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Acceptable Levels of Strontium and Silica in Drinking Water ? Comments invited!

I wish to consult the forum regarding the presence & acceptable levels of Strontium and Silica. The norms/standards for drinking water contained in IS 10500 (Bureau of Indian Standards)  do not prescribe any permissible or derired limit for these two elements.  Some pockets in Andhra Pradesh and Punjab reported presence of silica upto 150 ppm and strontium upto 3500 ppb. Can any of the esteemed experts, participating in the discussion here on the portal, comment on this please?

Information regarding the acceptable levels, applicable regulation & any related comments would be helpful.

Dr D R Prasada Raju



1. Max permissible levels of Silica & Strontium in drinking water

There are no specified levels for Silica and Strontium any where that I know of . The WHO, Canadian Govt's and U.S Govt's standards for drinking water do not specify any limits for these constituents, and I consider these among the most comprehensive standards today.I think research on the effects of these two constituents needs to be done before any meaningful limits can be specified.



2. EPA has set a limit of 4000

EPA has set a limit of 4000 micrograms strontium per liter of drinking water (4000 µg/L).

EPA has set a limit of 8 picocurie 90Sr per liter of drinking water.

The Nuclear Regulatory Commission has set limits for radioactive strontium in workplace air for a 40-hour work week of 6x10-8 microcurie per milliliter (µCi/mL) for 89Sr and 8x10-9 µCi/mL for 90Sr. EPA has set an average annual drinking water limit of 20 picocuries per liter (pCi/L) for 89Sr and 8 pCi/L for 90Sr so the public radiation dose will not exceed 4 millirem.

3. Plaese refer the link

Please refer the link below


Bharat Lodha,


Battelle Science & Technology India Pvt. Ltd.

4. Acceptable Levels of Strontium & Silica.

Dear Sir,

Strontium is the one of the most hazardous of all fission products.It decays very slowly with a half-life of 28 years.If it is ingested, it is concentrated in bones.No limits has been fixed for Strontium, but as it is Radioactive Material, the Maximum limits for Alpha Emitters is 0.1 Bq/l and Beta Emitters is 1.0Bq/l.The limits for Silica are also not fixed by any agency.As the water pollution is on rise and the presence of these constituents are being reported in some pockets, the limits should be fixed after proper observations.


Amit Kr. Singh,
Govt. of Haryana,
Public Health Engg. Department,
Water Testing Lab,Karnal-132001(haryana)

5. Standards for Strontium & Silica in Drinking Water

Dear Dr. Prasada Raju,

As for as I know, there appears to be no standards for Strontium and Silica in drinking water.

Neither of these are listed in primary or secondary contaminants of US EPA (see attached file) and are not mentioned in European drinking water standards. However it is included in contaminant candidate list 3. CCL 3 is a list of contaminants that are currently not subject to any proposed or promulgated national primary drinking water regulations, that are known or anticipated to occur in public water systems, and which may require regulation under the Safe Drinking Water Act (SDWA). The list includes, among others, pesticides, disinfection byproducts, chemicals used in commerce, waterborne pathogens, pharmaceuticals, and biological toxins. The Agency considered the best available data and information on health effects and occurrence to evaluate thousands of unregulated contaminants. EPA used a multi-step process to select 116 candidates for the final CCL 3. The final CCL 3 includes 104 chemicals or chemical groups and 12 microbiological contaminants.

Under this, US EPA has set a limit (not regulated) of 4000 micrograms strontium per liter of drinking water (4000 µg/L).

EPA has set a limit of 8 picocurie 90Sr per liter of drinking water.

To access click here: EPA Standards
The Nuclear Regulatory Commission has set limits for radioactive strontium in workplace air for a 40-hour work week of 6x10-8 microcurie per milliliter (µCi/mL for 89Sr and 8x10-9 µCi/mL for 90Sr. EPA has set an average annual drinking water limit of 20 picocuries per liter (pCi/L) for 89Sr and 8 pCi/L for 90Sr. So the public radiation dose will not exceed 4 millirem.

You can get more information from the following website:

As Strontium is in the same family as calcium and magnesium, it can be removed by softening methods, ion exchange resins as well as RO. But in the form of Strontium sulfate, it is a membrane foulant and thus reduces membrane life in RO.


Leela Iyengar

6. Standards for Strontium & Silica in Drinking Water

Dear Dr. Raju,

Perhaps there are no agreed permissible limits of above mentioned contaminants, at least I do not know.

However, I have searched the web and have attached some findings which may help you.
Strontium= 20000 ppb
Silica in the form of silicon = 28 ppm

These are only findings from the web. I do not have any experience on those contaminants.
With regards,

Diponkar Bordoloi
Assistant Engineer
Public Health and Engineering Department (PHED)
Guwahati, Assam

Click here to Download: Health based Limits for Strontium, Silica Levels

7. Acceptable Levels of Strontium and Silica in Drinking Water

Dear Dr. Prasada Raju,

The permissible or desired limits of strontium (Sr) and silica (SiO2) in drinking water have not been prescribed not only by the Bureau of Indian Standards (BIS) but also by similar agencies in other countries and the World Health Organization (WHO). The only exception is with the U.S. Environmental Protection Agency (EPA), which recommends for a limit of 4 mg/L Sr in drinking water. 

