How To Reduce TDS Of Water?

Reverse osmosis is still a very good and popular way to reduce TDS, but there are many alternatives that might be better for your particular evil plan! Familiarizing yourself with the range of options—everything from tried and true methods such as distillation and ion exchange to more novel techniques like capacitive deionization—will allow you to better understand your water quality management needs.

Water is the essence of health, household, and for many industries. But in reality, water usually has dissolved substances impacting its quality, taste, and usability. This is significant in the event of TDS (Total Dissolved Solids), which can be abbreviated to refer to many other substances, and it is often required to remove the TDS from the water, as it has a major role to play in how good the quality of water will be. 

Although reverse osmosis (RO) is the most popular option for reducing TDS levels, there are many alternative options that may serve better in specific cases, or when RO is not feasible.

This guide will help break down what TDS is, why it matters, and the wide range of TDS reduction methods available, from RO-based solutions to non-RO-based solutions. So, if you are worried about your drinking water quality, keeping your appliances safe or if you need TDS level low for some industrial purposes, let us guide you to understand your options to bring TDS level down.

What is Total Dissolved Solids (TDS)

Total Dissolved Solids (TDS) is the measure of the combined content of all inorganic and organic substances in water that could be dissolved into water and can pass through (a filter with a 2-Micrometer pore size).

These substances include:

• Minerals: Including calcium, magnesium, potassium, and sodium.
• Salts: Mainly chlorides, sulfates and bicarbonates.
• Metals: Copper, lead, manganese, iron, and others.
• Organic matter: Matter made from dead plants and animals.
• Chemical compounds: Including both natural sources and from human activities.

How Is TDS Measured?

Total dissolved solids (TDS) is expressed typically in parts per million (ppm) or milligrams per liter (mg/L), being the two measures equivalent. 

As a point of reference, the United States Environmental Protection Agency (EPA) recommends no more than 500 ppm of TDS in drinking water (as a secondary standard, however, meaning it’s based on aesthetics not health).

Sources Of TDS In Water

Water can have TDS from many sources:

• Natural geological formations: Water moves through rock and soil, dissolving minerals and carrying them in solution.
• Agricultural runoff: Fertilizers, pesticides, and soil amendments can release dissolved solids.
• Urban runoff: Chemicals used on roadways, construction materials, and products used in the landscaping add to TDS.
• Wastewater releases: Industrial processes and sewage treatment can emit dissolved matter.
• Chemicals used to treat water: As strange as it sounds, some chemicals that have been used to treat water for other impurities actually raise TDS.
• Seawater encroachment: Saltwater can intrude into freshwater coastal areas.
• Road salt: In areas where roads are salted in the winter, runoff can dramatically increase TDS.

Why TDS Matters

The implications of TDS are more far-reaching than matters of water purity:

Effects Of Tough Water Quality And Usage

• Taste and odor: Water with high TDS can give a bitter, salty, or metallic taste and adversely affect beverages and food preparation.

• Look for: High total dissolved solids (TDS) can make your water appear cloudy or murky.
• Equipment performance: Limescale buildup from mineral deposits can corrode appliances such as water heaters, coffee makers and ice machines.
• Plumbing integrity: Some dissolved solids can promote accelerated corrosion in piping and fixtures.
• Energy efficiency: High TDS scale buildup reduces thermal efficiency of heating elements.

Specific Industry Concerns

• Food and beverage establishments: TDS can influence flavors and product uniformity.
• Healthcare: Certain medical equipment which requires low TDS water. 
• Manufacturing: Controlled water quality is critical in many precision manufacturing processes.
• Laboratories: Scientific research requires ultra-pure water.
• Agriculture: High total dissolved solids (TDS) in irrigation water can affect both soil health and crop productivity.

Reducing TDS With Reverse Osmosis (RO)

Reverse osmosis is still one of the most effective and commonly used methods to remove TDS. Having insights on how it operates offers perspective on what other ways could look like.

How RO Works

In reverse osmosis, a semipermeable membrane with very small pores (0.0001 micron) allows water molecules and only a limited number of dissolved solutes to pass through due to the pressure difference. 

This requires exerting pressure to exceed the natural osmotic pressure, driving the water in the opposite direction through the membrane.

Advantages of RO Systems

• High efficiency: Can remove 95-99% of TDS.
• Stable performance: When adequately maintained, the outcome are quite consistent.
• Scalability: Offers from under-sink devices to industrial-scale systems
• Often eliminates other contaminants as bacteria, viruses, and many chemicals.

