Presence of arsenic in drinking water can be from the following sources:

  • natural geological formation
  • industrial discharges
  • agricultural run-off

Natural Geological Formation

Arsenic presents naturally in underground rocks and soils worldwide. It binds to rust particles (iron oxides) and stays in solid forms.

When there is no oxygen, iron-reducing bacteria that present in the soil will transform solid phase iron oxides Fe (III) to soluble iron Fe (II). Then it releases Arsenic that binds to it.

When the rocks and soils is in contact with underground water, the inorganic salts of arsenic dissolved and release into the underground water.

Two forms of arsenic are As(III) and As (V).

The dissolved arsenic salts can be transported from:

  • underground water to surface or
  • it will go deep to below 100 to 130 feet below the surface (aquifers).

This natural process of reaching the aquifer would take at least 100 years.

Industrial Discharges

Arsenic and arsenical compounds is used in the following industries:

  • metallurgical industry (zinc, lead or copper alloys)
  • glassware industry
  • ceramic industry

  • dye industry

  • petroleum refining industry

  • semiconductor industry

  • microchip production

  • wood preservatives

Argricultural Run-off

Arsenic is used in some of the insecticides and fungicides manufacturing. Insecticide and other pesticides are used in the farm and agricultural lands.

What is the health risk of having arsenic in drinking water?

Arsenic is tasteless and odourless. It is toxic and can cause cancer (carsinogen) and may act as co-carcinogen.

Table 1. Summary of various studies published in the scientific journal all around the world.

Type of RiskConcentration of Arsenic in Drinking WaterQuantity of Drinking Water ConsumedRiskSource
Death caused by various cancers:

Liver cancer, Lung cancer, Bladder cancer, Kidney cancer

50 ppb1 litre per day13 in 1000 personsEnvironmental Health Perspectives, 97, 259-267. (1992)
Bladder cancer, Lung cancer3 ppbDaily1 in 1000 personsArsenic in Drinking Water: 2001 Update. National Research Council
Blood Vessel Diseases:

Heart attack, Strokes, Atherosclerosis, Blackfoot disease

3 times the risk of atherosclerosis as people who were not exposed to arsenic.Science Daily (Mar. 28, 2002)
Neuro-sensory effect (nervous system)150 -170 ppbDailyReduce vibrotactile thresholdsJournal of Water Health, 04, 39-48. (2006)
Neuro-sensory effect (nervous system)400 ppbDailyReduce pain thresholdsJournal of Water Health, 04, 29-37.(2006)
Skin lesions50 ppbDailyJournal of Water Health, 03, 101-107. (2005)
IQ of girls100 ppbIQ decreasedJournal of Hygiene Research, 36 (3), 347-349. (2007)
Liver cancer in childrenIncrease in childhood mortalityCancer Epidemiology, Biomarkers & Prevention, 17 (8), 1982-1987. (2008)
Bronchiectasis (lung disease )Epidemiology, 16 (6), 760-765. (2005)
Circulatory system diseases,
Diabetes mellitus (type 2 diabetes),
Cerebro-vascular diseases,
Kidney diseases
Average 11 ppbElevated mortality ratesEnvironmental Health, 6, 4. (2007)

Notes:100 ppb = 100 [micro]g per litre = 0.10 mg per litre of drinking water

Table 2. Example of Contamination of Arsenic in Well and Underground Water

AreaConcentration of ArsenicSourceSummary of Survey
Tainan (Taiwan)600 –-2000 ppbJournal American Water Works Association, 65(9), 543-548. (1973)244 deaths due to blackfoot disease.
Cordoba (Argentina)900 –-3400 ppbBiological and Environmental Effects of Arsenic, B.A. Fowler (ed.), Elsevier Science Publishers, Amsterdam, 6, 199-232. (1983)165 deaths due to cancer of the respiratory system and gastrointestinal tract.
West Bengal (India)Above 50 ppbAnalyst, 120(3), 643-650, 917-924. (1995)175,000 people showing arsenical skin lesions.

Notes:100 ppb = 100 [micro]g per litre = 0.10 mg per litre of drinking water

So, what is the permitted level / guideline of arsenic allowed in drinking water?

  • United States Environment Protection Agency (US EPA) Standard 2006 – 10 ppb
  • National Sanitation Foundation (NSF) Standard – 10 ppb
  • World Health Organization’s (WHO) guideline 1993 – 10 ppb
  • Health Canada’s guideline 2006 – 10 ppb

  • European Union’s guidelines – 10 ppb

  • Australian Government National Health and Medical Research Council (NHMRC) guideline 2004 – 7 ppb

Notes: 10 ppb = 10 [micro]g per litre = 0.010 mg per litre of drinking water

However, the presence of arsenic in drinking water should be reduced to as close as possible to zero.

Why NSF certification is important for your drinking water filter?