How To Measure TDS In Water?

Total dissolved solids (TDS) measure the number of minerals, salts, metals, and other substances in water. Knowing the TDS water level can be essential for industrial and residential use. To measure the total dissolved solids in water, you need a unique instrument called a TDS meter. These meters measure the electrical conductivity of water, which is related to the number of dissolved solids in it. The higher the level of TDS, the higher the electrical conductivity, and vice versa.

TDS meter

TDS meters are relatively inexpensive and easy to use. To use one, dip the electrode end into a sample of your water and wait for the meter to give you a reading in parts per million (ppm). The EPA recommends that water sources with 500 ppm or less TDS levels are safe for drinking and other uses.

What Does TDS Mean?

Total dissolved solids (TDS) measure the number of minerals and other inorganic substances dissolved in water. The most common types are calcium, magnesium, sodium, potassium, bicarbonate, chloride, and sulfate. These substances can come from natural sources such as soil erosion or runoff into bodies of water or artificial sources such as agricultural runoff or industrial wastewater. The presence of these solids can make water taste bitter, salty, or metallic and can discolor clothing when used for laundry.

How To Measure TDS In Water?

Measuring Total Dissolved Solids (TDS) in water is essential to ensure safe drinking water. TDS measurement allows for comparing the levels of dissolved solids between two different water sources and can be used as an indicator of water quality and safety. There are several ways to measure TDS in water. The most common methods are described below;

How to measure TDS in water

Method 1: Using Digital TDS Meter

Step1.Remove the protective cap of the Digital TDS meter: Take the protective cap off the Digital TDS meter used to measure TDS. Remove the protective cap of the digital TDS meter.

Step 2. Switch it ON: After removing the cap, switch it on.

Step 3. Dip the Digital TDS meter in the water: place the probe of a digital TDS meter into the sample water, ensuring it is fully submerged.

Step 4. Stir the Digital TDS meter to remove the air bubbles: To ensure accurate readings, stirring the digital TDS meter before and after each measurement is essential. This helps to remove any air bubbles that may have built up in or around the probe.

Step 5. Wait for 10-15 seconds: After the electrode is fully submerged, wait 10-15 seconds for a stable reading of TDS levels. This allows time for the ions in the water sample to move around and settle into a stationary state which will be accurately measured by your TDS meter. After 15 seconds, check the reading.

Step 6. Multiply the reading by 10: the number you obtain is the concentration of TDS in parts per million (ppm). For example, if the ppm meter reads 200, multiply it by 10 to get 2000 ppm.

Step 7. Shake off the excess water from the TDS digital meter: Removing the excess water from your TDS meter after use is essential. This will ensure that your readings are accurate and that your device is not damaged due to dampness. Hold the probe of the meter in one hand, then shake off any drops of water on and around it with the other hand.

Step 8. Replace the protective cap: Replace the protective cap on your TDS meter. This will help keep any dirt particles from entering the device as you measure water samples.

Method 2: Using Filter Paper And A Scale:

Required Apparatus:

  • A clean & sanitized glass container
  • Water sample for TDS determination
  • Filter paper or Layers of Cotton
  • Evaporating dish
  • A sterile stirring stick
  • A pipette to take a 50ml water sample
  • A weighing machine or scale

Step1. Weigh The Evaporating Dish: Take the evaporating dish and measure its weight. Record this measurement as ‘W1’ (in grams).

Step 2. Stir The Water Sample: First, stir the water sample to ensure all particles are dissolved, and nothing is settled on the bottom of the container. If solid particles or residues are present in the sample, it will give a false reading when you measure TDS.

Step 3. Collect The Water Sample: The first step in accurately measuring a water sample’s Total Dissolved Solids (TDS) is to collect it. The water sample should be taken at a depth of around 20 cm and must be free from any contaminants that may affect the measurements. Special sampling bottles can be used for this purpose, as they are designed to minimize contact with air and other contaminants.

Step 4. Check The Temperature Of The Water Sample: It is essential to ensure that the temperature of the water sample is within a specific range when measured. Water samples should be at or below 25°C (77°F) to accurately measure TDS levels. If the sample temperature is higher than this, it should be cooled before proceeding.

TDS structure

Step 5. Extract The Filtrate: To measure the TDS (total dissolved solids) in water, one needs to extract a filtrate. This can be done by boiling the water and then cooling it or running the sample through a filter paper to remove impurities like dust particles or un-dissolved solid contaminants. The clear liquid which is extracted is the filtrate.

Step 6. Weigh The Evaporating Dish With The Filtrater: After you have filtered the water sample, the next step is to weigh the evaporating dish containing the filtrate. This will give you a measure of how many solids were in the original water sample. An accurate balance is essential, as even small amounts of difference can skew your results.

using filter paper

Method 3: Using Electrical Conductivity

Apparatus Required

  • A sterilized glass beaker, free of dust
  • Water sample
  • An electrical conductivity

Place the beaker on a flat surface: Place the sterilized glass beaker on a flat surface, then fill it with your water sample. Ensure all the air bubbles are removed to get an accurate reading.

