NITRATE IN DRINKING WATER: A HOLISTIC VIEW
NITRATE IN DRINKING WATER: A HOLISTIC VIEW
The debate about nitrate in drinking water has gained in importance in recent years. Because of the rising nitrate levels in some regions of Germany, water costs could even rise, warn experts and the Federal Environment Agency. With this article, we take a differentiated look at the topic of nitrate and provide information on the limit values and individual maximum amounts for different target groups, as well as ways to filter nitrate in drinking water.
Nitrate and health risks
Nitrates are salts of nitric acid (HNO3) and are soluble in water. They are used as mineral fertilizers in agriculture and thus enter our groundwater. Nitrate itself is not harmful to the human body. The problem arises when it is converted to nitrite in the body. Nitrite oxidizes the blood pigment hemoglobin to methemoglobin, which means that oxygen can no longer be properly delivered to the cell. This can lead to health problems, especially in infants. A recent study by the Water Quality Association in 2023 also found a correlation between high nitrate levels in water and certain diseases such as high blood pressure and certain types of cancer.
Limits and recommendation
The World Health Organization (WHO) has specified that 3.7 milligrams of nitrate per kilogram of body weight per day is permissible. Children over the age of three should not consume more than 93 milligrams per day.
The current limit value for nitrate in drinking water in Germany is 50 mg/l. However, some studies and experts argue that this value is set too high and recommend lower limits, especially for risk groups.
From the specifications of the groundwater ordinance, it can be seen that the federal government is aiming for a target value of 37.5 mg nitrate per liter. In the U.S., the Environmental Protection Agency (EPA) has set an enforceable standard, called the "maximum contaminant level" (MCL), of 10 mg/l for nitrates in water. The EPA assumes that a constant intake below this level should not cause significant health problems.
Limit values by groups as a guide:
General population: harmless up to 10 mg/l
Healthy adults: up to 37.5 mg/l harmless
Infants: harmless below 3 mg/l
Persons with colorectal cancer: up to 4 mg/l harmless
Infants: 0 mg/l
Filter nitrate in water
There are different methods to filter nitrate from water. Pure activated carbon filters, as we use them at LEOGANT, cannot influence the nitrate content in the water. So if you want to remove nitrate from the water, you have the following options:
Via an ion exchanger using a special resin:
This exchanges the nitrate ions from the water for sodium. This effectively reduces the nitrate content in the drinking water, but increases the sodium content in the water. The exchange ratio is 1:1, so if you want to remove 50 mg/l of nitrate, you artificially add 50 mg/l of sodium to the water. It should be noted that already from a value of 20 mg/l the water is no longer considered low in sodium. Therefore, this type of nitrate reduction is not recommended for risk groups. In addition, with these ion exchange resins, nitrates can be released back into the water in the event of overuse and there is a risk of poisoning.By means of filtration with a reverse osmosis:
This is one of the most effective methods of nitrate removal. The reverse osmosis system removes almost all substances from the water, including nitrate. The disadvantage is that valuable minerals and trace elements are also removed. We recommend the use of reverse osmosis systems for nitrate levels that are significantly above the 50 mg/l limit. If you decide to use a reverse osmosis system for filtration, we advise you to remineralize and revitalize the water after filtering, because water from a reverse osmosis system no longer has a biological quality and is more difficult for the metabolism to process. Demineralized water also no longer complies with drinking water regulations.
Nitrates in food
However, before worrying about nitrates in drinking water and resorting to more aggressive filtering methods because of high nitrate levels, it is important to check your own eating habits first.
People in Germany consume an average of around 90 milligrams of nitrate per day in their diet. By way of comparison, the daily limit for a person weighing 60 kilograms is 222 milligrams of nitrate - according to the WHO, which recommends a maximum of 3.7 milligrams of nitrate per kilogram of body weight per day. Thus, on average, adults do not exceed the limit values.
Therefore, the individual's own eating habits play an important role in determining the amount of nitrate consumed. The largest sources of nitrate intake are nitrite, meat and sausage products (nitrite curing salt) and vegetables. Fertilization is not the only factor that influences the nitrate content in vegetables. Some vegetable varieties store nitrates, while other varieties accumulate little with them. Leafy and root vegetables in particular, especially arugula and spinach, can have high nitrate concentrations of more than 1000 milligrams per kilogram. Fruiting vegetables such as tomatoes, peppers, cucumbers, beans or peas usually have a nitrate content of below 500 milligrams per kilogram.
Tips for reducing the nitrate content in foods
You can reduce the nitrate content in food by, among other things, blanching or cooking vegetables before eating them. This causes 40-80 percent of the nitrate to be lost. When preparing leafy vegetables, remove stems, stalks, large leaf veins and outer bracts. Light can also reduce nitrate levels in vegetables. Photosynthesis reduces nitrates in the plant and converts them to proteins. Therefore, higher light intensity and longer exposure times can cause plants to consume more nitrate. This process still takes place after harvesting.
Summary
So anyone who is concerned about the possible high nitrate levels in their drinking water must first and foremost review their eating habits. As long as sausage, meat and vegetables containing nitrate are still on the menu, even a limit value of 50 mg/l nitrate in drinking water is negligible. This is because 500 mg and more can easily be absorbed through the diet. If this were to be converted into water, one would have to drink 10 liters of water with the maximum permissible value of 50 mg/l. Moreover, a healthy adult need not immediately fear health effects if he or she ingests higher amounts of nitrates from time to time. It is only problematic if increased nitrate levels are regularly ingested via water and food.
In summary, a healthy adult need not be concerned up to a limit of 37.5 mg/l, provided the diet is low in nitrates. If one drinks a recommended amount of 2.5 liters daily, one would come to 93.75 mg sodium. This is only slightly above the daily maximum of 90 mg recommended by the WHO. For all other groups, our specified limits apply.
About the author:
Thomas Hartwig is a certified medical nutritionist and founder of the company Leogant. For many years he has been intensively involved with the element of water. He is a valued keynote speaker and guest on podcasts, where he shares his knowledge and experience. In his work he combines findings from natural science and medicine with philosophical approaches to contribute to a holistic water awareness.