What is TDS in Water and How it Affects Your Health?
What is TDS in Water?
TDS (Total Dissolved Solids) represents the total concentration of all the dissolved substances in water.
TDS in water comprises inorganic salts and a small amount of organic matter.
Common inorganic salts that can be found in water include calcium, magnesium, sodium, and potassium, which are all cations, carbonates, bicarbonates, chlorides, nitrates, and sulfates, which are all anions. Cations are positively charged ions and anions are negatively charged ions.
The full form of TDS is Total Dissolved Solids.
The most important thing to note here is that the impurities, like dust, dirt, mud, and rust, do not constitute Total Dissolved Solids. This is because these impurities remain suspended (or settle at the bottom) in water and do not dissolve.
Dissolved solids can easily pass through a filter with 2-micrometer (or smaller) pores. But the suspended/settleable solids can be easily filtered out with such a filter.
From Where Do These Dissolved Solids Come in Water?
TDS in water supplies can originate from both natural sources and as a result of human activities. Sewage, agricultural and urban run-off, and industrial wastewater are the most common sources of Total Dissolved Solids in water.
Rivers flowing through mountains contain water with high levels of dissolved solids because the water flows through rocks that have mineral deposits and high salt content.
The most common dissolved solids are calcium, magnesium, phosphates, nitrates, sodium, potassium, and chloride. Mostly found in groundwater and river water, these are naturally occurring and are harmless to the human body.
However, some constituents of TDS like pesticides, lead, arsenic, and fluoride can be very harmful to human health. These constituents enter water as a result of human activities like sewage, agricultural and urban run-off, and industrial wastewater.
Why Do You Need to Measure Total Dissolved Solids?
Because testing the level of TDS in your water is the easiest way to analyze the overall quality of your drinking water.
Although there is no proof of any negative health effect of high or low TDS levels, it is used as an indicator of the presence of a broad array of chemical contaminants.
The Bureau of Indian Standards (BIS) has set the acceptable limit of TDS in drinking water at 500 mg/L.
Drinking water, with TDS levels higher than 1000 mg/L, is generally considered unfit for human consumption. A high level of TDS is also a direct indicator of potential concerns and calls for a thorough analysis.
Mostly high levels of TDS in drinking water are a result of the high concentration of minerals like calcium and magnesium. These minerals have little or no short-term health effects. But harmful and toxic contaminants like lead, arsenic, cadmium, nitrate, and others, have a serious effect on your health.
If you are living near highly polluting industrial zones and agricultural regions with a long history of using chemical fertilizers and pesticides, then there is a very high probability of these toxic contaminants mixing with the water source.
In such a case, apart from testing the TDS level of the water, you should also get your water tested in a laboratory to find the presence of any harmful or toxic contaminants.
| Harmful Constituents of TDS | Beneficial or Harmless Constituents of TDS |
| Aluminum | Zinc |
| Arsenic | Magnesium |
| Barium | Potassium |
| Cadmium | Calcium |
| Chlorides | |
| Copper | |
| Fluoride | |
| Lead | |
| Nitrates | |
| Sodium | |
| Sulfates |
In areas where the TDS content of the water supply is very high, the individual constituents should be identified and the local public health authorities consulted.
What Happens to the Water When TDS is High?
a) The high concentration of dissolved solids in water causes water filters to wear out sooner. If the water at your home has high levels of TDS then you will have to replace the filters and membranes more frequently as compared to homes that have low TDS water.
b) A high level of TDS in water makes the water taste bitter and salty. In a study conducted by the World Health Organization (WHO), the palatability (acceptable taste) of drinking water has been rated by panels of tasters about its TDS level as follows:
| TDS LEVEL (MG/L) | RATING |
| Less than 300 | Excellent |
| 300-600 | Good |
| 600-900 | Fair |
| 900-1200 | Poor |
| Above 1200 | Unacceptable |
c) Bathing with high TDS water makes your skin rough and dry. It also damages your hair making them rough and dry, causing dandruff and hair fall.
d) Calcium and magnesium, two minerals commonly found in TDS, can cause water hardness, scale formation, and staining. High levels of minerals in water lead to scaling on bath fittings, water pipes, water heaters, and household appliances.
e) The high TDS level makes water hard. Apart from drinking, hard water poses several other challenges like soaps and detergents do not produce as much lather.
Are you worried about excessive skin dryness and sudden hair fall or dandruff? Chances are it is because of the calcium and magnesium minerals that make your water hard. Changing your soap or shampoo is not the solution. The solution is quite simple, you need to use a hard water softener for your bathroom. Hard water softeners are small, affordable, and easily fit on any tap or showerhead. We have written a detailed post on how hard water softeners can bring back the softness and shine of your skin and hair. This post also covers the best water softeners reviewed by our experts.
Click to read: What is the Difference Between TDS and Hardness of Water
Health Effects of High TDS in Drinking Water
It is a widely known fact that high levels of TDS in drinking water can give water a bitter or salty taste, but it is not harmful to your health. Minerals like calcium and magnesium, which are often the reason behind high TDS levels, are beneficial to your health.
However, if the TDS level of your drinking is above 500 PPM then it is recommended that you get the water tested for harmful impurities like lead, arsenic, mercury, fluoride, etc.
