What is the best range for TDS in potable water?

Question

Hello everyone.
In our project area in Nepal we have a community water supply system. We found out that the TDS level in the water is 400.
I have researched it on the Internet and I am confused by the permissible range of TDS for drinking water. Can someone tell me what the permissible range of TDS for drinking water is?
Is low TDS in water safe for drinking water? If the TDS is higher, how should we treat the water? We need a cost-effective solution to treat the water.
 Thank you.

Water Network Research · Answer

Permissible range of total dissolve solid (TDS) in drinking water
 
The water network's editors and research team has consolidated an answer to the above question. More inputs from members are welcomed and appreciated.
 Total dissolved solids (TDS) :  comprise inorganic salts and small amounts of organic matter that are dissolved in water. The principal constituents are usually the cations calcium, magnesium, sodium and potassium and the anions carbonate, bicarbonate, chloride, sulphate and, particularly in groundwater, nitrate .TDS is expressed in units of mg per unit volume of water (mg/L) or also referred to as parts per million (ppm)
Permissible range of TDS in drinking water: Different government has different regulations for the TDS level. The U.S. EPA sets the maximum contaminant level for TDS 500 ppm where as WHO has different prescribe limits.
An aesthetic objective of ≤500 mg/L has been established for total dissolved solids (TDS) in drinking water by WHO. At higher levels, excessive hardness, unpalatability, mineral deposition and corrosion may occur. At low levels, however, TDS contributes to the palatability of water. Most people think of TDS as being an aesthetic factor. In a study by the World Health  Organization, a panel of tasters came to the following conclusions about the preferable level of TDS in water:  
Taste of Water with Different TDS Concentrations
Level of TDS (milligrams per litre)
Rating
Less than 300
Excellent
300 - 600
Good
600 - 900
Fair
900 - 1,200
Poor
Above 1,200
Unacceptable
 
Sources of TDS :  Some dissolved solids come from organic sources such as leaves, silt, plankton, and industrial waste and sewage. Other sources come from runoff from urban areas, road salts used on street during the winter, and fertilisers and pesticides used on lawns and farms.Dissolved solids also come from inorganic materials such as rocks and air that may contain calcium bicarbonate, nitrogen, iron phosphorous, sulfur, and other minerals. Many of these materials form salts, which are compounds that contain both a metal and a nonmetal. Salts usually dissolve in water forming ions. Ions are particles that have a positive or negative charge. Water may also pick up metals such as lead or copper as they travel through pipes used to distribute water to consumers.
Methods for removing or reducing the TDS from water
There are 3 common methods for removing or reducing the TDS from the water
1. Distillation :  distillation is one of the most effective forms of treatment and also one of the easiest to understand- untreated water is converted into water vapor, which is then condensed back into liquid form. Most of the contaminants are left behind in the boiling chamber, with the condensed water being virtually contaminant-free.
 
                                                             
                                            Digram : distillation process 
                                            Diagram source :  drinkitclear.com   
2. Reverse Osmosis (RO) :  remove TDS by forcing the water, under pressure, through a synthetic membrane. The membrane contains microscopic pores which will allow only molecules smaller than 0.0001 micron to pass through. Since the molecules of dissolved metals and salts are large compared to the water molecules, the water will squeeze through the membrane leaving the metals and salts behind. A professional Reverse Osmosis system is capable of removing 90-99% of the dissolved mineral salts from water. 
 
                               
                                           Digram: principle of RO
                                           Diagram source: tdsmeter.com/what-is?id=0013                                        
3.Deionization (DI) :  Water is passed between a positive electrode and a negative electrode. Ion selective membranes allow the positive ions to separate from the water toward the negative electrode and the negative ions toward the positive electrode. High purity de-ionized water results. The water is usually passed through a reverse osmosis unit first to remove nonionic organic contaminants.
 
                                                    
                                        
                                           Digram: Simplified potable mixed bed Deionizer
                                           Diagram source : Aquatechnology.net
 
Additional resources
Detailed TDS and safe water information
WHO guidelines for drinking water TDS level
The US EPA's list of National Secondary Drinking Water Regulation 
Distillation method of TDS removal
Reverse Osmosis method for TDS removal
Deionisation method for TDS removal
Carbon filter method for TDS removal 
Read More Related Content On Total Dissolve Solid (TDS) here
Related question: How to reduce TDS level in golf course irrigation water?

