heat up the boiling chamber and chill the coils.
There are larger, industrial-sized water distillers available. These can hold as much as 12 gallons of distilled water at a time and produce it much quicker. These systems are equipped to distill water as quickly as 2-3 gallons per hour. These can even be plumbed to connect to a faucet or refrigerator so that you can access distilled water at a tap. However, these are far more costly than alternatives like reverse osmosis. Though they do not waste water, they do consume a great amount of electricity. For many, it comes down to a matter of preference between RO water and distilled water. Despite its drawbacks, distillation is a surefire way to ensure the water you and your family consume is free of any trace of nitrates.
Learn more: How water distillers work | What is distilled water and is it safe to drink?
Does boiling water remove nitrates?
No, boiling water does not remove nitrates. In fact, doing so increases the concentration of nitrates in your water. As the water boils, some of the water evaporates. leaving you with a more concentrated level of nitrates in the remaining water.
Note that distillation is a much more involved process than merely boiling water. The water is boiled until it has completely left its liquid state and converted into gas. This water vapor is chilled and returned to liquid form, free from nitrates and other contaminants. While boiling water is enough to neutralize harmful microorganisms and reduce chlorine content, it does not eliminate nitrates.
How to prevent nitrates from contaminating water
There are a few ways to mitigate the presence of nitrates in your well water.
- Construct your well away from contaminated sources. Shallow wells are much more likely to present elevated nitrate levels. The deeper the aquifer you draw from, the better the chances of you avoiding the runoff from the agricultural waste. If your well is located downstream from heavy irrigation or farmlands, consider relocating the well to a more secure spot.
- Have your well inspected. Call a licensed well contractor and have them perform routine maintenance and inspection on your well. If your well is damaged or underperforming, the water could be exposed to an increased level of contamination from nitrates and other waterborne invaders.
- Avoid using fertilizers and pesticides near the well. If your well is located on property that is being used for agriculture, be mindful of how manure, herbicides and pesticides, and fertilizers could be contaminating the water. Where possible, avoid using these products near your well or water sources that could transport nitrates into the aquifer you rely on for drinking water.
- Regularly test your well water. You should test your well water once each year to monitor the contaminants present in your water. You should also test your water at the beginning and at the six-month period of each pregnancy. To ensure that you water filtration systems are performing well, test water from your tap to ensure that nitrates, arsenic, and bacteria are not making their way into your home.
If you have any additional questions, please do not hesitate to contact us.