By Richard J. Lorenzen, CWS-II
Nitrate concentration in drinking water is a growing problem, especially here in Nebraska where 80 percent of public systems and virtually all private well systems are supplied by groundwater. Nitrogen is essential for all living things, as it’s a component of protein. Nitrogen exists in the environment in many forms and evolves as it moves through the nitrogen cycle.
Nitrogen is the predominant nutrient used for lawn and garden care and crop production. Feedlots, animal yards, septic systems, and other waste treatment systems are additional sources of nitrogen. Nitrogen occurs naturally in the soil in organic forms from decaying plant and animal residues, and will rarely exceed 3 milligrams per liter (mg/L) or parts per million (ppm). Bacteria in the soil convert various forms of nitrogen to nitrate, a nitrogen/oxygen ion (NO3-). This is desirable as the majority of the nitrogen used by plants is absorbed in the nitrate form; however, nitrate is highly leachable and readily moves with water through the soil profile. If there’s excessive rainfall or over-irrigation, nitrate will be leached below the plant’s root zone and may eventually reach groundwater.
Identifying the dangers
Excessive concentrations of nitrate in drinking water can be hazardous to health, especially for infants and pregnant women. Nitrate concentration is known to cause a condition called methemoglobinemia (or blue baby syndrome) in infants, which inhibits the blood’s ability to carry oxygen. The federal maximum contaminant level (MCL) for nitrate in drinking water is 10 mg/L.
A potential cancer risk from nitrate (and nitrite) in water and food has been reported. A possibility exists that nitrate can react with amines or amides in the body to form nitrosamine, which is known to cause cancer. Nitrate must be converted to nitrite before nitrosamine can be formed. The magnitude of the cancer risk from nitrate in drinking water is undetermined at this time.
Nitrate in water is undetectable without testing because it’s colorless, odorless and tasteless. A water test for nitrate is highly recommended for homes or acreages using a private well system with infants, pregnant women, nursing mothers or elderly people in the home. These groups are the most susceptible to nitrate. Public systems are required by law to regularly test for nitrates and any violations are to be reported immediately to all end users.
On-site testing can be performed with a field test kit to provide an indication and approximate level of nitrates; however, the results may not be as accurate as a laboratory test. Therefore, it’s recommended that a licensed approved laboratory analyze the water for more accurate results.
If excessive nitrate concentration is present in your water supply, you have two basic choices: obtain an alternate water supply or use some type of point-of-use (POU) or point-of-entry (POE) treatment system to remove the nitrate-nitrogen.
Nitrate can be removed or significantly reduced from drinking water by three methods: distillation, reverse osmosis (RO) and ion exchange.
The distillation process involves heating the water to boiling and collecting and condensing the steam by means of a metal cooling coil. Almost 100 percent of the nitrate can be removed with a properly manufactured and maintained distillation system.
Most RO systems force water under pressure through a series of prefilters, a semi-permeable membrane and finally a carbon postfilter. As the water passes through, the membrane filters out most of the impurities. According to manufacturers’ literature, from 85 to 95 percent of the nitrate can be removed with RO. Actual removal rates may vary, depending on the initial quality of the water and the system pressure. Water treatment dealers must be very careful when making statements regarding removal claims of an RO system.
Ion exchange for nitrate removal operates on the same principle as a household water softener. In a standard water softener, calcium and magnesium ions are exchanged for sodium ions. However, for the nitrate removal process, special anion exchange resins are used that exchange chloride ions for nitrate and sulfate ions in the water as it passes through the resin. In the past several years, a number of resin manufacturers have developed nitrate selective resins that have a greater tendency to remove or affinity for nitrates than sulfates in the water. Success can readily be achieved using nitrate selective resin in two ways. One is as a standalone unit with 100 percent of the mineral tank containing the selective resin. The other combines a regular water softener resin and the selective resin together in the mineral tank to offer a dual-use unit. Choosing a system type depends on the clients’ needs and the amount of nitrates and other contaminants in the water (hardness, iron, manganese, sulfates) to be removed.
It’s important to explain both the initial cost and the operating costs to potential or current clients. Operating costs include the energy needed to operate the system, additional water that may be needed for flushing the system, consumable supplies (such as regenerating salt) and filters, repairs, and general maintenance.
Reputable water conditioning equipment dealers can assist clients in evaluating available equipment. Consumers should be encouraged to look for someone that’s Water Quality Association (WQA) certified as a Certified Water Specialist (CWS) or Certified Installer (CI) and/or to check with their local Better Business Bureau for added assurance. As for manufacturers, you can encourage consumers to check with independent certifying agencies to see if a particular product is listed for a specific application. This helps assure the equipment will perform the necessary task, as well as maintenance and repair parts will be available when needed.
The WQA Gold Seal Program and NSF International both operate voluntary services to test water treatment equipment for manufacturers and post listed equipment on their websites. Equipment listed by WQA and NSF has been evaluated, meets the test standards requirements and normally has a label identifying the WQA or NSF testing. This independent testing provides some assurance that the manufacturers’ claims have been verified by a third party.
