What are Nitrates in tap water and how can I filter or remove them?
Worried about nitrates in tap water? Nitrate is a compound that is formed naturally when nitrogen combines with oxygen or ozone. Nitrates therefore naturally ends up in both surface and ground water.
In this article we will talk about the source of nitrates, where they can be found, nitrates in drinking water, how dangerous they are and how to filter nitrates from your drinking water.
Where do nitrates come from?
Nitrate as a chemical is used mainly in inorganic fertilizers which is why it's common that people believe that agriculture run-off is the source of all nitrates in drinking water.
Most commonly nitrates are found in areas where significant plant decay underground. Nitrates are created as a part of the decaying process. They are very soluble and can move easily through soil. Therefore many vegetables are naturally high in nitrate and nitrite and constitute the main source for humans.
The other major source of Nitrates comes from animal waste run-off, excessive use of fertilizers, or seepage of human sewage from private septic systems. These nitrates are definitely unwanted in your tap water.
The increasing use of artificial fertilizers, the disposal of wastes (particularly from animal farming) and changes in land use are the main factors responsible for the progressive increase in nitrate levels in groundwater supplies over the last 20 years. In Germany there has been increasing awareness of this in the last couple of years causing people to worry about nitrates in the tap water.
Where does Nitrate come from in drinking water?
Nitrate can occur naturally in surface and groundwater at a level that does not generally cause health problems. Water treatment plants therefore monitor the nitrate content in the source water and treat it if required. Therefore the risk of high levels of nitrates in public tap water is low.
Private wells on the other hand is a much bigger challenge. Sources of nitrate that can enter your well include fertilizers, septic systems, animal feedlots, industrial waste, and food processing waste. 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.
Does my tap water contain Nitrates?
The best way to check is to ask your water supplier for a water quality report or if you live in Spain check out our water quality database. If you don't trust them an alternative is to buy test stripes online and check the water yourself. Buying a test-strip kit will give you a quick approximation in minutes. Above, a picture of the Nitrate reduction before and after TAPP Smart water filter.
In Europe (and most of the world except the US) the maximum allowed concentration is 50 ppm (parts per million) or 50 mg/l. This has been established by the WHO collaboration with water authorities in Europe, US, Australia, Japan and many other countries. The maximum limit is based on the risk assessment for infants and pregnant women. Find the full nitrate in drinking water report from 2011 here.
The US EPA limit for nitrate in drinking water is much lower at 10 ppm or 10 mg/L. This was set in 1962 due to a scare at the time of blue baby syndrome. The limit has been reviewed several times since then but never changed. Some public organisations like EWG claim that the limit should be even lower.
It’s possible that unlikely that you will find levels above the allowed maximum. According to official reporting all of the large utility companies in the US reported nitrate levels below the legal limit of 10ppm 2019.
How dangerous are Nitrates?
First of all most of your nitrate exposure comes from vegetables, fruits and cured meat. The exposure from tap water in relative terms is low.
Having said this nitrates in tap water could pose a health risk at higher concentrations although it's primarily to infants and pregnant women.
The guideline value for nitrate of 50 mg/l as nitrate is based on epidemiological evidence for methaemoglobinaemia in infants, which results from short-term exposure
and is protective for bottle-fed infants and, consequently, other population groups.
Below is a table provided by the Oregon Health Authority. As explained earlier, the legal limit varies depending on the country and region. What is for sure is that babies and pregnant women should not be exposed to levels above 50 ppm and preferably not 10 ppm.
What is the best water filter for Nitrates in tap water?
Depending on your level of Nitrates, you might want to reduce them. Carbon Block filters such as TAPP, will reduce about 70-80% of Nitrates in tap water (see test results). Compared to other more bulky and expensive alternatives such as Ion Exchange or Reverse Osmosis, carbon block faucet mounted filters provide an easy to install solution to reduce Nitrates well below the legal limit.
For wells with high nitrate concentrations a Reverse Osmosis or Ion Exchange filter is generally required.
Read more about how TAPP 2 works and removes nitrates from tap water.