Do you have any plans to buy a new purifier? You must have heard about TDS, but do you know what TDS means? Many of the water purifiers filter the water and make it drinkable. But there is more to it and you should know about TDS as well.
To know more about TDS, you should read this article. We can also look at aspects in which you can measure TDS. Besides, we have also discussed the appropriate amounts of TDS and how to remove TDS in the water.
What is TDS?
TDS stands for “Total Dissolved Solids.” You must have studied in Chemistry that H2O is the chemical formula for water. Therefore, a water molecule contains two hydrogen atoms and one oxygen atom. However, several salts are available in the water, such as calcium, magnesium, potassium, fluorides, carbonates, sulfates, and many others.
There are also heavy metal impurities such as arsenic, lead, and mercury in the groundwater and other water bodies such as rivers, streams, and wetlands. However, these components are harmful to health. Therefore, to remove these pollutants, you need appliances like water purifiers.
Moreover, excessive consumption of salt consumption is detrimental to health. Therefore it becomes necessary to check the levels of TDS in water.
Necessity of TDS
Clean water does not have any flavour. It is essential to impart the appropriate flavour and nutrition benefits, such as calcium, magnesium, and potassium. However, you can ensure to preserve the TDS amounts. Now let’s see the appropriate TDS rate.
Acceptability Levels of TDS
You can determine the acceptability levels of TDS in water by the Bureau of Indian Standards (BIS). TDS of up to 500 mg/litre is considered appropriate, according to the BIS. However, you can understand things using the following table.
|TDS Levels in mg/litre||Why Acceptable|
|Less than 50||TDS level less than 50 does not constitute necessary minerals and nutrients, therefore this is not an acceptable level for drinking.|
|Above 500 and up to 1200||Any level over 500 is not acceptable for drinking purposes. But you can use a water purifier to remove the TDS from water. |
It will help in giving water with TDS level below 500. And according to BIS this TDS level is acceptable for drinking purposes.
|Above 1200||Water having TDS levels over 1200 is not good for drinking purposes|
|350 to 500||The BIS gives this certificate with this TDS range in water as acceptable for drinking purposes|
|150 to 250||You can call it the most acceptable healthiest level of TDS in water resources.|
|250 to 350||Many places consist of water with this TDS range and people find it considerate to drink. |
Although it's an acceptable level.
TDS – Palatability Levels
There is a disparity between the TDS rate of acceptability and palatability in water. Besides, continuing to calculate the volume of TDS in water, we will first look at the palatability levels of TDS.
|TDS Levels mg/litre||Palatability Quotient|
|Any level less than 300||Amazing taste|
|More than 300 and up to 500||Acceptable Levels|
|500 to 900||Far level after removing TDS level from the water.|
|Above 900 to 1200||Many water purifiers eliminate TDS levels between this range as well. |
But water with TDS level in this range consists of poor palatability.
|Above 1200||Unacceptable range.|
How to measure TDS levels in water?
1. Digital TDS Meter ( Instant result )
Digital TDS Meter is one of the easiest of all the instruments we can use to calculate the TDS amounts of water. Besides, it has another benefit of an Automated TDS Meter.
You do not have to use analytical formulas to take any measurements and do calculations. But you get instant results, and that is too precise. You can find below the method to use the digital TDS Meter :-
Measure the temperature of the water sample
- Switch on the meter
- Press the ”TEMP” button.
- Reading in Degrees Celsius.
- Return to the TDS mode
- Press the ”TEMP” button again.
Measure the TDS level
- Remove the safety cap, and the meter will turn on.
- Up to the full immersion level, immerse the TDS meter into the water sample. It usually is 2 inches. Therefore to signify this amount, you will find a label on the meter.
- Air bubbles may form while doing it. However to eliminate these air bubbles, stir the meter softly.
- Wait for the reading to settle for about 10 to 15 seconds.
- Click and delete the ”Keep” button from the water to display the reading.
- Different meters show different signs. You have to multiply the reading by 10 in those conditions.
- After using the TDS meter, shake off the excess water from the meter and replace the protective cap.
Take the following precautions while using the TDS meter
- It is not watertight on the Optical TDS meter. Therefore, you can make sure the meter does not fall below the full degree of immersion.
- Do not expose the meter to the sun.
Where can you get these digital TDS meters?
You will find these Wireless TDS meters for a few hundred rupees. However, it is available at medical stores and other departmental stores. Besides, you can also buy it directly from online shopping sites like Amazon. Moreover, these meters have different calibrations available. There is also a calculation scale of 0 to 5000 ppm for TDS meters.
2. Electrical Conductivity Meter Method
We have mentioned that both organic and inorganic salts constitute TDS. However the most popular approach in use today is the Electrical Conductivity Meter technique. To compute the level of TDS in water, follow these steps.
Apparatus required for measuring the TDS.
- A sterilized glass beaker free of dust
- Keep the water sample around 250C
- Electrical conductivity meter
The electrical conductivity meter works to measure its resistance by releasing an electrical current into the bath.
