Filtering nitrate from tap water: risks and approach

What is nitrate and how does it get into tap water?

Nitrate ends up in our drinking water in two ways. First, through nature itself: through the breakdown of organic material in the soil. Second, and increasingly the main cause, via artificial fertiliser and animal manure from agriculture. When it rains, excess nitrate washes from the soil into the groundwater. Because around two-thirds of Dutch drinking water is extracted from groundwater, this is directly relevant to the water quality in your kitchen.

Other sources of nitrate include leaking sewer pits, septic tanks and industrial wastewater. In urban areas, nitrate levels are generally lower than in agricultural regions such as Noord-Brabant, Limburg and parts of Drenthe and Overijssel, where intensive livestock farming and arable farming place a heavy burden on the soil.

Nitrate in Dutch tap water: what does the RIVM say?

On paper, Dutch tap water is safe: all water companies meet the statutory standard of a maximum of 50 milligrams of nitrate per litre, as laid down in the Waterleidingbesluit and the European Nitrates Directive. Yet the RIVM paints a worrying picture.

In concrete terms, this means: the water that comes out of your tap meets the standard, but the pressure on water sources is increasing. Vewin, the trade association for drinking water companies, emphasises that the quality of drinking water sources is structurally under pressure from too much nitrate. Without additional filtering at home, you drink tap water that does meet the European standard, but that was produced from raw water which, just above that limit, contained higher nitrate levels.

According to Milieu Centraal, climate change is an additional risk factor: more intense rainfall washes more nitrogen from agricultural land into the soil, further increasing the nitrate load on groundwater.

What are the health risks of nitrate in drinking water?

Nitrate itself is relatively low in toxicity. The risk lies in the conversion: in the digestive system, nitrate can be converted into nitrite, which reaches the bloodstream and reduces the oxygen-carrying capacity of red blood cells. This leads to a condition called methaemoglobinaemia.

Infants and babies

The most direct risk applies to infants under six months. In them, stomach acid production is low, which makes it easy for gut bacteria to convert nitrate into nitrite. This can cause so-called blue baby syndrome: the blood cannot transport enough oxygen, recognisable by a bluish discolouration of the skin. The WHO and RIVM advise against using tap water with a nitrate level above 50 mg/litre to prepare baby formula.

Long-term risks for adults

In adults, long-term elevated nitrate levels are associated with an increased risk of bowel cancer. Research published in the scientific journal Environmental Health shows an association between chronic exposure to nitrate and colorectal cancer. In addition, a link has been made with thyroid conditions and, in pregnant women, with certain pregnancy complications. The RIVM emphasises that the combined intake of nitrate via food and drinking water is higher than desirable for part of the population.

Why use a water filter against nitrate in tap water?

Many people are satisfied with the idea that Dutch tap water is "safe". But "meets the standard" is not the same as "as pure as possible". Anyone who is pregnant, has a baby, or simply wants certainty about the quality of their drinking water, consciously chooses an additional filtering step.

At PureFilter, we see that customers mainly choose extra certainty, even when they live in a region where water quality is normally good. They want to know that nitrate, but also pesticides, medicine residues and heavy metals, don't end up in their glass.

An NSF-certified inline water filter under the worktop offers that certainty. Unlike a filter jug, an inline system filters all the water at the tap itself, without any action from the user. Capacity: up to 15,000 litres per filter cartridge, which for 1 to 3 people corresponds to around 12 months of use and for 4 to 6 people to around 6 months.

Which water filter removes nitrate best?

Not every water filter removes nitrate equally effectively. Below is a comparison of the most common options. If you first want an overview of the types of water filters and how they work, take a look at our pillar page.

The comparison between PureFilter and Brita shows that a Brita jug barely removes nitrate: the activated carbon filter in a Brita focuses mainly on chlorine and limescale. For nitrate removal you need a filter with ion exchange or an NSF 53-certified filter mechanism.

Reverse osmosis removes nitrate most effectively, but also filters out all minerals. That means you end up drinking flat water without calcium, magnesium and potassium. PureFilter solves this with Swedish Mineral Rock technology: while contaminants are removed, the filter actively adds calcium, magnesium and potassium to the water. So you get water from the tap that is both pure and mineral-rich.

Buying advice: the best choice for your situation

Families with babies or pregnant women

For families with infants or pregnant women, additional filtering of nitrate is strongly recommended. An inline filter under the worktop offers continuous protection without you having to think each time about whether the water is filtered.

Residents of agricultural regions

Do you live in Noord-Brabant, Limburg, Drenthe or Overijssel? Then there's a greater chance that the groundwater in your region contains higher nitrate levels before it's treated. A home filter provides extra certainty on top of the water company's purification.

People who are health-conscious

Even if you're not at acute risk, filtering nitrate is a logical choice if you're conscious about nutrition and health. Combine that with the mineral addition of Swedish Mineral Rock, and you drink water every day that contributes to your calcium and magnesium needs.

The PureFilter Mineral+ water filter costs €149.00 and includes one filter cartridge good for 15,000 to 20,000 litres. A replacement filter is available from €65.00. Compared to buying bottled water, which costs an average of €30 to €40 per month for a family of four, a PureFilter filter pays for itself within a few months. Check out the full range of water filters for home to find the solution that suits your situation.

Frequently asked questions about nitrate in tap water

Conclusion: filtering nitrate from tap water pays off

Dutch tap water is safe, but the growing pressure on groundwater sources from agricultural nitrate makes additional home filtering increasingly relevant. Especially in agricultural regions and for families with infants or pregnant women, an NSF-certified filter is not an unnecessary luxury.

PureFilter Mineral+ offers a well-thought-out combination: it filters more than 100 contaminants including nitrate, and at the same time adds calcium, magnesium and potassium via Swedish Mineral Rock technology. Installation takes 5 to 10 minutes, replacement filters are available from €65.00, and the total cost per litre of filtered water is a fraction of bottled water.

Want to know how to install the filter or which variants are available? Visit the page about the best water filter or check the frequently asked questions.