Nitrate in drinking water: How dangerous is it?

We explain how nitrate is related to climate change, why the distinction between groundwater and drinking water is so important and what we can do to reduce nitrate pollution in water and soil.

Nitrate in water – you may have heard of it before. But where exactly can nitrate be found and when does it become a threat to our health? For many people in Germany, it seems obvious that we simply turn on the tap to get clean water. We regularly point out that in other parts of the world, 578 million people have no access to clean drinking water But who is aware that the drinking water supply in Germany is also at risk in the long term? Due to nitrate in the groundwater, cleaning is becoming increasingly complex. According to the Nitrate Report 2020 The nitrate content at 27% of the measuring points in Germany is above the critical threshold of 50 mg per litre. Recent studies show that drinking water could be contaminated due to the high nitrate levels. up to 62% more expensive if something does not change immediately. What needs to change? We need to ensure that less fertilizer is used on our fields! Because excess nitrogen ends up in the groundwater in the form of nitrate and makes drinking water treatment more difficult. Balancing water protection and agriculture is therefore also a key concern for water suppliers.

what is nitrate? effects on health and the environment

To put it very briefly: Nitrate is an elementary building block of nature - more precisely, a nitrogen compound. And nitrogen, in turn, is one of the macronutrients that plants most often need. To promote plant growth, the soil is fertilized with nitrogen.

• A distinction is made between elemental and reactive nitrogen. 99% of the nitrogen present is elemental nitrogen. It is found in the atmosphere.

• The remaining one percent is known as reactive nitrogen. Reactive nitrogen is converted into greenhouse gases that harm the climate through the influence of microorganisms in the soil. The microbial conversion of nitrogen-containing fertilizers in the soil, for example, produces nitrous oxide, which accelerates climate change.

• Another problem: Since fertilizers are often used in excess, a large part of the reactive nitrogen cannot be absorbed by the plants and becomes a burden on water and soil.

• More than 60% of reactive nitrogen compounds in Germany come from agriculture. All other nitrogen emissions originate from industry, traffic or private households. Due to industrialization and intensive agriculture, emissions from reactive nitrogen have increased tenfold since the mid-19th century and are now leading to significant environmental problems and health risks.

However, nitrate only becomes a threat to our health when it is converted to nitrite in food or during digestion. A distinction is made between Acute and long-term effects : There is an acute health risk for babies because their stomachs are still populated with bacteria that convert nitrate into nitrite more quickly than older children and adults. If nitrite gets into the blood of babies, oxygen uptake is reduced. In children and adults, too much nitrate intake in the long term leads to the nitrite formed reacting in the body to form N-nitrose compounds. These compounds have been proven to be carcinogenic in animals. No clear scientific results have yet been achieved regarding the long-term effects on the human body. However, one thing is clear: Too much nitrate in water poses a serious risk to people and the environment.

3 reasons why too much nitrate is a problem

1. Nitrate pollution in groundwater

Currently, 1,200 groundwater bodies in Germany are in a worrying state because the nitrate levels are above the threshold of 50 mg per litre set by the German Groundwater Ordinance. Groundwater in the catchment area of ​​agricultural land is particularly affected. In terms of the direct risk to health, it is important to distinguish between drinking and groundwater to distinguish: Even if the nitrate level in groundwater is often worryingly high, the quality of drinking water in Germany is very good and is strictly monitored. At 61%, more than half of our drinking water in Germany is obtained from groundwater, but this is cleaned at great expense before it flows out of the tap. Nitrate is filtered out during drinking water treatment using an electrochemical process. The more nitrate there is in the groundwater, the more complex and expensive the cleaning becomes. The water companies are therefore committed to ensuring that in the future it will not happen that large amounts of nitrate end up in the groundwater - through joint projects with farmers .

2. Nutrient oversupply and loss of biodiversity

An oversupply of nutrients occurs when more fertilizer is used than the plants need. The excess nutrients, such as nitrate, initially remain in the soil and are then washed into the surface water by rain. Too much nitrate in the water and soil upsets the natural processes and leads to excessive plant growth of species that can absorb particularly large amounts of nitrogen. In bodies of water, for example, an excess of nitrogen leads to increased algae growth, which is then accompanied by a general lack of oxygen in the water, so that species that depend on a high oxygen content in the water are displaced. Just as increased algae growth in water leads to the habitat becoming uninhabitable for other species, there are also land animal and plant species whose survival is threatened by an oversupply of nutrients such as nitrate. This is because nutrient-loving plants will reproduce particularly well in this state and the other species that have adapted to the nutrient-poor environment will be displaced.

3. Acceleration of global warming

The majority of people in Germany are now aware that CO₂ emissions are driving climate change and must therefore be reduced. What many do not know is that nitrous oxide is responsible for a disproportionately high proportion of global warming, as it 298 times more climate-impacting than CO₂ . 79% of nitrous oxide emissions in Germany come from agriculture. And not just from livestock farming, but directly from the fields. When microorganisms break down nitrogen-containing compounds such as nitrate in the soil, nitrous oxide is released into the atmosphere. This means that the more nitrate there is in the water and soil, the more nitrous oxide emissions are released into the atmosphere. Nitrate pollution therefore not only endangers the drinking water supply and biodiversity, but also contributes significantly to global warming.

what we can do to reduce nitrate pollution

An important prerequisite for reducing nitrate pollution is that farmers comply with fertilizer regulations. But each and every one of us also has opportunities to do something to improve the situation: through our consumer behavior, we can consciously support farmers who are committed to sustainable soil management. Since a particularly large amount of nitrogen escapes into the atmosphere during the production of animal products, a plant-based diet can also make an important contribution to reducing nitrate pollution and improving groundwater quality. And by the way: if you drink a lot of tap water, you ultimately also reduce nitrogen emissions from traffic and industry. This is because water that flows from the tap does not have to be packaged and always comes from sources in the region. When it comes to nitrate pollution in your own garden, you are of course in control yourself anyway. So: always use nitrogen-containing fertilizers in a targeted manner and in moderation. If we add exactly the amount of nitrogen to the soil that plants need to grow, nitrate will not be washed out and become a risk to people and the environment.