Measure the conductivity
Make sure to keep the meter on a smooth surface. Turn the conductivity meter on and put into the water the measuring lead.
- Before stabilizing, the reading will fluctuate a little for a few seconds. After it stabilizes, you can write down the readings.
- This measurement shows the purity of water. The reading is in µS (micro Siemens). However, the lower the value, hence the purity of water. Water in its purest H2O form has 0 µS.
Use the data for the following formula to know the TDS level in the water
Formula to know the TDS level in water is mentioned below:-
TDS (in mg/litre) = KE (Correlation factor) X EC (Conductivity)
KE, the Correlation factor varies due to the nature of the liquid and the water temperature. Moreover, it depends on the weather conditions. The value of KE varies from 0.55 and 0.8.
- To determine the KE factor, you should know the water sample’s temperature and the current pressure conditions.
- For the KEY factor of approximately 0.67 keep the water temperature at around 250C
- According to BIS, you can drink water with less than 500 mg/litre.
- However, water with higher TDS levels in the range up to 1200 may lead to water purification. Also, you can use RO water purifiers to make it suitable for use.
With the help of this formula, you can measure the TDS levels in almost all liquids. However, different liquids will have a specific KE.
3. Using Filter Paper and a Weighing Scale
This TDS levels calculation method is the standard one. Also, at home, you can do it quickly. Also, you don’t don’t need to obtain an electrical conductivity unit. Let us look in brief at this process.
- A clean and sterilized glass beaker
- Sample of for measuring TDS levels
- Filter paper
- Evaporating dish
- Stirring stick
- The pipette should be large enough to collect a minimum of 50 ml
- Weighing scale
Weigh the empty evaporating dish
Weigh the empty evaporating dish using the weighing scale. Make sure that the dish is dry and clean of all particulate matter. Besides, note down the reading in mg.
Stir the sample water
Make sure to stir the water so that the particulate matter mixes uniformly in the sample.
Collect the water sample
Collect a minimum of 50 ml of a water sample using the pipette. Ensure that when extracting the sample, you stir the liquid frequently. Although. Make sure the particulate matter does not settle at the bottom of the flask. It won’t offer a detailed reading. Although you can ask your partner to keep swirling the liquid while you collect the sample you find it hard to do so.
Extract the filtrate
While doing so, pour the water sample to another container using the filter paper. Besides, to make sure that the particulate matter is out of filter paper, repeat the process at least three times.
Weigh the evaporating dish using the filtrate
To know the weight of the evaporating dish, move the filtrate and allow it to dry entirely. Moreover weigh the evaporating dish and the filtrate together and remember the note down the reading in mg.
Use this formula
TDS = [(A-B) X 1000]/ml sample
(A = weight of the evaporating dish and the filtrate and B= the weight of the evaporating dish alone.)
Note that you had used 50 ml of the water sample. Hence, the ml sample value will come 50 in this case. Also note down the final value of TDS in mg/litre.
Ideally, the TDS level should be below 500 for the water to be fit for human consumption. However, you can use RO and other water purifiers to eliminate TDS if the TDS levels show more than 500. Besides, any value over 1200 mg/litre is unacceptable, according to BIS.
Need to remove excess TDS
We have shown that no single contaminant has TDS. It is a combination of different salts, including calcium, magnesium, and potassium. For our good health, these salts are essential.
However, in our region, water supplies contain other unacceptable impurities, such as human and industrial waste. But there are cases of poisoning of water supplies by arsenic, mercury, and lead as well.
These impurities are a threat to health. Likewise, TDS amounts over 500 ppm may also harm our overall well being. Therefore, before drinking it, you must remove the excess TDS from the water.
Boiling the water and allowing the vapours to cool down are part of this process. Moreover, the salts linger in the boiling water solution, the resulting water will have no TDS. It is the best mechanism to eliminate TDS.
A standard method of removing TDS is Reverse Osmosis (RO). This technique is used for nearly all the water purifiers present in the market. However, this approach involves water moving through a semipermeable membrane containing microscopic pores that facilitate the passage of molecules smaller than 0.0001 microns.
The molecules of TDS are comparatively heavier, so they get stuck in the membrane. Besides, RO is one of the better strategies because it eliminates the TDS from drinking water.
Water moves between two electrodes through the deionization process (positive and negative). And if they pass toward the negative electrode, the ion-selective membranes cause the positive ions to detach from the water. Pure water is the resulting water.
However, after subjecting the water to RO treatment, it is safer to use this technique. It helps to eliminate non-ionic organic contaminants.
We have mentioned the TDS test in detail and studied how to calculate the rate of TDS as well. Although, we have also looked at removing unnecessary TDS and ensuring that acceptable TDS amounts are included in the resulting water.
You can use the formula mentioned above to check the TDS level. However, you will need someone to help you with it. But the best part is that you can check it quickly at home without spending any money.
However, you will need to collect some necessary apparatus and material to perform the test. It will be beneficial for you as it will get pure drinking water.