RO vs UV vs Gravity: Which Water Purifier?
This is one buying decision that genuinely depends on a fact about your water, not preference.
If your water source has high TDS — common with borewell or hard water — RO is generally the right choice. If your water is already low-TDS, like treated municipal supply, but you're concerned about bacteria or viruses, UV alone can be enough. If you're unsure of your TDS, an RO+UV combination covers both cases.
This decision is different from most appliance choices, because it depends on a specific fact about your water, not just preference or budget. Buying RO for already-low-TDS water wastes water in the purification process for no real benefit. Buying UV-only for high-TDS water won't remove the dissolved salts at all.
Our category page covers what we stock. This guide covers how to actually decide, based on your water.
Why TDS is the deciding factor
TDS — total dissolved solids — refers to the minerals and salts dissolved in your water. A simple TDS check, which many purifier brands and local water testing services can provide, tells you which purification technology genuinely applies to your situation, rather than guessing.
Borewell water and generally 'hard' water tend to have higher TDS. Treated municipal supply is often lower-TDS, though this can vary by area and season.
RO vs UV vs gravity — what each actually removes
RO (Reverse Osmosis)
- Removes dissolved salts and minerals, effective on high-TDS water like most borewell or hard water sources
- Needs electricity to run the pump
- Produces some wastewater as part of the filtration process
- Often reduces TDS further than ideal, so many RO systems add minerals back afterward
UV (Ultraviolet)
- Kills bacteria and viruses using UV light
- Does not remove dissolved salts or reduce TDS at all
- No wastewater produced
- Only appropriate where the water source already has acceptably low TDS
Gravity-based
- No electricity needed, works anywhere
- Filters sediment and some contaminants, but doesn't remove dissolved salts or reliably kill all biological contaminants the way UV does
- Lowest ongoing cost
- Best suited to already-safe, low-TDS water needing just extra filtration
When to combine RO and UV
Many municipal water supplies vary seasonally or have inconsistent treatment. An RO+UV combination purifier handles both dissolved solids and biological safety without needing to know your exact TDS year-round — a reasonable default if you're unsure.
Key decision factors
Your water source's TDS level
The single biggest factor — get your water's TDS checked if you don't already know it.
Power supply reliability
RO and UV both need electricity to run; if your area has frequent outages, factor in storage capacity or consider gravity for backup.
Storage capacity
Areas with irregular water supply benefit from a purifier that stores more purified water for use between fills.
Filter and membrane maintenance
RO membranes and filters need periodic replacement — factor this ongoing cost in, not just the purchase price.
Common mistakes to avoid
Buying RO without knowing your TDS
If your water is already low-TDS, RO wastes water in filtration for no real purification benefit over UV.
Buying UV-only for high-TDS water
UV kills biological contaminants but does nothing for dissolved salts — it won't fix hard or high-TDS water.
Ignoring ongoing filter costs
The purifier's purchase price is only part of the cost — factor in how often filters and membranes need replacing.
Frequently asked questions
Ready to choose?
See the RO, UV and gravity purifiers we carry.
Still not sure?
Message us on WhatsApp with your specific situation and we'll help you think it through.