Limitations of RO

• Water waste: Traditional systems waste 2–4 gallons of water per 1 gallon of filtered water.
• Mineral removal: Removes beneficial minerals, which are responsible for the taste of the water.
• Consumer needs: Needs be pressurized (electricity in most installations).
• Maintenance requirements: Membranes need to be replaced regularly.
• Hidden Expenses: Not the cheapest option up front.
• Slow water production: Residential systems typically produce water at a very slow pace.

How to Reduce TDS Without Reverse Osmosis (RO)?

If you are looking for options to the RO, either because of its constraints, the demands of an application, or simply the desire to know all possible routes—there are several approaches that can be utilized.

Distillation

Distillation is one of the oldest methods of purifying water, imitating nature’s hydrologic cycle.

Process Overview

Liquid water is turned to vapor, as it is brought to its boiling point. This vapor ascends, leaving behind the dissolved solids, before it is passed to a separate container and condensed back into liquid form. 

The process is highly effective at distilling water from almost any dissolved substances.

Advantages

• Very efficient: Can eliminate 99.9% of TDS
• Keeps it simple: Built on fundamental physical laws
• Multipollutant removal: Effective against microorganisms and many volatile organic compounds as well
• No filter change: No membranes and filter replacement required

Limitations

• Heat demanding: Needs lots of thermal energy
• Slow process: Water is produced at/for relatively low rates
• Removal of healthy minerals: Removes all minerals from water
• Volatile compounds : Certain volatile organic compounds might be transferred with the steam
• Microbes that survive heat: Some microorganisms can withstand the process

Distillation systems vary from basic countertop units to advanced automated systems. They are especially prized in applications where high-purity water is needed, where concerns over energy costs or speed of production are not paramount.

Ion Exchange Process: Deionization (DI)

While deionization employs specialized ion exchange resins to remove ionized minerals and salts in an exchange manner.

Process Overview

There are two resin bead types typically used in DI systems:

• Cation exchange resins: Substitute positive ions (e.g., calcium and magnesium) for hydrogen ions
• Anion exchange resins: Bind (negative ions) both chloride and sulfate replace them with hydroxide ions

The hydrogen and hydroxide ions then react to create pure water (H₂O).

Advantages

• High purity results: Very low TDS levels (often below 10 ppm)
• Water waste: None, uses virtually all input water unlike RO
• Speedy treatment: Can treat water at a relatively fast rate
• No running desire: Depends on water pressure in most orientations
• Sensitive to certain ions: Can detect ions of concern

Limitations

• Finite capacity: Resins get spent and need to be regenerated or replaced
• Chemical regeneration: Regeneration of resins involves both acids and bases
• Poor removal of non-ionized substances: Not as effective for organics
• TDS condensation: TDS drawbacks in high-TDS water: High mineral content rapidly depletes resin capacity
• pH: pH of the outgoing water is not stable

Deionization is particularly useful in laboratory, electronics manufacturing, and aquarium keeping where specific ion control is very important.

Water Softening By Ion Exchange

Water softeners aid concentration of TDS in the water by addressing dissolved calcium and magnesium ions, which are often responsible for elevated TDS levels.

Process Overview

Ion exchange water softeners use resin beads that are charged with sodium ions. When water moves through the resin bed, hardness minerals (calcium and magnesium) are attracted to the resin and sodium ions are released in exchange. Saltwater (sodium chloride) is periodically used to regenerate the system.

Advantages

• Efficient hardness removal: Eliminates scale-forming calcium and magnesium
• Equipment protection: Stops scale buildup in pipes and appliances
• Easy upkeep: Only needs infrequent salt updates
• Proven stability: An end-user tested technology with 30 years maturation
• Inexpensive: Fairly low-cost to buy and run

Limitations

• Only lowers TDS concentration: Just selectively exchanging different ions, instead of eliminating them
• Adding sodium: Adds sodium to the water
• Used Salt: Salt is consumed and brine is released during deferring
• Ecosystem impact: Salt discharge can disrupt local water ecosystems
• Water softeners are restricted in some areas for salt discharge concerns

Water softening provided that hardness minerals are the principal TDS concern is particularly valuable in terms of appliance protection and soap improvement.

Capacitive Deionization (CDI)

Capacitive deionization is a more recent TDS reduction method that uses electrical rather than chemical exchangers or physical barriers.

Process Overview

In CDI systems, an electrical potential is applied across electrodes to form an electric field, which attracts and retains charged ions from the water flowing through the electrodes. Ions build up on the electrode surfaces, resulting in water with a lower TDS. Every so often, the polarity is switched to clear the electrodes and wash away the captured ions.

