Water is a powerful drink and a universal solvent. As such, it can dissolve and absorb molecules from several substances. The total dissolved solids (TDS) level is the number of particles dissolved in a volume of water.
TDS has two forms: organic and inorganic. Understanding and calculating the total dissolved solids in your drinking water will define its quality.
Total Dissolved Solids, or TDS, are inorganic compounds found in water, such as salts, heavy metals, and some traces of organic compounds dissolved in water.
Simply, it represents the total concentration of dissolved substances in water. The inorganic salt commonly found in TDS is categorized into (1) cations, which include calcium, magnesium, potassium, and sodium, and (2) anions, which include carbonates, nitrates, bicarbonates, chlorides, and sulfates.
As such, cations are positively charged ions, and anions are negatively charged ions.
Some of these compounds or substances can be essential in life, including the organic matter that is sometimes naturally present in water and the environment.
The TDS level is a good indicator of whether drinking water is suitable for human consumption. It also tests whether a certain water quality requires a rigid filtration system or is highly contaminated.
However, it can be harmful when consumed more than the body needs. Total dissolved solids in water are among the leading causes of turbidity and sediment in drinking water.
When left unfiltered, total dissolved solids can cause various diseases.
Total dissolved solids (TDS) measure the combined total of organic and inorganic substances in a liquid. This includes anything present in water other than the pure H20 molecules.
These solids are primarily minerals, salts, and organic matter that can generally indicate water quality.
In this article, we'll discuss TDS in Drinking water, TDS meters, the composition of TDS (and how it contaminates water quality), and the reasons why TDS ends up in dissolved water.
We will also discuss the acceptable TDS level in drinking water, factors affecting TDS, and several treatments and mitigation processes to employ to lessen the negative effects of TDS in water.
Understanding the Total Dissolved Solids (TDS)
All natural water sources contain dissolved substances and minerals, measured as total dissolved solids (TDS). Natural minerals are inorganic salts.
Some are potassium, calcium, magnesium, chlorides, bicarbonates, and sulfates. In addition, it can contain low-concentration contaminants like heavy metals.
When you measure the TDS, the presence of heavy metals cannot be exactly determined.
TDS is identified as parts per million (ppm) or mg/L in the water. The EPA has not identified a TDS limit since TDS does not risk people's health. However, it suggests that the drinking water only has a level of up to 500 ppm.
If the water is above 500 ppm, they can notice deposits on the water, salty taste, or staining. These effects are not harmful. However, it can be noticeable.
The TDS in Drinking Water
The TDS in drinking water comes from natural sources, sewage, urban runoff, industrial wastewater chemicals used in the water treatment process, and the hardware or piping used to distribute water.
In the US, natural environmental features, such as salt deposits, mineral springs, seawater intrusion, and carbonate deposits, have caused higher TDS.
Other sources may include anti-skid materials, salts used for road de-icing, stormwater, agricultural runoff, water treatment chemicals, and point/non-point wastewater discharges.
Generally, the total dissolved solid concentration is the total cations (positively charged) and anions (negatively charged) in the water. Thus, the total dissolved solids test qualitatively measures the number of dissolved ions but does not tell us the nature or ion relationships.
In addition, the test does not provide insight into the specific water quality issues, such as Elevated Hardness (mineral content in water), Salty Taste, or Corrosiveness (also called aggressive water, which is how water dissolves with other materials).
Therefore, the total dissolved solids test is used as an indicator test to determine the general quality of the water. The sources of total dissolved solids can include all of the dissolved cations and anions.
Still, the following table can be used to generalize the relationship of TDS to water quality problems.
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Cations combined with Carbonates. |
Associated with hardness, scale formation, bitter taste |
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Cations combined with Chloride |
A salty or brackish taste increases corrosivity |
Total Dissolved Solids (TDS) Meters
Many people are aware of TDS meters. These meters measure the water’s electrical conductivity, which can be related to the amount of TDS.
Meanwhile, a TDS meter cannot directly measure heavy metal contaminants like arsenic and lead. It does not indicate whether the water filter works properly to decrease this contaminant.
The normal TDS level ranges from 50 ppm to 1,000 ppm. On the other hand, the National Sanitary Foundation (NSF) International does not certify using the TDS meters.