Please switch it on: Once the beaker is filled, turn on your electrical conductivity meter and switch it to the appropriate setting for measuring TDS.

Insert the measuring lead into the water sample: Carefully insert the measuring leads into the water sample and record the reading that appears on the electrical conductivity meter.


Interpret TDS readings: The higher the reading, the more total dissolved solids are in your water sample. The results may be expressed in parts per million (ppm) or milligrams per liter (mg/L), depending on the type of instrument used. It’s essential to consider your instrument’s accuracy when interpreting these results.

Please wait a while and let the reading stabilize: Once you have taken the reading, wait a few minutes before recording it. This will allow any fluctuations in the electrical conductivity to even out and give you an accurate result.

Note down the reading: Once the reading has stabilized, record it to measure the TDS in your water sample accurately.

TDS meter using electrical conductivity

What is the Ideal TDS Level of Drinking Water?

The ideal TDS level of drinking water is generally agreed to be around 300-500 parts per million (ppm). Anything below 200 ppm is considered very low, while anything above 500 ppm may have an unpleasant taste or smell. It’s important to note that the acceptable amount of TDS in drinking water can vary depending on which country you are in or which organization is setting standards.

How Does Total Dissolved Solids Become A Problem?

High levels of Total Dissolved Solids (TDS) can lead to various issues in water, such as poor taste and odor, scaling buildup in pipes and other plumbing fixtures, reduced effectiveness of water treatment chemicals, and increased turbidity. In high enough concentrations, TDS can also be harmful to aquatic life.

What Are The Health Risks For Total Dissolved Solids?

The presence of high levels of Total Dissolved Solids (TDS) in water can have profound health implications. A TDS level that is too high can lead to a variety of illnesses, including:

Gastrointestinal distress: Higher levels of TDS can cause stomach discomfort, nausea, and vomiting. In extreme cases, ingesting water with high levels of TDS can lead to kidney stones and bladder infections.

Gastrointestinal distress

Skin irritation: Prolonged exposure to water with excessive TDS can cause skin irritation, rashes, and dryness. In addition, the minerals found in water with high TDS levels can clog pores and increase the risk of acne.

Hair loss:  An abundance of TDS in water can lead to hair loss due to the minerals and other contaminants that can strip away natural oils from the scalp.

Damage to home appliances: High water TDS levels can damage plumbing systems, washing machines, dishwashers, and other household appliances. The accumulation of minerals can cause clogs, rust, and other damage.

What Is the Difference Between TDS And Hardness?

Total Dissolved Solids (TDS) and Hardness (calcium and magnesium levels) are two very different measurements in terms of the components that make up your water.

TDS measures the concentration of all dissolved solids in a sample of water; whatever the substance may be, it could include calcium, magnesium, nitrates, sulfates, phosphates, and more. Measuring TDS can help you determine how many different components are dissolved in water, which can provide valuable insight into the overall health of your water.

On the other hand, Hardness measures precisely the amount of calcium and magnesium,  two essential minerals often found in drinking water, present in a sample of water. Measuring Hardness can give you an idea of the mineral composition in your water and how it will affect its taste, odor, and other characteristics.

TDS and Hardness are often interrelated; more dissolved solids tend to lead to higher Hardness levels, but this isn’t always the case. Measuring TDS and Hardness is important to get the complete picture of water quality. This can help determine if your water is safe for drinking, cooking, bathing, and other activities.


Does a high TDS level always mean the water is unfit for consumption?

No, not necessarily. Total Dissolved Solids are generally measured in parts per million (PPM), and levels below 500 PPM usually indicate that the water is fit for drinking. However, this can vary depending on the type of minerals present in the water, as some may be more harmful than others.

How do you reduce the TDS level in drinking water?

Reducing the TDS level in drinking water is a multi-step process that involves filtration, purification, and other water treatments.

Is 200 TDS Water Safe For Drinking?

The answer depends on what type of water you are considering. Generally, it is recommended that the Total Dissolved Solids (TDS) levels in drinking water should be below 500 parts per million (ppm). If a sample of drinking water has a TDS content above 500 ppm, it may contain pollutants that can lead to potential health risks.

What are the substances causing high levels of TDS in water?

Total Dissolved Solids (TDS) are inorganic and organic substances dissolved in water. Sources of TDS can include natural ionic compounds from soil, minerals, living organisms, and any artificial chemicals. Some familiar sources of high TDS levels include fertilizers, agricultural runoff, sewage effluent, wastewater, and industrial wastewater discharge. Inorganic salts are the most common substances causing high levels of TDS in water, including calcium and magnesium carbonates found naturally in soil.


Measuring TDS in Water - infographic
Measuring TDS in Water – infographic

Measuring Total Dissolved Solids (TDS) in water is a simple process that anyone can do with the right equipment. The most reliable method for measuring TDS is using a digital instrument such as a handheld meter. This will give you the most accurate results and allow you to make informed decisions about your drinking water. Additionally, if the TDS level exceeds the acceptable safe levels, consider installing a reverse osmosis system or another filtration system to reduce the number of dissolved within safe drinking standards and solids in your drinking water.

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