NGT Guidelines on RO & TDS 2026: Why You Should Avoid RO in Low TDS Water

Having drinking water is very important for our health. That is why many people in India buy water purifiers to get clean drinking water at home. A lot of homes have reverse osmosis water purifiers, which are very popular.. Many people buy these water purifiers without checking if they really need them.

People think that reverse osmosis water purifiers are good for home use. First you should check if your home really needs one. Many homes already have tap water so you should check the water quality at your home before buying a reverse osmosis water purifier. There are some reverse osmosis water purifiers but some can be very expensive to install and use so you need to think about how much you will spend on the water purifier and how much it will cost to maintain it over time.

If you live in an area where the water's not good then you should think about getting a reverse osmosis water purifier because it can give you safe and clean drinking water. It is up to you to decide if you want to buy a reverse osmosis water purifier or not. Remember that your choice can have consequences. You can avoid making a mistake by doing some research before you make a decision, on reverse osmosis water purifiers.

The National Green Tribunal (NGT) has raised serious concerns regarding the misuse of RO systems, especially in areas where water quality is already safe. According to the NGT, using RO unnecessarily can harm both human health and the environment.

This detailed guide will help you understand everything about RO, TDS, NGT rules, health impacts, and how to choose the right water purifier.

What is Reverse Osmosis (RO)?

Reverse Osmosis (RO) is an advanced water purification technology that uses a semi-permeable membrane to remove dissolved impurities from water. The process forces water through a membrane that blocks contaminants and allows only clean water to pass.

• Removes heavy metals like lead and arsenic
• Eliminates dissolved salts
• Improves taste and clarity
• Removes harmful contaminants

While RO is effective, it also removes essential minerals such as calcium and magnesium, which are important for health.

What is TDS (Total Dissolved Solids)?

Total Dissolved Solids (TDS) is a measure of all dissolved substances in water, including minerals, salts, and organic matter. It is an important indicator of water quality.

• Measured in mg/L or ppm
• Includes calcium, magnesium, sodium
• Determines taste and safety of water

Ideal TDS Levels for Drinking Water

TDS Level (mg/L)	Water Quality
50–150	Excellent
150–300	Good
300–500	Acceptable
Below 50	Too low
Above 500	Needs purification

NGT Guidelines on RO Usage

The National Green Tribunal says RO purifiers should not be used if TDS levels are low, below 500 mg/L. This rule is to stop wasting water and keep minerals in drinking water. The National Green Tribunal made this rule to help. We should follow it for drinking water.

Why NGT Restricted RO Systems?

1. Loss of Essential Minerals

Reverse Osmosis removes minerals like calcium and magnesium. Calcium and magnesium are necessary, for bones, proper heart function and overall health of the Reverse Osmosis user. The Reverse Osmosis system takes out these minerals. We need calcium and magnesium for our bodies to be healthy. The Reverse Osmosis water does not have these minerals because it removes them.

2. Water Wastage

RO systems waste a significant amount of water. For every 1 liter of purified water, approximately 2–3 liters are discarded.

3. Environmental Damage

Excessive use of RO systems contributes to water scarcity and increases wastewater discharge, which negatively impacts the environment.

Health Effects of Low TDS Water

Drinking water with very low TDS can lead to several health issues:

• Mineral deficiency
• Weak bones
• Electrolyte imbalance
• Fatigue and reduced immunity

Water is not just for hydration—it is also a source of essential minerals.

When Should You Use RO?

• When TDS is above 500 mg/L
• When water contains heavy metals
• When borewell water is highly saline

When Should You Avoid RO?

• When TDS is below 500 mg/L
• When water is already safe
• When mineral content is sufficient

How to Check TDS at Home?

You can measure TDS using a digital TDS meter. It is affordable, easy to use, and gives instant results.

Alternatives to RO

UV Purifiers

Kill bacteria and viruses while retaining minerals.

UF Purifiers

Remove impurities without stripping minerals.

Boiling

Traditional and effective method for killing pathogens.

Common Myths About RO

• RO water is always best – False
• Lower TDS is healthier – False
• Everyone needs RO – False

Real-Life Example

If a household has a TDS level of 150 mg/L and still uses RO, it will remove beneficial minerals and waste water unnecessarily. In such cases, UV or UF systems are better choices.

Conclusion

RO water purifiers are powerful but not always necessary. Using them blindly can lead to health issues and environmental harm. The NGT emphasizes using RO only when required.

Always test your water, understand TDS levels, and choose the right purification method.

FAQs

What is the ideal TDS level for drinking water?

50–300 mg/L is ideal.

Is RO water safe?

Only if TDS is high.

Why does RO waste water?

Due to filtration process.

Can low TDS water be harmful?

Yes, it lacks minerals.

When should I use RO?

When TDS exceeds 500 mg/L.