What Composes Total Dissolved Solids and How Do They Contaminate Our Water Supply?
The total dissolved solids in drinking water comprise different substances. Bacteria and viruses, organic compounds found in drinking water, are part of the natural flora of water and the environment.
Chemicals in the water and water supply include heavy metals, salts, and pharmaceutical drugs caused by human waste materials, contaminating the water and water supply.
Water from springs, lakes, and waterfalls has natural microorganisms and salts. This will, in turn, go to public water treatment and be stored for the community's supply.
Also, phytoplankton, one of the natural floras of water, can sometimes be found. Phytoplankton is a microscopic plant that drifts off to different bodies of water.
Sometimes, chemicals such as iron, potassium, sodium, and other chemicals known to man are present in drinking water. These chemicals are caused by human waste products that contaminate these water sources.
The volatile organic compounds also pollute the water by leaking through the water supply by soil.
Volatile organic compounds, also known as VOCs, are rapidly evaporating compounds chemically designed for specific use at home, school, and anywhere.
Other Reasons Why Solids End Up Dissolved in Water
Mineral springs contain high levels of dissolved solids because the water flows through a region with high-salt rocks.
For instance, the Prairie provinces in the US tend to have high levels of dissolved solids because the ground contains high amounts of calcium and magnesium.
These minerals can also come from human activities. Agricultural and urban runoff, such as wastewater discharges, industrial wastewater, and salt used to de-ice roads, can carry excess minerals into water sources.
What is the Acceptable Total Dissolved Solids (TDS) Level in Drinking Water
Total Dissolved Solids (TDS) are measured in milligrams per unit volume of water (mg/L) and are also referred to as parts per million (ppm). The EPA has set the maximum concentration level for drinking water at 500 mg/L.
Factors Affecting TDS
High Flow Rates
The flow rate of a body of water can be a major factor in TDS concentrations. Fast-running water can contain more sediment. Heavy rains can also pick up clay, sand, silt, and other particles, such as tire particles, leaves, and soil.
Moreover, a change in the flow rate can affect total suspended solids. If the current water's direction or speed increases, the particulate substance from the bottom sediments may be suspended.
Soil Erosion
Soil erosion is caused by troubles on the surface of the land, such as illegal logging, forest fires, mining, and construction. Eroded soil particles can be carried into surface water via stormwater, increasing the level of TDS and TSS in the water.
Urban Runoff
When a storm comes, debris and solid particles from commercial or residential areas can be washed away into streams, due to the large amount of pavement in cities, infiltration and velocity increase. The natural settling areas are removed. The storm also carries sediments into rivers and creeks.
Overflow of the Septic and Wastewater System
Particles from wastewater treatment plants can also contribute to the suspension of solids in the stream. Residential wastewater contains human waste, food residue, and other materials we flush into the drains.
Most of the solids in the plant's water have already been eliminated. However, not everything is eliminated during the treatment.
Rotting Animals and Plants
As animals and plants decay, suspended organic particles can be released, contributing to the concentration of TDS and TSS in drinking water.
Bottom-Feeding Fish
Bottom-feeding fish like carp can disturb the sediments since they tend to remove vegetation. Indeed, these sediments can add to TDS and TSS.
Why Should You Measure the TDS Levels in Your Water?
Numerous water supplies exceed this level. TDS levels exceeding 1000mg/L are generally considered unfit for human consumption. A high level of TDS indicates potential concerns and calls for further investigation.
Potassium, chlorides, and sodium most often cause high levels of TDS. These ions have little or no short-term effects, but toxic ions (lead, arsenic, cadmium, nitrate, and others) may also dissolve in the water.
Even the best water purification systems require monitoring for TDS to ensure that the filters and membranes effectively remove unwanted particles and bacteria from the water.
Here are other applications of the importance of the TDS level:
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Taste / Health
High TDS would result in an undesirable taste, which could be salty, bitter, or metallic. The EPA’s recommended maximum level of TDS in water is 500mg/L (500ppm).
Health Considerations
In past studies, inverse relationships were reported in TDS concentrations on drinking water and coronary heart disease, cancer, cardiovascular heart disease, and arteriosclerotic heart disease. There is an inverse correlation between TDS levels and total mortality rates.
