Have your bought or planning to purchase a new water purifier for home? I’m pretty sure that you might’ve come across the word ‘TDS’.
What is TDS? How to Measure it? We shall discuss everything about TDS of water, in this article.
What is TDS?
TDS stands for “Total Dissolved Solids” in water.
The chemical formula of water is H20, which means there are 2 atoms of Hydrogen and 1 atom of Oxygen in a single molecule of water (in its purest form).
But, we are not fortunate enough to drink pure water in our current society as our groundwater is being mixed with dangerous chemicals and heavy metal impurities like arsenic, lead and mercury.
So, we’re basically missing out on all the essential salts that come with water like calcium, magnesium, fluorides, potassium, carbonates, sulfates and many others.
Therefore, there is a definite need for appliances like water purifiers in order to filter out such harmful contaminants from the groundwater and make it safe for drinking.
Acceptable TDS Levels
According to BIS (Bureau of Indian Standards), the safest or acceptable TDS levels in water is up to 500 mg/litre.
Anything above that is not suitable for human consumption.
Here is a complete list of TDS levels and their acceptance ratio in India.
| TDS Levels (mg/litre) | Acceptable or Not Safe & Why? |
| Less than 50 | Such low TDS levels in water is not good as you’ll be missing all the required minerals responsible for healthy growth. |
| 50 to 150 | Acceptable; Because there are different types of pollutants involved. |
| 150 to 250 | Healthiest TDS level; Best for cardiovascular health |
| 250 to 350 | Acceptable; Most groundwater in India has TDS levels in this range. |
| 350 to 500 | Acceptable; BIS says TDS levels up to 500 is ok for human consumption |
| Above 500 and up to 1200 | Not Safe for Direct Consumption; You may use an RO to purify this water and bring down the excess TDS levels to safety. |
| Above 1200 | Unfit for human consumption; Use an advanced water purifier with multi-stage filtration technology to purify water with such high TDS levels. |
Palatable TDS Levels
It refers to the taste of the water and not acceptance. So, there is a clear difference between acceptability and palatability.
| TDS Levels (mg/litre) | Palatability |
| < 300 | Tastes good and excellent for drinking. |
| Above 300 and up to 500 | Acceptable or Ok taste |
| 500 to 900 | Not acceptable; Use an RO to eliminate excess TDS. |
| Above 900 and up to 1200 | Poor palatability; Only use a high-quality RO purifier to bring down the TDS levels. |
| Above 1200 | Unfit range; Advanced water purifiers can only bring down such high TDS content in water. |
How to Check TDS Level of Water at Home?
There are currently 3 different methods to measure the TDS levels in the water, which includes digital TDS meter, electrical conductivity meter and filter paper ‘n’ weighing scale method.
Out of these three, the first method is the most easiest and cost-effective method to measure the TDS of water at home.
What is Digital TDS Meter?
A digital TDS meter is undoubtedly the easiest method to determine the levels of TDS in water.
You don’t have to do any math as the TDS meter does all the calculations for you.
Before using the TDS meter, make sure that you should not expose it to direct sunlight and do not dip it beyond the max immersion level (provided on the meter) as it would result in malfunctioning of the device.
How to Use a TDS Meter to Check the Quality of Water?
- Remove the protective cap and switch on the TDS meter using the button provided.
- Take the sample water (½ glass is enough) and immerse the meter into the water (usually 2 inches). You’ll find a marking on the meter as well.
- If you find any air bubbles in the water, just stir the meter to remove them.
- Wait for 10 to 15 seconds for the TDS reading to stabilize.
- Press the ‘Hold’ button and take the meter out of the water.
- There’s your actual TDS level reading. In case if you find X10 symbol, you’ll need to multiply the reading by 10.
- Once done, shake the meter to drain any excess water and replace the protective cap.
You can find these digital TDS meters at your local medical stores at reasonable costs. You may also buy them online from stores like Amazon.in.
They are available in various calibrations and measurement ranges up to 5000 ppm.
Why Should You Remove Excess TDS of Water?
I’m sure, by now, you’ve understood that TDS is not a single contaminant and a mix of essential salts like calcium, magnesium, potassium etc…that improve our health.
Unfortunately, we’re living in a polluted environment where the industrial & human wastes get mixed in the rivers making it unacceptable or unsafe for consumption as the water is contaminated with arsenic, mercury and lead.
So, if you don’t eliminate these impurities, your health will get affected in a negative way.
Therefore, water with TDS levels above 500 ppm should be purified using an RO before consuming it.
How to Eliminate Excess TDS Levels in Water?
There are actually 3 methods you can use to eliminate the excess TDS in water.
1. Distillation
It involves boiling water and allowing it to cool down. The resultant water is safe for human consumption as it is bereft of TDS and has all the essential salts in it.
This is by far the easiest and cost-effective method to remove TDS.
2. Reverse Osmosis
Distillation process usually needs a lot of time, especially if you’ve more water consumption at your home.
That is where the Reverse Osmosis (RO) process comes into place.
Most water purifiers in the market use the RO technology to kills the contaminants in the water and make it acceptable for drinking.
It works by passing the water through a semipermeable membrane where the microscopic pores allow only smaller molecules (0.0001 microns).
Since the TDS molecules are larger, they get trapped in the membrane and are removed from the resultant water.
So, complete elimination of TDS is possible with Reverse Osmosis method.
3. De-Ionization
The process works by passing the water through 2 electrodes, namely positive and negative.
The ion-selective membranes separate the positive from the negative and the resultant water is just pure drinking water.
However, it is recommended to use the deionization process only after the RO treatment as it helps in removing the non-ionic organic contaminants.
Final Word:
Almost every water source comes with certain TDS levels and we should ensure to check whether the water is acceptable or unsafe before drinking. The best way to do so is to use a TDS meter and then use an RO purifier to eliminate the contaminants if any from the water.
Thanks for the detailed guide
Wow…I never thought checking TDS levels of water was this easy. Thanks for the helpful guide.