Understanding TDS UV & RO and What It Means

TDS (Total Dissolved Solids) is a measure of all minerals and salts dissolved in water — mainly calcium, magnesium, sodium, chloride, sulfate, etc.

• Below 300 ppm: Excellent, safe to drink.

• 300–500 ppm: Generally acceptable for adults but can be borderline for babies or people with kidney concerns.

• Above 500 ppm: Considered poor quality for long-term consumption (WHO guideline upper limit).

When rain and runoff raise your TDS to 500+, it’s likely bringing mud, organic matter, and dissolved salts from the source — so your UV system won’t remove those.

2. What UV Purifiers Actually Do

UV filters kill microorganisms (bacteria, viruses, cysts), but:

• They don’t remove dissolved solids, metals, salts, or hardness.

• They don’t change taste, odour, or turbidity (muddiness).

So while your UV system keeps the water biologically safe, it doesn’t address high TDS, sediment, or heavy metals.If your water is sometimes muddy or high-TDS, UV alone isn’t sufficient.

3. What RO (Reverse Osmosis) Does

RO pushes water through a semipermeable membrane that removes:

• Dissolved salts and minerals (reduces TDS)

• Heavy metals (lead, arsenic, fluoride)

• Nitrates and organic contaminants

But it also removes beneficial minerals like calcium and magnesium.That’s why modern RO systems often include a TDS controller or mineral cartridge to add back healthy minerals.

Pros:

• Great for TDS > 400–500 ppm

• Removes chemical and heavy metal impurities

• Consistent water quality year-round

Cons:

• Wastes about 2–3 L for every 1 L purified (newer models are better)

• Can reduce TDS too much (<50 ppm), making water slightly acidic and flat-tasting

• Needs regular maintenance (membrane and filters)

4. For Babies or Kidney Issues

For infants or people with kidney conditions:

• High TDS water (especially with sodium/calcium load) stresses the kidneys.

• Low-TDS RO water (<50 ppm) is safe but should ideally have re-mineralization for taste and pH balance.

• Avoid unfiltered groundwater or muddy tap water — risk of bacteria and heavy metals.

So in many cases, RO with remineralization or RO + UV + TDS control is the best compromise.

5. Practical Recommendation

Condition	Recommended System	Notes
TDS < 300 ppm, clear water	UV + sediment filter	Keep as is
TDS 300–500 ppm (varies, sometimes muddy)	RO + UV + TDS Controller	Ideal balance of safety and taste
Baby or kidney patient	RO with re-mineralizer	Maintains safe mineral level (~80–120 ppm)
Concern about wastage	Choose RO with “zero-waste” or tank-recirculation design	Some models recycle reject water

Summary

• Keep your UV unit if the source is stable and TDS < 300 ppm.

• Switch to RO + UV + TDS control if TDS regularly exceeds 400 ppm or water turns muddy.

• For your baby’s health, ensure moderate-TDS re-mineralized water (80–150 ppm) and boil it before formula use if unsure.

• Don’t worry about mild TDS variation — but avoid prolonged exposure to > 500 ppm water.