Tasleem Hasan · Answer

TDS for potable water
TDS is actually an aesthetic quality of water hence does not have a health guideline value or permissible limit as such. There are no health effects directly attributable to TDS. Being an aesthetic issue, it depends on peoples views but generally good palatability in drinking water should not exceed 600 mg/L. Some people can even tolerate water with TDS of 600-900. 
But also take into consideration that high levels of TDS may cause excessive scaling in pipes, boiling apparatus (heaters etc), so will be bad for the retic system and objectionable to consumers.  Cheers
Tasleem

Anil Dutt Vyas · Answer

TDS levels for drinking water
Please refer WHO link:
regards
Anil
http://www.who.int/water_sanitation_health/dwq/chemicals/tds.pdf

Richard Lasker · Answer

Just asking for a target of "TDS" is equal to asking "how many minerals should I consume." The source, elements and "other" components of TDS are equally of issue then just the number. For example: if the water has a TDS of 300 and all of it is chromium salts is it delicious & safe? How about 400 TDS of Roundup herbicide? 400 TDS of copper salts? So; you ask a question that is dangerous in that it doesn't have significant information for someone to answer. 400 TDS of calcium/,magnesium carbonates is great drinking water....so the answer to your question is to spend some time understanding the source of the water and make your own conclusions from that: river? If river: who is upstream/what industry is upstream? Well-water? If well: type of aquifer, depth of well, rock formation surrounding well. Lake? man-made or natural? Deep water or shallow?

I think you get the picture.... knowledge is power.

rajasegar radhakrishnan · Answer

TDs
Hi,
I dont know in Nepal, In India the TDS range can go upto 1200. When comparing to that yours is a good quality of water. But we have to find out the reason for TDS. If the TDS is because of harmless salts then no issue.
In our coastal areas we have municipal water supply of TDS upto 1000. The TDS is due to Nacl (salt) so, it doesnt have severe impact on our health.
However if you want to treat the water for domestic use RO is the only solution. Nowadays the technology became cost effective.
 
regards
R.Rajasegar

Nikolay Voutchkov · Answer

Permissible TDS Range for Drinking Water
The US Environmental Protection Agency standard for safe drinking water required the TDS of this water to be equal to or less than 500 mg/L.  In practical terms water of salinity lower then 1000 mg/L will be suitable for drinking.  This water however may not be useful for irrigation of citrus fruit, streawberries and some other saline sensitive plants.

