Nitrates are a natural product that is naturally in the ground. Nitrate is a compound that is formed naturally when nitrogen combines with oxygen or ozone. All rainfall and groundwater aquifers contain some nitrate-nitrogen. Nitrate can occur naturally in surface and groundwater at a level that does not generally cause health problems. Contaminated rural water supplies come mostly from farmers. Nitrate accumulates in farmland watersheds where farmers spread fertilizers and animal manure on their crops. Nitrogen not taken up by crops can leach through the soil to groundwater and then flow to private wells. Residents that use septic systems and homeowners spray lawn fertilizers. These too can be sources of nitrate in drinking water.
High levels of nitrate in well water often result from improper well construction, well location, overuse of chemical fertilizers, or improper disposal of human and animal waste. Sources of nitrate that can enter your well include fertilizers, septic systems, animal feedlots, industrial waste, and food processing waste. Wells may be more vulnerable to such contamination after flooding, particularly if the wells are shallow, have been dug or bored, or have been submerged by floodwater for long periods of time.
Nitrogen is essential for all living things, but high levels of nitrate in drinking water can be dangerous to health, especially for infants and pregnant women. Nitrates are also made in large amounts by plants and animals and are released in smoke and industrial or automotive exhaust.
Home Water Treatment may be an option if you meet these three criteria:
You have taken steps to reduce or eliminate potential sources of nitrate on your property;
A licensed well contractor inspected your well and determined it is working properly; and
No babies under six months old drink the water (this is a safety precaution in the event the water treatment fails).
One of the most effective ways to eliminate nitrates is to use an ion-exchange process. Ion exchange is a traditional method used by traditional water softeners, but this method can be used to eliminate contaminants other than just water hardness 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 will 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 rather than positively charged cations).
These ion-exchange nitrate filters will have a rated gallon capacity lifespan. They will only be capable of processing a certain volume of water before all the chloride ions are exhausted and 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. This is another reason why thoroughly understand your water’s composition is of great importance. It is also very important to 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 a brine solution. This brine 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.
Standard anion resins. The two types of standard resins commonly used for nitrate removal today are Type 1 and Type 2 strongly basic anion exchange resins. The Type 1 resin derives its ion exchange capabilities from the trimethylamine group. The Type 2 resin derives its functionality from the dimethylethanolamine group. The relative order of affinity for the three most common ions in drinking water compared to nitrates is
Sulfate > Nitrate > Chloride > Bicarbonate
Nitrates may be successfully removed from water using treatment processes such as ion exchange, distillation, and reverse osmosis.
Heating or boiling your water will not remove nitrate. Because some of the water will evaporate during the boiling process, the nitrate levels of water can actually increase slightly in concentration if the water is boiled. Mechanical filters or chemical disinfection, such as chlorination, DO NOT remove nitrate from water.