An Australian study found that mortality rates are higher in communities with higher levels of soluble calcium, sulfate, magnesium, chloride, and fluoride than in communities with lower levels.
Other Considerations
The dissolved solids present in the water can affect its taste.
In a study, a panel of tasters rated the palatability of drinking water. The water tastes excellent if the TDS is less than 300 mg/L, good if it is between 300 and 600 mg/L, fair if it is between 600 and 900 mg/L, poor if it is between 900 and 1,200 mg/L, and unacceptable if it exceeds 1,200 mg/L.
If the water has a shallow TDS level, its bland, flat taste can also make it unacceptable.
Apart from the water’s palatability, some components of TDS can affect the encrustation and corrosion of the water distribution systems.
Examples are sulfates, chlorides, calcium, carbonates, and magnesium. High TDS levels above 500 mg/L can result in excessive scaling in the water heater, boilers, pipes, and other appliances inside the house. With scaling, it can shorten the lifespan of your appliances.
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Filter performance
Test your water to ensure the reverse osmosis or other water filter or water purification system has a high rejection rate and know when to change your filter (or membrane) cartridges.
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Hardness (and Water Softeners)
High TDS point out the Hard water, which causes scale build-up in pipes and valves. This eventually restricts performance.
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Aquariums / Aquaculture
Aquatic life needs a constant mineral level. The water in an aquarium or tank must have the same TDS levels and pH as the fish and reef’s original habitat.
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Hydroponics
TDS is the best measurement of the nutrient concentration in a hydroponic solution.
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Pools and Spas
TDS levels must be monitored to prevent maintenance problems
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Commercial / Industrial
High TDS levels could prevent the functions of certain applications, such as boilers and cooling towers, food and water production, etc.
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Colloidal silver water
TDS levels must be controlled before making colloidal silver.
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Coffee and Food Service
For a truly great cup of coffee, proper TDS levels must be maintained.
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Car Washing and Window Cleaning
It gives the best result when cleaning.
Options for the Treatment of TDS
NSF International has published a certified reverse osmosis system that can reduce the TDS level in the water. This can be extremely helpful as you identify the suitable unit to install in your house.
Indeed, NSF International does not approve of the use of TDS meters. However, it does certify treatment systems that reduce contaminants like heavy metals.
The system must effectively reduce the contaminants claimed by the manufacturers. It must also have structural integrity to ensure the treatment system or filter does not leak.
Material safety testing also ensures the filter can identify and eliminate impurities when unused.
Finally, the product must be labeled accurately to ensure it does not contain misleading information.
Analytical Methods and Treatment Technology
The most commonly used analysis method in water supplies is measuring specific conductivity, which determines the presence of ions in water. A factor determining the water type converts these measurements to TDS values.
Conventional water treatment techniques do not effectively remove TDS. The chemicals added during this process can generally increase the concentration of the TDS.
Some treatment techniques, like softening through lime-soda ash plus sodium exchange zeolite, can increase TDS concentration. A demineralization process is needed for TDS removal.
Indeed, demineralization is available to decrease the TDS levels, but its high cost can be a major constraint. Electrodialysis and reverse osmosis can be economical methods to remove TDS in public water supplies.
What are the Ways to Remove Total Dissolved Solids in Drinking Water?
The soils absorb these chemicals, eventually contaminating the water supplies. Though some total dissolved solids are natural flora, filtration, and purification effectively remove these chemicals from our drinking water.
To give you a short water filtration and purification process, the water coming from the water sources goes to the public water treatment to undergo filtering. Large particles or substances are filtered out and removed from the water.
Small particles can sometimes pass through the filters during this process, causing turbidity in drinking water, which is unsafe to consume. Once it undergoes filtration, it is purified using certain methods.
Depending on the company or water treatment facility, some remove microscopic particles from water using chemicals, radiation, microfiltration, or chlorination.
Removing dissolved solids in drinking water using chemicals as reagents, these reagents help filter these substances out. Chemicals such as aluminum sulfate and liquid chlorine are used.
These chemicals are flocculating chemicals that help filter water. They clump particles together until they form a larger particle.
