Do You Really Need an RO Water Purifier?

The RO Hype

Walk into any electronics store in India and the salesperson will likely push an RO purifier. But RO is expensive, wastes water, removes beneficial minerals, and requires maintenance. For many Indian homes, it is simply unnecessary.

When RO Is Necessary

RO is essential when your water has:

1. High TDS (above 300 ppm)

RO is the only consumer technology that removes dissolved salts. If your TDS exceeds 300 ppm, UV and UF will not help — they only remove microorganisms and suspended particles.

2. Heavy metals

Lead, arsenic, mercury, and cadmium are dissolved in water and require RO. This is especially important in areas known for groundwater contamination — West Bengal (arsenic), Punjab (arsenic, uranium), Rajasthan (fluoride).

3. Chemical contamination

Pesticides, fertilizers, and industrial chemicals are dissolved contaminants that only RO can remove.

4. Borewell or groundwater source

Groundwater in most of India has high TDS and often contains heavy metals. If you use borewell water, you almost certainly need RO.

When RO Is Unnecessary

RO is overkill — and potentially counterproductive — when:

1. TDS is below 300 ppm

If your TDS is under 300 ppm, a UV or UF purifier is sufficient. RO would strip beneficial minerals and waste water for no benefit.

2. Municipal water supply (low TDS areas)

Cities like Mumbai (100–250 ppm), Kolkata (150–250 ppm), and Chennai (200–400 ppm for some areas) often have TDS below the RO threshold. A UV purifier with sediment filter is usually adequate.

3. Water is already treated (apartment complexes)

Many apartment complexes have central RO or softening systems. Check with your building management — if the building already treats water, you may only need a basic UV purifier for final microbial safety.

The TDS Decision Guide

TDS Level	Recommended Purifier	Reasoning
0–100 ppm	UF or UV	No dissolved solids to remove; UV for microbial safety
100–300 ppm	UV + UF	Microbial removal without stripping minerals
300–500 ppm	RO + UV	TDS reduction needed; UV for added microbial safety
500–1000 ppm	RO + UV	Definite RO requirement; high TDS needs membrane
1000+ ppm	RO + UV (commercial-grade)	Heavy-duty RO needed; may need pre-treatment

The Downsides of Unnecessary RO

Water wastage: Even modern RO units waste 1–2 litres for every litre purified. A family of 4 wastes 20–40 litres daily — 7,000–15,000 litres per year.

Mineral loss: RO removes calcium and magnesium, which are beneficial. Long-term consumption of RO water with very low TDS (below 30 ppm) may contribute to mineral deficiencies.

Cost: RO units cost ₹8,000–₹25,000, plus annual membrane replacement (₹2,000–₹5,000) and electricity for the booster pump.

Environmental impact: Discarded RO membranes and plastic filters add to plastic waste.

How to Decide

1. Test your TDS with a ₹500 TDS meter
2. Check your water source — municipal, borewell, or tanker
3. Get a lab test if TDS exceeds 300 ppm to identify specific contaminants
4. Match the technology to your actual needs, not to what the salesperson recommends

Key Takeaways

• RO is necessary only when TDS exceeds 300 ppm or heavy metals are present
• For low-TDS municipal water, UV or UF is sufficient and more economical
• Unnecessary RO wastes water (7,000–15,000 litres/year for a family of 4)
• RO removes beneficial minerals — look for a system with TDS controller or mineralizer
• Test your water before buying — don’t rely on assumptions or sales pitches