The levels of dissolved constituents in natural waters depend on their abundance in the Earth’s crust and their solubility in water. With a concentration of 370 ppm by weight in the Earth’s crust, strontium ranks sixteenth in abundance, while its moderate solubility makes seawater to contain 8 milligrams/litre (mg/L) of Sr mostly in divalent state.

Natural Sr is non-radioactive. The human body contains approximately 4.6-ppm strontium and its specific function has not been established. It is absorbed simply because of its similarity to calcium and gets concentrated in bones and teeth. Ingestion of food and water with high strontium particularly in children causes problems with growing bone. Consumption of food and water containing high calcium overcomes the problem.

Radioactive Sr-90, like many other radionuclides, was discovered in the 1940s in nuclear experiments connected to the development of the atomic bomb. It is a by-product of the fission of uranium and plutonium in nuclear reactors, and in nuclear weapons and is found in waste from nuclear reactors. Large amounts of Sr-90 were produced during atmospheric nuclear weapons tests conducted in the 1950s and 1960s and dispersed worldwide. The accident at the Chernobyl nuclear power plant has deposited Sr-90 mostly in the Soviet Republics, subordinately in Northern Europe and very little in other parts of the world.

The risk of radioactive strontium intake is mainly based on its carcinogenic and mutagenic mechanism, problems that occur in cell division, and possible increased infant mortality. With a half-life of about 28.8 years, Sr-90 decays to radioactive yttrium emitting beta particles but not gamma radiation. It accumulates in the skeletal system, hypophysis and ovaries, and subsequently disrupts infant hormonal development, and infant growth. The radiation affects the production of new blood cells, which eventually leads to death. The International Agency for Research on Cancer (IARC) has determined that radioactive strontium is carcinogenic to humans, because it is deposited inside the body and emits beta radiation.

The EPA uses its Safe Drinking Water Act authority to establish maximum contaminant levels (MCLs) for beta emitters, such as strontium-90, in public drinking water. The MCL for beta emitters is 4 millirem per year or 8 picoCuries/L of water.

With a concentration of 28% by weight in the Earth’s crust, silicon is the most abundant element next to oxygen, while silica with a concentration of 42.86% is the most abundant oxide. As silicon occurs mostly as orthosilicic acid (i.e., H4SiO4 or SiO2.2H2O) in water rather than in the ionised state, it is conventional to report its concentration in water as SiO2 rather than Si. Because of the consumption of soluble silica by diatoms and sea sponges, seawater contains just 2.2 mg/L as Si, while groundwater in some places carry SiO2 of over 100 mg/L. In view of the high concentration of Si in the Earth’s crust, life would have been real precarious if excessive ingestion of Si is really harmful.

As Si is a dietary requirement for most living beings, it is considered to be a dietary requirement for humans also. It is required in the development of bone, skin and connective tissue. Shortage of Si is not known, as food provides it in ample amounts without regard to the concentration in drinking water. 

Although ingestion of high Si is not harmful, ingestion of soluble silicon compounds in the human body may disturb phosphorilation, a process by which addition of phosphate (PO4) group to protein enzymes is controlled and thereby cause or prevent diseases such as cancer and diabetes. Further research is required in this direction.

The work of Rondeau and her co-workers of Bordeaux, France indicated that the harmful effects of drinking high-aluminium waters in causing Alzheimer's disease and dementia is substantially reduced by drinking high-silica waters. Further research is required to confirm this finding.

High-silica waters are however harmful in industry because of the formation of boiler scale, or may help to cement other substances into a hard scale, and may be carried over in the steam of high-pressure boilers to form deposits on turbine blades.

Although silica soluble in water is safe, the same is not true with silica dust. Inhalation of fine particles of silicon compounds may cause silicosis particularly in mineworkers, leading to tuberculous, nontuberculous or fungal infections, bronchitis, chronic obstructive pulmonary disease, emphysema, scleroderma, rheumatoid arthritis, systemic lupus erythematosus, sarcoidosis, renal diseases and cancer. 



Dr. R. Jagadiswara Rao, Professor of Geology Retired, Sri Venkateswara University, Tirupati, AP 517502, India

8. Dear Dr. D R Prasada

Dear Dr. D R Prasada Raju,


I have no idea about the permissible limit of Strontium and Silica in drinking water as these parameters are not included in drinking water standards. However, I can make some comments. The extent of Silica in water would depend on the presence of soluble silicate in water. Silicate level higher than 50 ppm may be considered high for drinking water. Although Silicate is an incrustant but does not cause hardness. For Strontium, the limit may be taken as that of Arsenic and can be fine tuned depending upon the solubility of common Strontium salt in water.


With regards,


Dr. Mihir Maitra

Individual Consultant

Water Resource

New Delhi

9. Dear Dr. D R Prasada

Dear Dr. D R Prasada Raju,


According to my knowledge, there is no mention about Strontium level in drinking water by any of the Health Standards.  However, in some literature it was mentioned the upper limit to be 7 PPM and lower limit to be about 2 PPM.


With kind regards,


Dr. D.Muralidharan


National Geophysical Research Institude (NGRI)


10. Water contamination in Srikakulum, Andhra Pradesh

Is anyone able to comment on what is known at this point about the epidemic of acute renal failure in Srikakulum and Uddanom districts of Andhra Pradesh? I have only been able to find that there is suspicion of "silicar" in the water. I assume this means silica? Have the water levels of this and other possible toxins been checked?

Any thoughts or comments would be much appreciated.

U. Pinninti MD
Washington DC

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