What is TDS? How It Affects Water Purifier Performance

If you use an RO water purifier at home, you’ve probably heard the term TDS many times. But what exactly does TDS mean? And why is it so important for choosing the right water purifier and maintaining its performance?
In this article, we break it down in simple, practical language.

What is TDS?

TDS stands for Total Dissolved Solids.
It refers to the total amount of organic and inorganic substances dissolved in water, including:

• Minerals
  
• Salts
  
• Metals
  
• Ions
  
• Chemicals
  

TDS is measured in ppm (parts per million) or mg/L.

What contributes to TDS in water?

Common sources include:

• Natural minerals (calcium, magnesium, potassium)
  
• Industrial waste or chemicals
  
• Agricultural runoff (fertilizers, pesticides)
  
• Rust and metal pipes
  
• Sewage contamination
  

Not all TDS is harmful. Some minerals in water are actually good for health — but too much can be dangerous.

Ideal TDS Level for Drinking Water

According to WHO & BIS standards, the acceptable TDS for drinking water is up to 500 ppm.

How Does TDS Affect Your RO Water Purifier?

1. Determines whether you need RO purification

RO (Reverse Osmosis) purifiers are mainly used when TDS is above 250–300 ppm.

• If TDS is low, RO may remove too many essential minerals.
  
• If TDS is high, RO is necessary to remove harmful salts, metals, and contaminants.
  

2. Affects filter lifespan

Higher TDS leads to:

• Faster clogging of sediment & carbon filters
  
• More pressure on RO membrane
  
• Reduced overall purifier lifespan
  

This means more frequent filter replacements.

3. Impacts taste and odor

Water with high TDS may:

• Taste salty
  
• Taste bitter
  
• Have an unusual smell
  
• Leave white scaling on utensils
  

Your RO purifier corrects this, but with very high TDS, the purifier may struggle.

4. Affects purifier performance & output

High TDS impacts:

• Purification efficiency
  
• Water flow rate
  
• Wastewater ratio
  
• Purity of final drinking water
  

Water with extremely high TDS (>1000 ppm) may require pre-treatment or additional purification stages.

Symptoms of High TDS in Water

You may be dealing with high TDS if you notice:

• White scaling on taps, kettles, or utensils
  
• Bad taste or smell in water
  
• Skin dryness after bathing
  
• Reduced soap lather (hard water)
  
• Early failure of home appliances like geysers and washing machines
  

In such cases, an RO purifier becomes essential.

How to Check TDS at Home

You can measure TDS using:

1. Digital TDS Meter (fast & accurate)
   
2. Water test kits
   
3. Professional water testing services
   

For best purifier performance, check TDS every 3–6 months.

How RO Purifiers Control TDS

Reverse Osmosis works by pushing water through

How RO Purifiers Control TDS

Reverse Osmosis purifiers work by pushing water through a semi-permeable membrane.
This membrane blocks:

• Excess salts
  
• Heavy metals
  
• Harmful chemicals
  
• Microorganisms
  
• Dissolved impurities
  

Only pure water molecules pass through, reducing TDS to safe levels.

Most modern RO purifiers also include:

• Sediment Filter – removes dust, dirt, and sand
  
• Carbon Filter – removes chlorine, smell, and organic impurities
  
• RO Membrane – reduces high TDS
  
• UF / UV Stages – adds extra purification
  
• TDS Controller / Mineralizer – restores essential minerals
  

This combination maintains taste while keeping water safe.

Why TDS Controller or Mineralizer is Important

When RO filtration reduces TDS too much (below 70 ppm), the water may lose essential minerals like calcium & magnesium.
That’s why many purifiers come with:

1. TDS Controller

It mixes a small amount of raw water (after pre-filters) with RO-filtered water.
This keeps mineral balance stable.

2. Mineralizer / Alkaline Filter

It adds back beneficial minerals to improve taste and pH level.

These are essential if your water source is borewell or has naturally low TDS.

What Happens if TDS is Too Low?

Very low TDS (<50 ppm) may result in:

• Flat or tasteless water
  
• Lack of essential minerals
  
• Possible long-term health impact (mineral deficiency)
  

If your raw water TDS is already low, consider:

• UV + UF purifier instead of RO
  
• Using RO with a strong mineralizer
  

How TDS Affects Your Health

High TDS water may cause:

• Indigestion
  
• Kidney stones
  
• High salt intake
  
• Metallic taste
  
• Heart-related risks (due to sodium)
  

Low TDS water may cause:

• Mineral deficiency
  
• Weak taste
  
• Poor hydration efficiency
  

Maintaining the right balance is key.

Best TDS Range for RO Purifier Output

After purification, the ideal TDS should be:

• Between 75–150 ppm for drinking
  
• Up to 200 ppm if you prefer slightly mineral-rich water
  

Anything below 50 ppm is too low, and above 300 ppm may not be ideal.

When You Should Get Professional TDS Testing

You should get a technician to inspect your water if:

• Water tastes salty or bitter
  
• Filters are clogging too fast
  
• RO output has reduced
  
• Water flow is slow
  
• White scaling is visible on utensils
  
• TDS levels fluctuate frequently
  

Regular 6-month maintenance ensures your purifier works efficiently.

Tips to Maintain Ideal TDS Levels at Home

• Check TDS every 2–3 months
  
• Replace filters on time
  
• Clean and sanitize the RO storage tank
  
• Use a pre-filter for borewell water
  
• Never skip annual RO membrane inspection
  
• Install a mineralizer if water tastes too low-TDS
  

Good maintenance ensures healthier, better-tasting water.

Conclusion

TDS plays a crucial role in your water quality and the performance of your RO purifier.
Understanding TDS helps you:

• Choose the right water purifier
  
• Maintain your purifier properly
  
• Ensure safe and healthy drinking water
  
• Avoid unnecessary repairs
  

If your water has high or fluctuating TDS, getting professional servicing is the best way to keep your purifier working efficiently.