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Groundwater nitrate and why it should concern us

  • Groundwater nitrate and why it should concern us

What do grazing cattle, usage of fertilizers and poor sanitation have in common?

Well, these activities affect our drinking water in more ways than we could imagine.


This valuable resource of drinking water has hydrated us for ages.

Though hardness might be an issue in a few places, groundwater has that epic taste that it delivers to our mouths.

However, the safety of groundwater in some areas is being compromised by a very unlikely pollutant.

High nitrate content

Not only is nitrate found in human waste, manure and fertilizer, most nitrate salts are highly soluble in water.

So what does this mean?

Simply put, nitrates easily percolate through the soil into our groundwater through a process called ‘leaching‘.

So activities that introduce nitrates to the surface such as fertilizer use, manure dumping and poor sanitation are significant.

But the problem doesn’t just exist on the surface.

Latrines constructed too close to wells and boreholes not only expose the water users to pathogens but high nitrate levels in water.

So what is the problem with high nitrate content in water?


Well first, both the Kenya Bureau of Standards (KeBS) and the United States Environmental Protection Agency (USEPA) recommend a maximum allowable nitrate level in drinking water of 10 mg/l.

Ingestion of water with concentrations above that could predispose children to a condition called the ‘blue baby syndrome‘ which could lead to death.

‘Blue baby syndrome’ happens when nitrate displaces oxygen by binding strongly to hemoglobin thereby suffocating toddlers.

But long term ingestion of water with a high nitrate content is associated with cancer development.

This is because nitrates are metabolized into N-nitroso compounds which are known tumor initiators.

Monitoring of nitrate movement in our environmental systems is still not taken as seriously as it should.

A check into publications about nitrate levels in groundwater resources in Kenya shows that there is more work to be done.

Nitrate levels in water is an analysis that is usually left to the back-banner with most researchers focusing on metals and other organic pollutants.

Another reason why nitrates matter is because they are a major source of nutrition for crops.

Nitrates lost through our water systems could be recovered and rechanelled back to agriculture.

This way, three problems could be solved:

  1. Nitrate pollution of our groundwater
  2. Loss of a crop nutrient
  3. Destruction of our environment due to eutrophication

Several strategies are key in this regard.

Conservation agriculture

Unnecessary addition of nitrates through fertilizers could be curbed through the use of plant residue.

For example, after harvesting maize, the stalks (which contain a significant amount of nutrients such as nitrates) could be left on the ground to shed off nutrients back into the soil.

These nutrients will be assimilated with organic matter further enriching the soil.

Controlled release fertilizers

Whereas conventional fertilizers release most of their nutrients almost immediately, controlled release fertilizers do so slowly and over time.

They ‘hold onto’ the nutrients while releasing only what’s necessary to spur growth.

They could help in preventing leaching of soluble salts such as nitrates into our groundwater.

Planned sanitation

Location of latrines in resource strained regions could help curb seepage of nitrates into groundwater.

Legislation to set minimum distance between latrines and boreholes is necessary in densely populated areas.


This age old practice of allowing organic matter to decay and convert into soil fertility is very useful in availing nutrients in a usable form.

Nitrate-rich materials could be mixed with carbon-rich material and allowed to decompose over time before being applied on farming soils.


Nitrate contamination of our water is an issue of concern especially in areas which are densely populated, practice livestock farming or use fertilizers are agricultural inputs.

Nitrates must be concentrated where they belong: in the farm.

This way, we could help prevent health issues that arise due to long term exposure to water with a high nitrate content.

Originally posted on John Mmbaga's Blog

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