Alexander Class · Answer

Permissible range of TDS in water
Dear Grace,
The proper amount of minerals in water is indeed beeing regarded and discussed controversially. Depending on who wants to sell what, the recommendend TDS-values (measured in µS) differ from "close to zero" to "1000 to 3000 is fine". People and companies selling reverse osmosis or destilling technology usually belong to the first, organizations delivering tap or mineral water align among the second group. 
Who to believe? Like always, there is scientific proof for either side. From "only desalinated water can save your life" to "minerals in water are essential and may not be removed" anything can be scientifically proven and be argumented eloquently. But there does definitely not exist any study obeying scientifical standards that could prove a direct relation between TDS-value and any dieseases or death rate. And it is clear why: the TDS-value as such doesnot say which substances are in the water. Water may contain many harmless dissolved solids resulting in a high TDS-value but still beeing healthy water or it may contain little amounts of toxic substances resulting in a low TDS-value but causing severe problems to your health. Thats why in order to define the water quality the least thing necessary is a full analysis of several dozens of substances. But even then you will not get more than a 99% chance of knowing the risks. Even worse, there are many other factors not beeing measured by a chemical analysis.    One thing might be quite interesting for you: Except for the meanwhile rather old-fashioned but still frequently quoted Drs Paul + Patricia Bragg and Dr. Norman Walker whose typical US-American eyes can only see black and white, many scientists and researchers usually (ab)used to underline only one opinion were not absolutely clear in their statemants or changed their opinion when learning new facts about water. Many of them even pointed out, that concerning water quality there are many more factors that we should take into consideration - some we may not even be able to measure. Many researchers in the field of water expressed their astonishment about the complexity of the subject and the humbleness of our knowledge. Many scientists conclude that the less we treat the water with technology the healthier it is for plants, animals and humans.    Examplpes may be Louis-Claude Vincent, commonly quoted to stress the need of treating water with lots of technical equipment like ionizers or alkalizers. He often mentioned that well-water is best and that even flowing in rivers or creeks mostly has harmful effects on water. Another example would be Linus Pauling not beeing ashamed of saying that water in the higher regions of our atmosphere takes up "galactic forces" resulting in never seen physical properties. Or Felix Franks after writing thousands of pages full of head-bursting scientific stuff not understood by more than a dozend scientists around the world confessing frankly that in fact we donot really know much about water and maybe never will.   It may help you to think about the fact that there are natural fountains having beeing cherished as healing fountains for thousands of years by millions of people showing TDS-values of over 2000 and even containing toxic substances like radon or arsenic in amounts a dozen times higher than any tap water would ever be allowed to contain. But nonethelesss everybody is convinced, that their water is pure medicine. So a learned advice from a declared  ex-scientist: Donot care to much about physics and chemistry and learn more to trust your feelings about water.    But if you had trusted your feelings you would not to have asked your question. So I will try to give you a few facts: In the "highly developped" countries in middle or northern Europe TDS-values of under 200 are rarely found in tap water. Most of them are situated between 200 and 700. And 99 % of the population do not care about the TDS-value of their water nor do they waste a thought about reduceing it.   Here my practical advice: With a TDS-value of 400 you are swimming right in the middle. If the TDS-value is not alarmingly high - lets say 1000 or higher - less technology and more nature is always better - and cheaper. Investing in expensive and not environment friendly technology like reverse osmosis or distilling should only be undertaken if the water is extremely "hard", salty or tasting bad. But even then simple and cheap charcoal filters can work fine in most applications. If you absolutely feel the need to reduce the TDS-value think of solar technology using Mother Natures energy to distill water and consider the necessity of really treating 100 % of the water. It may be sufficient - and healthier - to reduce for instance the TDS-value to 200 by mixing the tap water half and half with desalinated water. In any case I would definitely not advise you to do full desalination.    I hope that I could help you.   Best regards - and don't panic!   Alex

Er.Spandan dutta · Answer

Less than 50 TDS
Unacceptable because of lack of important minerals
50 – 150 TDS
Acceptable for Drinking (Excellent – where water is polluted with industrial wastes and sewage)
150 – 250 TDS
Good – Acceptable for Drinking (Healthiest in regard to cardiovascular health.)
250 – 350 TDS
Good – Acceptable drinking (Healthy in regard to cardiovascular health.)
 
Water with TDS level less than 100 has the high dissolvent capacity, which even dissolves a small quantity of plastic, in which it is kept. The dissolved plastic in water can cause cancer and can also reduce immunity. Plastic in water can also become a carrier for other toxins, heavy metals, arsenic, fluoride, or aluminum.

Kumar Sarangapani · Answer

Even RO water when used for potable purposes has to be remineralized. The human body requires a certain amount of salt to maintain electrolyte balance in the human system. Therefore it has to have TDS around 200-300 PPM, to have a feeling of quenching of thirst.

Kevin Chen · Answer

grace P 
The higher the number of PPM (parts per million) means more particles and contaminants that not only make water taste bad but can also be bad for your health. What is a good number?  Apparently the World Health Organization says that water with a TDS (total dissolved solids) of 1,000 PPM is “acceptable” and under 600 PPM is “good.”

What is the best range for TDS in potable water?

Taxonomy

15 Answers

1 Comment

1 Comment

Less than 50 TDS	Unacceptable because of lack of important minerals
50 – 150 TDS	Acceptable for Drinking (Excellent – where water is polluted with industrial wastes and sewage)
150 – 250 TDS	Good – Acceptable for Drinking (Healthiest in regard to cardiovascular health.)
250 – 350 TDS	Good – Acceptable drinking (Healthy in regard to cardiovascular health.)

Level of TDS [mg/l]	Rating
Less than 300	Excellent
300 - 600	Good
600 - 900	Fair
900 - 1,200	Poor
Above 1,200	Unacceptable

Taste of Water with Different TDS Concentrations
Level of TDS (milligrams per litre)	Rating
Less than 300	Excellent
300 - 600	Good
600 - 900	Fair
900 - 1,200	Poor
Above 1,200	Unacceptable