Nitrate in Drinking Water

Concerned about nitrate in your tap water? Fortunately, nitrate poisoning is rare in the UK. However, those with private water supplies are at increased risk. Nitrate removal from drinking water is possible in several ways.

Before resorting to expensive treatments or bottled water the first step should be to test the nitrate level.

What is Nitrate?

Nitrate is a naturally occurring compound formed from nitrogen and oxygen atoms. It has the chemical formula NO₃^-. High levels of nitrate in drinking water can be dangerous to our health.

Nitrifying bacteria in the soil produce nitrates. It's estimated that lightning also produces 10,000 tons of nitrates each day!

All plants need nitrate to produce foliage, it's one of the main components of modern fertilizers. Nitrate fertilizers have been boosting the yield of our crops since the 1920s.

How Does Nitrate Get Into Drinking Water?

Nitrate fertilizer applied to our crops can run off the fields into surface water such as streams and rivers. Nitrates also seep down through the soil and rocks and can contaminate groundwater.

The UK drinking water standard requires the nitrate concentration to be less than 50 parts per million.

Drinking water extracted from rivers and bore-holes in agricultural areas often contain nitrates. Nitrate contamination is a common problem for private water supplies (water wells). A 2019 study by the Drinking Water Inspectorate found 7.5% of samples contained too much nitrate.

What Are The Health Risks of Nitrate?

Nitrate is relatively stable and unreactive, and as such its toxicity is low. The action of the bacteria in the mouth and the gut can convert nitrates into toxic nitrites.

Nitrite can reduce the ability of blood to carry oxygen. Nitrites are dangerous for infants and pregnant women. At high levels, they can cause blue baby syndrome (methemoglobinemia). Thankfully, cases of methemoglobinemia are extremely rare in the UK.

Nitrites can react with other substances to form chemicals that may cause cancer. The World Health Organization (WHO) has classified them as potential carcinogens.

Can I Test My Water for Nitrates?

Independent laboratory analysis of your water supply is simple and accurate.

Tests provided by The Water Professor can provide assurance to anyone concerned about nitrates. In our Agricultural Test we will analyse your sample for common agricultural contaminants such as nitrate and nitrite, as well as phosphate. For a more comprehensive analysis, our Standard Test will provide information on a number of toxic metals such as lead or arsenic, and water nutrients such as zinc and iron.

Removing Nitrates

You cannot remove nitrate by boiling your drinking water. Removing nitrate from water can be expensive so we recommend that you test your water first. There are three main methods for removing nitrates and improving your water quality:

• Distillation - Not particularly practical for most applications.
• Ion Exchange - Nitrate has a negative charge and is attracted to charged resins. Ion exchange has the disadvantage that it becomes less efficient with time.
• Reverse Osmosis - The most effective method of removing nitrate for most people. Reverse Osmosis (RO) uses special membranes to filter many contaminants from drinking water.

The bottom line

High nitrate levels in tap water pose a health risk but are rare in public water supplies. Bacteria in the body convert nitrates to nitrites which can pose a cancer risk. Nitrate removal can be expensive so we recommend testing your water first.