What is RO reverse osmosis? RO (reverse osmosis) filters through a semi-permeable membrane, reducing dissolved impurities, heavy metals, mineral salts and most dissolved matter for cleaner-tasting drinking water.
What is UF ultrafiltration? UF (ultrafiltration) filters through hollow-fibre membranes, reducing larger particles, impurities and some micro-organisms while keeping minerals, and mostly runs without electricity.
| Reverse Osmosis (RO) | UF Ultrafiltration | |
|---|---|---|
| Mainly addresses | Dissolved impurities, heavy metals, mineral salts, most dissolved matter | Larger particles, impurities, some micro-organisms |
| Heavy metals (dissolved) | Reduced | Not reduced (metal ions pass through) |
| Minerals | Substantially reduced | Retained |
| Salty taste / high TDS | Reduces TDS and dissolved salts | Does not reduce dissolved salts |
| Electricity | Usually needs an electric pump | Mostly runs without electricity |
| Waste water | Produces a small amount of concentrate in operation | Generally produces no waste water |
| Suitable for | For the cleanest taste, or salty / high-TDS water | To keep minerals, for high usage, or to save electricity |
Note: filtration reduces impurities and improves taste — it does not remove everything; actual results depend on the incoming water and the system's condition.
In Hong Kong and Macau, drinking water quality is a common concern for residents and businesses alike. Macau's water conditions vary with building age and supply system upkeep, and some districts set a higher bar for drinking water filtration. Reverse osmosis (RO) and ultrafiltration (UF) are the two common treatment technologies, each with its own principles, applications and maintenance profile. This article unpacks how both systems work, looks at residential and commercial use, and compares maintenance and cost, to help you choose the right Water Purifier and Water Dispensersolution.
How it works
Reverse osmosis (RO): an RO system uses a semi-permeable membrane to remove nearly all dissolved solids (TDS) from water, including salts, heavy metals and organics. With a pore size of roughly 0.0001 micron it filters out the smallest molecules, so RO water comes close to purified water in effect.
Ultrafiltration (UF): a UF system filters through membranes with pores of roughly 0.01 micron, mainly removing suspended solids, bacteria and some viruses, though not dissolved solids.
For homes and for business
Reverse osmosis systems
For residents of Hong Kong and Macau, RO suits households and commercial premises that need higher-precision filtration. In Hong Kong, the Water Supplies Department treats and disinfects mains water rigorously, but some older buildings (especially public housing, tong lau and single-block buildings of thirty years or more) still have upkeep problems in their internal supply systems — ageing, leaking pipework and under-cleaned tanks among them — which can affect water at the tap. In Macau, older buildings face similar internal pipe ageing. An RO system helps reduce dissolved solids and some impurities, a useful supplement to everyday water-quality management.
For office use, an RO system likewise provides higher-precision drinking water for daily staff needs. RO-filtered water is also lower in dissolved solids, which helps reduce limescale in kettles.
Further Reading:commercial water dispenser buying guide
Ultrafiltration system
UF suits central filtration — treating the tap water for a whole building or every outlet in a home, covering kitchen, bathroom and basins. Whole-home UF helps improve the perceived quality of everyday water, especially for users worried about old pipes or tank upkeep.
In offices, UF also delivers filtered drinking water at speed, for daily drinking and pantry equipment.
Further Reading:6 Benefits of Central Water Filtration: An Installation Guide for Hong Kong Village Houses
Maintenance and cost
RO systems: RO delivers high-purity water, but maintenance costs are comparatively high, with the membrane and other parts needing regular replacement. The process also produces reject water, so installation needs a drain or outlet arranged.
UF systems: maintenance is simpler and cheaper. Many newer UF membranes last a long time and supply water on demand, well suited to daily use in Hong Kong and Macau homes and offices.
Which to choose
If filtration precision matters most: an RO system effectively removes dissolved solids and some impurities, suiting homes and commercial premises with higher drinking-water expectations — particularly common in older buildings in Macau and Hong Kong.