There’s a need for continued effort to work with the Department of Housing & Urban Development (HUD)—see “Update”—to see if we can rework the requirements to allow proven technology to be used and allow additional third parties to test to an accepted standard. This dialogue should include industry members as well as WQA staff. This needs to be a well organized effort possibly using a task force approach with members—including knowledgeable dealers, manufactururers and technical—appointed by WQA leadership . Meanwhile, customers should be assured there is equipment available on the market that can indeed drastically reduce many of the problems caused by excessive nitrate concentrations in drinking water.
About the author
Richard J. Lorenzen is vice president and operations director of Quality Water Services Inc. Lincoln, Neb. Lorenzen has been in the water treatment industry for 14 years and currently holds the WQA designation of Certified Water Specialist Level 2. He can be contacted at (402) 423-0909 or email: [email protected].
UPDATE: Nitrate, the legislative perspective & HUD
In spite of continued efforts to promote and pass meaningful and useful federal legislation to reduce roadblocks to applying point-of-use/point-of-entry (POU/POE) water treatment technology to nitrate removal, stonewalling still occurs at the bureaucratic level. This process was started during the mid-1980s, in an attempt to get our industry products accepted for POU and POE use. Nebraska Congressman Doug Bereuter has helped us lead the effort. Adequate legislation was successfully passed. This followed a lengthy process of public hearings throughout Nebraska to identify the nitrate problem and justify the need for legislative action.
Many of you will recall that prior to legislation, the only option to correct a water problem from nitrate or other contamination was to seek an alternate water supply. In many parts of the country, a viable water supply was most often simply not available. Because of that dilemma, many U.S. citizens were unable to refinance or sell their property. Unfortunately, Congress merely passes legislation while the responsibility of interpreting or crafting regulations from the legislation is left to the career bureaucrats. Such is the case with legislation that was passed to allow use of POU and POE industry products to ensure a continuous supply of water meeting quality requirements. Bureaucrats have continued to develop and regularly change regulations making it nearly impossible for product compliance.
At this time, we’re currently operating under Housing & Urban Development (HUD) mortgage letter 95-34. This letter gives specific procedures that a lender must follow to receive an FHA mortgage insurance certificate on properties that are served with an individual water well. This mortgage letter addresses the water test, water sampling and a reference to mortgage letter 92-18, which specifically addresses water purification systems. The 92-18 letter also specifically leaves the responsibility of assurance of water quality and performance up to the local health authority. Most states or local health authorities are very reluctant to take this responsibility for two very obvious reasons. First, most states and local health authorities are under severe budget restraints just trying to conform to current testing requirements on public supplies. To reach out and cover private water supplies goes beyond where most feel they want to venture. Second, state and local health authorities don’t see their role as selecting service providers to ensure a private well and equipment installed meet standards.
Mortgage letter 92-18 also provides strict guidelines in several areas regarding each of the following:
- Approval of the system by NSF;
- Certification by the State Department of Health;
- Notice to the homebuyer prior to the signing of the sales contract;
- Received—a written certification by the homebuyer acknowledging the water purification system, the unsafe nature of the water if not processed through that system, as well as other maintenance and disclosure issues;
- Service contract for servicing, maintenance of an escrow account for maintenance and replacement of the system;
- Establishment and maintenance of an escrow account for maintenance and replacement of the system;
- Approved plan in the form of a contract entered into by the mortgagor and mortgagee, and approved by the State Department of Health;
- Received—a copy of the State Department of Health letter confirming the aquifer contamination is filed with the VA Regional Office in the VA Loan Docket.
- Provide evidence that all of the requirements in HUD Mortgagee Letters 92-18 and 95-34, concerning individual residential water purification systems, have been met for this property.
These items are outlined in a standard letter sent out by the appropriate agency FHA or VA for homes on which they are the primary lender. They are referred to as minimum property requirements (MPRs) for any property not meeting the MCL standard of 10 mg/L of nitrate. In the letter, a request of a waiver may be made for any part(s) of HUD letter 92-18 if you cannot comply, stipulating:
- The reason(s) you cannot comply, and
- Documentation for the items with which you can comply.
The lender is then reminded it’s responsible to provide continued maintenance of the water treatment system and to ensure the system is providing acceptable water quality. The well water serving this property must be treated by the homeowner to consistently provide a nitrate level of less than 10 mg/L.
As I mentioned earlier in this article, we’ve been successfully treating nitrate water with RO and distillation primarily for a single tap POU application. In order to comply with the POU and POE and “every tap treated” concept, we’re successfully using ion exchange technology.
Our primary problem concerns the continued insistence of government to require only NSF-certified and third party tested equipment for nitrate reduction. Currently to my knowledge, neither WQA nor NSF have certified a POE product for effective use in nitrate removal.