These flocks can then be easily removed or filtered out. Some chemicals used are fluorosilicic acid, sodium silicofluoride, and sodium fluoride, which produce a unique reaction.
These chemicals create heat and give off energy. When combined with water, they burn, killing bacteria, viruses, protozoans, and other organic microorganisms.
Once the drinking water is filtered out of impurities, it tastes strange and is not drinkable. This is when calcium hydroxide is added to it.
Calcium hydroxide, or lime water, is an automated chemical that does not affect alkalinity and water acidity. So it is safe to drink and tastes like natural water.
While some water treatment facilities use chemical reagents to filter and purify drinking water, some public facilities use filtration, chlorination, and UltraViolet radiation.
This treatment starts when water from sources goes to the water supply to filter particles. Once filtered, it will remain in the water supply for chlorination.
When added, chlorine remains in the water storage until the smell of chlorine cannot be detected.
Since chlorine is a derivative of salt and sodium, it can sometimes not be easily dissolved. When the chlorination process is complete, it undergoes a special radiation process.
With the help of ultraviolet rays, water is then radiated to ensure that the remaining chlorine substances will be dissolved and that the microorganisms that made it through the filtration and chlorination process are killed.
These residues turn into sediments found at the bottom of the water and cause turbidity in the water.
The Correlation Between pH Levels and TDS Levels
Total Dissolved Solids (TDS) correlate positively with conductivity and affect pH. Thus, the higher the TDS, the higher the conductivity and the lower the pH toward acidity.
Furthermore, the taste of the water may change in the presence of dissolved solids. By standard, surface water has a pH value between 6.5 and 8.5, while groundwater typically has a pH between 6.0 and 8.5. However, the water source can still differ from one source to another.
There are a lot of human-induced activities that pose huge threats to the pH levels of the water sources within the vicinity.
In particular, industrial operations and vehicles release harmful substances such as sulfur dioxide and nitrogen oxides, which produce acid rain and, in turn, affect the overall pH levels of nearby water sources.
Another factor is chemical pollution, which can transform a large body of water into acid. Harmful chemicals can diffuse into the water through illegal discharges or irresponsible wastewater treatment processes.
Ultimately, altering the pH levels in water can have several consequences—good or bad. For example, acidification can put living things, including plants and animals, in dangerous (sometimes lethal) situations.
Moreover, marine and aquatic life are also in extreme danger. They are very sensitive to changes in water temperature and composition, which can, in particular, affect the food supply and biodiversity of marine life.
Guidelines for pH: Canada Vs. United States
CANADA
The water pH level guidelines vary from city to city and country to country. In Canada, the pH of drinking water should be between 7.0 and 10.5, according to the Canadian Guidelines for Drinking Water Quality.
Meanwhile, Saskatchewan, a province in Canada, has its pH level guidelines. According to the Saskatchewan Drinking Water Standards and Objectives, the pH of drinking water should be between 6.5 and 9.0.
UNITED STATES
PH is the next water standard in the United States, after TDS. Following the Secondary Maximum Contaminant Level, pH levels should range between 6.5 and 8.5.
Moreover, the Environmental Protection Agency has stated that a pH level of less than 6.5 has noticeable effects. This pH level denotes a bitter-tasting and metallic aftertaste in water.
Likewise, a pH of 8.5 generates noticeable effects such as slippery texture, soda-like taste, and small deposits.
Conclusion
TDS is an essential factor in the water quality of drinking water. It indicates whether the water is too turbid or lacks the essential minerals the body needs. An elevated total dissolved concentration (TDS) level does not mean the water becomes a health hazard. But this doesn't mean the water may have aesthetic problems or cause nuisance problems.
The problems may be concerned with staining, taste, or precipitation. Higher TDS levels may indicate trace metals are in the water. Another important thing to remember is that the water may be corrosive if the TDS level is very low.
Corsive waters may leak toxic metals from household plumbing. Given this situation, it may pose a health hazard as well. Dealing with this kind of water, such as hard water, can be annoying.
The initial recommendation is to get your water tested and determine your water's general quality and chemistry. Do this before consuming or installing your water treatment system.
To conclude, ensuring drinking water quality is clean, safe, and reliable should be a basic standard. TDS, among other factors, can determine whether or not our water source is fit for daily consumption.
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