Click to read: How to Reduce TDS Level in Water?
A high TDS level is usually not a health hazard as long as the dissolved solids are essential minerals and not harmful heavy metals and chemicals.
No health-based guideline value is proposed for TDS. However, drinking water guidelines are available for some of its constituents, including lead, arsenic, cadmium, fluoride, nitrate, etc.
If you suspect or if the laboratory tests point to the presence of lead, arsenic, mercury, fluoride, or other harmful impurities then you should use a multi-stage RO water purifier.
You may want to look at the top RO water purifiers for purifying high TDS water.
Is Low TDS Water Harmful?
Water with an extremely low level of TDS is undesirable for most consumers because of its flat, dull taste.
Also, demineralized or very low TDS water is not suitable for athletes and people with highly active lifestyles. But for most people, drinking water with a low TDS value doesn’t pose any health concern.
Water is not the only source of essential minerals like calcium and magnesium. The food that you eat also contains these minerals. Your body’s mineral requirement can be easily fulfilled by the food that you eat.
Apart from the dull taste, water with excessively low TDS is more corrosive and can leach harmful metals such as lead or copper from plumbing pipes and hardware.
Drinking water with moderate amounts of TDS is the best. Water with moderate TDS tastes better than water with very low or very high TDS levels.
What are the Guidelines for TDS in Drinking Water in India?
World Health Organization (WHO) report on TDS in drinking water points out that reliable data on possible health effects associated with TDS in drinking water is not available.
No health-based guideline value is proposed for the ideal TDS of drinking water. Because TDS in water can be high because of many factors so, in areas where the TDS content of the water supply is very high, the individual constituents should be identified.
The Bureau of Indian Standards (BIS), the organization that defines the drinking water quality guidelines in India, has set the acceptable limit of TDS in drinking water at 500 mg/L. However, the guidelines also mention that in case no alternative source of drinking water is available, then this acceptable limit can be relaxed to 2,000 mg/L. The BIS report also mentions that if the TDS level of the drinking water is higher than 500 mg/L then this may result in a decrease in palatability (acceptable taste) and may cause gastrointestinal irritation.
| TDS LEVEL (MG/L) | REASONS FOR ACCEPTABILITY / NON-ACCEPTANCE |
| Less than 50 | Safe but not ideal. You may find it tasteless because water with such a low TDS level is devoid of essential minerals. |
| 50-150 | Acceptable. However, a TDS level in the range of 80-150 is considered ideal. If you are using an RO water purifier then make sure the TDS level of purified water is not below 80 mg/L. |
| 150-250 | Not acceptable. Use an RO water purifier with a TDS controller or mineraliser. |
| 250-350 | Acceptable. Most urban Indian homes have access to water in this TDS range. |
| 350-500 | Acceptable. As per the BIS guidelines, a TDS level below 500 mg/L is acceptable. |
| 500-900 | Not acceptable. Use an RO water purifier with a TDS controller or mineraliser. |
| 900-1200 | Not acceptable. Use a RO water purifier with a TDS controller or mineraliser. |
| 1200-2000 | Not acceptable and not fit for drinking. Choose a RO water purifier that can purify water with up to 2000 mg/L. |
| Above 2000 | Do not drink. Most home water purifiers can’t purify water with a TDS level over 2000 mg/L. |
How is TDS Measured?
There are two methods of measuring Total Dissolved Solids in water: gravimetric analysis and conductivity.
Gravimetric Method
The gravimetric method is the most accurate but it is time-consuming. In this method, the liquid solvent or water is evaporated and the weight of the remaining residue is measured to calculate the TDS level. This method is ideal in case of high TDS concentrations and if inorganic salts constitute the majority of TDS.
Electrical Conductivity
Electrical Conductivity is the most popular and also the easiest method to find out the TDS of drinking water. The electrical conductivity of water is directly related to the concentration of dissolved ionized solids in the water. TDS meters work on the same principle of conductivity. Although this method is not as accurate as the gravimetric method, it is the quickest and easiest way to find an approximate value for the TDS level in the water.
You may like to check our detailed post on how to check the TDS level of water at home.
Click to read: Do Water Softeners Reduce TDS?
Conclusion
Whether the TDS level is a cause of worry or not depends on the kind of minerals, metals, and chemicals that make up total dissolved solids in your water supply. Unfortunately, this is not as easy as finding the TDS level as it requires more advanced testing.
TDS is not the only indicator of how pure or contaminated your drinking water is. TDS is only one of several indicators of the purity of water. Water may contain a whole lot of contaminants like mud, dust, rust, sand, bacteria, viruses, cysts, and more.
The water purification technology you use depends on the source and quality of the water. For more details on how to find the best water purifier for your home, you should check the water purifier buying guide.
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Thanks for these information. But i shall be glad if I get remarks of my enquiry which is – my ro giving tds 25 when raw water tds is 824. Is it correct. I am using kutchina local ro. Please guide. Company told 90 to 95 reduction. Please guide. Tds control is of no use.
You do not have to worry, as long as you are able to meet the dietary requirements for essential minerals like Calcium and Magnesium with what you eat. We recommend adjusting the TDS controller to get purified water with TDS of at least 50 PPM.