Advantages

• Energy saving: Consumes less energy than RO or Distillation
• Water waste relative to RO: Low water recovery
• No chemicals needed: No chemical regenerants are used
• Selective ion stripping: Can possibly be tuned to target only certain ions
• Powerful technology: Not limited to larger applications

Limitations

• Emerging tech: Fewer methods have been developed
• Upfront cost: Currently pricier than some other options
• Poor removal of neutral species
• TDS levels and prevention of reverse osmosis: Most effective with a lower initial TDS level
• Require sophisticated electronic controls

CDI technology is being adopted in some niche industrial uses and has the potential to go more mainstream as prices fall and abilities rise.

Adsorption Methods

Different adsorption media can decrease particular constituents of TDS via the attraction of dissolved species to their surfaces.

Common Adsorption Media

• Activated alumina: Ideal for fluoride and arsenic
• Bone char: A standard medium for defluoridation
• Ion-selective resins: Created to capture specific ions in solution
• Seoliter: Natural or synthetic aluminosilicate deposit capable of ion-exchange
• Iron-containing media: For arsenic, hydrogen sulfide, and metals
• Granular ferric hydroxide: Specifically engineered for arsenic removal

Advantages Of Adsorption

• Selective removal: Very selective for certain problematic contaminants
• Ease of use: Provides most systems with a range of activity
• No electricity needed: Most rely on water pressure alone
• Moderate price: Typically less expensive than complex TDS reduction systems
• Perfect for situations where you need to fix something specific about TDS

Limitations Of Adsorption

• Facility-scale granulation and slime: Each media typically only target specific contaminations
• Capacity limitations: Media are eventually saturated and need replacement
• Different ions: Interference from other dissolved substances can cause performance to decrease
• pH sensitivity: A lot of adsorption media work best in limited pH ranges 
• Minimal total TDS removal: Not practical for total TDS reduction

Adsorption technologies perhaps perform best in niche situations where a small number of troublesome, dissolved contaminants cause disproportionate problems.

Precipitation

This process involves chemical precipitation to form insoluble particles in solution, so filtering could remove them.

Process Overview

In general, chemical agents are added to water so that they react with the targeted dissolved elements and make bigger particles (precipitates) which can be removed through simple filtration.

Lime, soda ash, and ferric chloride are common precipitating agents.

Advantages

• Highly effective: Can treat low, medium, and very high TDS levels
• Targeted removal: What you can remove, removals can focused more specifically on problem components
• Industrial scalability appropriate for large scale applications
• Compatibility with existing systems (often used as pre-treatment for additional methods)
• It can adjust to changes in water quality

Limitations

• Requires continual delivery of chemical supplies
• Sludge generation: Produces solid waste that needs to be disposed
• Requires technical knowledge: Has to do with appropriate chemical dosing and monitoring
• Less applicable to residential setting: Used predominantly, in industrial scenarios
• Post precipitation filtration: Often requires secondary treatment

Chemical precipitation is most frequently used in industrial water treatment, municipal systems, and specialized applications such as heavy metal removal.

Monitoring TDS Levels

Whether you use a TDS reduction system or a RO system to reduce TDS levels, monitoring your water quality is critical to ensure that the system is working and the water quality you’re making is optimal.

TDS Measurement Tools

TDS can be measured by several tools:

• Digital TDS meters: These are portabe devices that give instant readings
• Conductivity meters: They measure the electrical conductivity, which is directly proportional to TDS
• Mineral content: Professional water testing through laboratory evaluation
• TDS test strips: Easy-to-use, color-change indicators for rough measurements

Factors To Consider For TDS Reduction

Factors to bear in mind when choosing a TDS reduction process:

• Target TDS level 
• Required purity for intended use
• Daily required treated water
• Upfront and continued operating expenses
• Space availability
• Physical footprint to install equipment
• Energy consumption, waste of water, and chemical emissions
• Actual need and time frame
• Local restrictions on specific technologies
• Compatibility with existing water Treatment
• Anticipated equipment lifetime and functional stability

Summing Up, How To Reduce TDS Of Water

It’s more than just a straightforward scaling solution; TDS reduction from water is then not just a piece of equipment that you install for the job. TDS reduction requires knowing what your unique water quality issues are, what technologies best address those issues, and employing appropriate monitoring and maintenance systems.

If you would like to speak to a quality expert to determine what solution is best for you while ensuring the most effective results with little waste, energy consumption, and long-term costs, or you would like to learn about the different water quality monitoring kits we offer, do not hesitate to reach out to the world-class team at Atlas Scientific.