If you want simple installation and instant supply: a UF system is relatively easy to install and cheap to maintain, good for daily drinking and cooking, and works well as central filtration to improve the perceived water quality of a whole home or office.
In short, choosing between RO and UF in Hong Kong and Macau comes down to the building's condition, installation space, usage and maintenance arrangements. Each has its place; before deciding, understand the actual water conditions and installation constraints, then match the equipment to them.
Frequently asked questions
What is the biggest difference between RO and UF systems?
The main differences are filtration precision and mechanism. An RO membrane's pores are around 0.0001 micron, trapping dissolved solids, some metal ions and many organics, so filtered water has a lower TDS (total dissolved solids). A UF membrane's pores are around 0.01 micron, mainly removing bacteria, colloids and suspended matter, but not dissolved minerals. RO produces a small amount of reject water (concentrate); UF generally produces none. They suit different situations — understand your actual filtration needs before choosing.
For a Hong Kong or Macau home or office, RO or UF?
It depends on usage, water-quality goals and the installation environment. For households or venues that need TDS or particular dissolved matter addressed, RO is usually the better fit; if the main need is removing bacteria and colloids while keeping minerals, UF is the simpler option. Offices and commercial sites can compare by daily volume, space and maintenance arrangements. If in doubt, have the supplier assess on site and decide by the actual installation conditions.
RO produces reject water — how much does that affect daily use?
The reject water (concentrate) an RO system produces varies by design; typical home systems run at roughly 1:1 to 3:1 reject-to-pure, with newer models improving on that. It usually goes to the drain, so confirm the kitchen or installation spot has suitable drainage first. For a typical household the volume has limited impact on overall usage, but plan for where it goes to keep the installation feasible.
How different are the long-term maintenance costs of RO and UF?
UF cartridge replacement usually costs less and comes round less often, and some models can be flushed regularly to extend their life. RO needs its pre-filters, membrane and post-filter replaced on schedule, so overall upkeep costs more, though cycles depend on usage and water quality (the membrane typically every 1 to 2 years). When totting up long-term cost, include equipment, consumables, servicing labour and reject-water drainage. Ask the supplier for a clear maintenance quotation before buying so comparisons are fair.
Want to see suitable Office Water Dispenser options for offices and commercial premises? Compare Bio-Link's current commercial solutions by headcount, space and maintenance needs:
- ST1523: suited to medium and large offices, with higher capacity and RO filtration for shared pantries.
- ST9102: suited to schools, educational institutions and heavily shared venues — durable design with steady maintenance arrangements.
- STC15: suited to small offices, clinics or studios with limited space, supporting compact commercial installations.
Interested in a home-friendly Water Purifier or Water Dispenser options for the home? Compare Bio-Link's current home solutions by installation space and daily needs:
- RO838: an under-sink RO filter with multi-stage filtration, suited to kitchen installation for daily drinking and cooking.
- DT400: tabletop instant-hot water dispenser; filtration options can be added depending on installation conditions. Suitable for kitchens or living rooms.
Why choose Bio-Link?
Bio-Link (霸力純水濾水系統) is one of Hong Kong and Macau's longest-established reverse-osmosis (RO) drinking-water specialists, operating since 1997 — nearly three decades focused almost entirely on RO. We supply, install and maintain direct-piped RO and UF drinking-water systems for homes, offices, schools, clinics, restaurants and hotels across Hong Kong and Macau, with one company handling supply, installation and maintenance end to end, to buy or to rent, with clear costs. Our full filtration line is SGS-tested and designated models meet NSF 42 & 58; Bio-Link is a certified Social Enterprise (HKCSS / SEE Mark SEE0195).
Further Reading:Reverse osmosis - Wikipedia
Related Further Reading
This article focuses on comparing RO reverse osmosis with UF ultrafiltration. For the basics of RO water — the concept, how it works and where it is used — start with the main guide What Is RO Water? The Complete Guide to Reverse Osmosis Filtration in Hong Kong and Macau.
RO and UF systems apply across different commercial settings. For scenario-based solutions, see School Water Dispenser,Restaurant Water Filtration Systems or Hotel Water Filtration System.