The Shuddho water guide
RO, UV and UF solve different water problems. Start with where your water comes from, ask for a recent TDS reading, then balance capacity and maintenance for your household.
Technology, plainly explained
No single stage answers every situation. A combined purifier should have a clear reason for each stage rather than using stage count as shorthand for quality.
The comparison table can be scrolled horizontally on smaller screens.
| Stage | Main job | Useful when | Important trade-off |
|---|---|---|---|
| RO Reverse osmosis | Uses a membrane to reduce many dissolved solids and salts. | TDS is consistently elevated, taste is noticeably saline, or a qualified assessment indicates dissolved-solids reduction is needed. | Needs pressure, electricity on most models, membrane care and a reject-water outlet. It can be unnecessary for already-low-TDS water. |
| UV Ultraviolet | Exposes flowing water to UV light to inactivate susceptible microorganisms. | The source is relatively clear and low in dissolved solids but microbial reliability is a concern. | Does not remove dissolved salts or visible sediment. Lamp output, sleeve cleanliness, flow rate and electricity matter. |
| UF Ultrafiltration | A fine membrane reduces suspended particles and many larger microorganisms. | Water has low TDS, pressure is modest, or a non-electric barrier is preferred. | Does not reduce dissolved salts. Membrane flushing is needed, especially with turbid water. |
| SED Sediment | Catches sand, rust, pipe flakes and other visible particles. | Water arrives cloudy after line work, from an overhead tank, or carries grit. | It is a protective pre-filter, not a complete purifier. Dirty source water can shorten cartridge life. |
| AC Activated carbon | Adsorbs many taste- and odour-causing compounds, including residual chlorine. | Municipal water smells chlorinated or organic taste and odour need improvement. | Capacity is finite and varies by water quality. Timely replacement prevents exhausted media from becoming ineffective. |
| MIN Mineral / taste stage | Adjusts taste after RO; formulations vary by cartridge. | An RO system produces flat-tasting water and the cartridge composition is clearly documented. | It does not replace source-appropriate purification, and “mineral” is not a measurable quality promise by itself. |
| COMBO Combined system | Sequences pre-filtration, a primary treatment and a final polishing stage. | Mixed or seasonally changing supplies need more than one treatment approach. | More components mean more consumables and service points. Ask what each stage is intended to address. |
Useful distinction: TDS is not a cleanliness score. A low reading can still coexist with microbial or storage-tank concerns, while a higher reading does not identify which dissolved substances are present.
Common Bangladesh scenarios
Neighbouring buildings can receive similar supply water and still have different results because of pumps, underground reservoirs, rooftop tanks and internal pipework.
Source 01
In Dhaka, Chattogram and other city systems, water may pass through a building reservoir and rooftop tank before reaching the tap. Tank hygiene and ageing pipes can matter as much as the incoming line.
Source 02
Groundwater characteristics vary significantly by locality. Iron staining, hardness, salinity or elevated dissolved solids may affect taste, fixtures and purifier choice.
Source 03
Backup water can change from delivery to delivery. A building that switches between municipal, groundwater and tanker sources may see shifting TDS, sediment and taste.
From uncertainty to a shortlist
Write down the answers. They help a seller recommend fewer, more relevant options and make future service costs easier to estimate.
Ask Shuddho to review your scenarioNote municipal, groundwater, tanker or jar water, plus underground and rooftop storage. If the source changes seasonally, choose for the least predictable regular source rather than today’s sample.
Take several TDS readings on different days, record taste, odour, visible particles, scale and staining, and seek source-appropriate lab testing where local conditions warrant it. Do not select RO from one reading alone.
A household of 2–4 may be comfortable with roughly 7–8 litres of storage, while larger families or small offices may need 10–12 litres and faster recovery. Consider cooking water, guests and load-shedding periods.
Confirm cartridge prices, availability, expected replacement triggers, membrane/lamp costs, service coverage and reject-water routing. The best system is one you can maintain on time.
Cost of ownership
A lower-priced unit can cost more over three years if cartridges are uncommon, source water exhausts filters quickly, or every visit carries a separate charge. Request a written, model-specific estimate.
Sediment and carbon filters are recurring items. UF and RO membranes, UV lamps, pumps and storage-tank components typically have different replacement cycles. Replace by condition, measured performance and maker guidance, not a universal calendar claim.
UV and most domestic RO units use electricity. RO also produces a reject stream; the volume depends on pressure, membrane and design. Ask the installer to measure operation and route reject water safely for suitable non-drinking uses where practical.
Include diagnostic visit charges, labour outside a plan, difficult wall or plumbing access, and source-specific pre-filters. Iron-heavy or very turbid water may need treatment before the purifier, adding both equipment and maintenance.
An illustrative planning range
Set aside roughly ৳2,500–৳8,000+ per year for routine filters and service on a household unit, with RO membranes, UV lamps, pumps, unusual source conditions and parts potentially adding more.
Indicative only, not a quote. Actual intervals and costs depend on model, usage, incoming water and service coverage. Confirm current prices before purchase.Ready for the next step?
Compare suitable purifiers or request a service conversation if your source changes, TDS varies, or you need help reading the signs.