Membranes
Pentair Merlin Tankless RO System
Pentair Merlin tankless RO for point-of-use. Match water tests, pressure, flow, drain, sanitation, consumables, commissioning, and laboratory verification.
Pentair Merlin RO is a tankless point-of-use reverse-osmosis system with two membrane elements and a reject-water drain. PT Watermart Perkasa helps match a unit or replacement components using the water test, feed pressure, target flow, under-counter space, drain, and installation condition; model and availability are confirmed at quotation.
Updated 30 July 2026: the Merlin page was separated from control-valve content, rating data was tied to its test basis, and current Watermart POU choices were clarified.
Is Pentair Merlin RO suitable for your requirement?
Pentair Merlin or the PRF-RO architecture is worth reviewing when a buyer needs higher point-of-use flow without a pressurized storage tank. The Pentair PRF-RO installation manual, published in 2019, shows two TFC-350 IND elements, prefiltration, postfiltration, a cold-water feed, and a reject-water line. It specifies 40-80 psi (2.8-5.5 bar) feed pressure and 40-100°F (4-38°C) feed temperature.
Merlin, PRF-RO, old part numbers, and historical configurations should not be treated as one identical active product. Send the complete nameplate and every cartridge label so Watermart can determine whether the request concerns a complete system, membranes, prefilter, postfilter, manifold, or installation accessories.
| Buyer requirement | Information to provide | Procurement decision |
|---|---|---|
| New unit | Water test, peak flow, dynamic pressure, space, power if applicable, drain, and outlet count | Whether tankless RO or another POU system is the better fit |
| Existing-unit replacement | Nameplate, serial/model, all cartridge labels, connections, and replacement reason | Complete unit, retrofit, or migration to an available model |
| Membrane or consumables | Old part number, quantity, replacement date, product flow, feed/product TDS, and sanitation history | Part compatibility plus flushing and commissioning scope |
| Light-commercial use | Hourly demand profile, peak draw, service space, drain, operator, and maintenance schedule | One unit, multiple POU units, or a central commercial RO system |
What does the 748 gpd Merlin I rating mean?
The 748 gpd (2,831 L/day) figure is a Merlin I system rating under the manufacturer’s stated test conditions, not a guaranteed flow at every installation. A legacy Merlin I performance data sheet lists 748 gpd product-water production and 23.7% average recovery and efficiency without a pressurized storage tank. That document also lists system part 1205052, prefilter 1237460, membrane 1238342, and postfilter 1244746.
| Site factor | Why actual output can differ |
|---|---|
| Dynamic pressure | Pressure can fall when other outlets open, reducing membrane driving pressure |
| Temperature | Colder feedwater generally reduces permeate flow |
| TDS and water chemistry | Osmotic pressure, hardness, iron, manganese, silica, and organics affect performance and fouling |
| Pretreatment | Sediment, chlorine, hardness, and foulants must be controlled within element limits |
| Consumable condition | A blocked prefilter, fouled membrane, or old postfilter restricts flow and quality |
| Tubing and drain | Long tubing, fittings, back pressure, or an incorrect reject line reduces performance |
Use the rating only for initial screening. Request documents and certification status current for the exact code and destination market at procurement; a legacy performance sheet is not evidence of current availability or certification.
Pentair Merlin, ES60-S, or a non-RO POU filter?
The best choice follows the water test and outlet requirement rather than the technology name. For a new project, Watermart can compare a legacy Merlin/PRF-RO installation with the currently offered Pentair ES60-S under-sink RO system or Pentair EU-25 and Everpure point-of-use filters when RO-level TDS reduction is unnecessary.
| Choice | When to consider it | What to calculate |
|---|---|---|
| Merlin/PRF-RO tankless | An installed unit needs assessment, or tankless POU flow is required | Model/part status, pressure, peak flow, reject water, drain, and consumables |
| Pentair ES60-S | A currently offered Watermart under-sink RO system is required | Water test, capacity, recovery, sanitation, consumables, space, and drain |
| Pentair EU-25 or Everpure | Feed TDS is already suitable and the target is sediment, taste, odour, or a defined POU barrier | Cartridge claims, flow, pressure, sanitation, replacement interval, and result testing |
| Central commercial RO | Many outlets have high demand and one team owns operation | Peak flow, storage, redundancy, reject water, cleaning, sampling, and total cost of ownership |
For building water, pretreatment such as the Pentair C500 automatic prefilter can be assessed ahead of POU treatment, but the final train must still follow the water test and pressure profile.
How should installation and treated-water quality be verified?
Merlin or PRF-RO does not make water ready to drink merely because the equipment is installed. Pentair’s manual prohibits use on microbiologically unsafe water or water of unknown quality without adequate disinfection, requires a cold-water feed, and calls for flushing after new membrane installation.
- Test the feedwater and set targets from the applicable Indonesian drinking-water requirements.
- Measure static and dynamic pressure, temperature, TDS, hardness, iron, manganese, chlorine, and other risk parameters.
- Verify the cold-water feed, a properly air-gapped drain under local rules, service space, tubing, and the absence of a pressurized storage tank where the architecture prohibits one.
- Install matched consumables, flush and sanitize, perform leak checks, and record feed and product TDS.
- Keep cartridge-change, sanitation, pressure, flow, reject-flow, and sampling logs.
- Use representative sampling and laboratory verification before stating that treated water meets drinking-water requirements.
Send these inputs through the PT Watermart Perkasa contact form so the quotation separates equipment, consumables, installation, commissioning, and testing.
Pentair Merlin RO buyer questions
Is Pentair Merlin still available as a new system?
The old name and part numbers need confirmation at quotation. PT Watermart Perkasa does not promise availability from this page; send the nameplate and part number so the team can confirm the unit, consumables, alternatives, lead time, and support boundary in writing.
Can Merlin RO use a pressurized storage tank?
Pentair’s PRF-RO manual says the system is designed without a pressurized storage tank and that adding one negatively affects performance. If a project needs buffer storage, the tank, level control, sanitation, and distribution should be reviewed as a separate system.
Is water from Merlin RO automatically ready to drink?
No. Drinking-water suitability requires applicable Indonesian standards, suitable feedwater, pretreatment, commissioning, sanitation, consumables logs, representative sampling, and laboratory verification of the treated water.