Reverse Osmosis Systems-BW series


The BW series skid mount reverse osmosis systems will treat feedwaters with up to 10,000ppm TDS and produce permeate water suitable for most applications. At the heart of the systems are low-energy, high performance reverse osmosis membranes capable of rejecting >99% of incoming TDS with recoveries up to 75%. Systems are skid mounted including the RO system and integrated pre-treatment systems (automatic backwash sediment filter, dechlorination filters and chemical dosing systems for anti-scalants as required). The skid is electro-polished stainless steel for corrosion resistance. Fitted controls include flow rotameters, pressure gauges, flow control valves and manual/auto electrical function selections. System operation is via a dedicated PLC or PLC/HMI.

Our industry standard high performance reverse osmosis membranes are optimised to give consistent performance, long in-service life and low maintenance. Particular design attention has been paid to energy efficiency through:

  • High performance low-energy, low fouling reverse osmosis membranes
  • High system recovery rates (up to 75%) to minimise waste water volumes
  • Optional VSD for RO pressure pump control
  • Optional HMI touch screen control panel for integration to external control systems
  • Optional feedwater boost pump
  • Choice of pre-treatment stages to suit feedwater quality

General specifications

These specifications are intended as a guide to the standard system configurations and performance under specified operating conditions. Alternate system configurations are available with specialised membranes, pressure vessels and corrosion resistant pumps for higher TDS feedwaters on request. All systems are supplied skid mounted with standard auto-backwash filter systems and RO components pre-plumbed. Control systems are all integrated with a single main PLC, conductivity monitor and electrical mimic panel.

Model BW9000 BW12000 BW15000 BW18000 BW21000 BW30000
Permeate flow (lpd/lph)

(according to feedwater)













Operating pressure 150-280psi (820-1850kPa)
Feedwater boost pump (optional) Grundfos/Stairs or equivalent s/s multi-stage type, 240VAC 1ψ or 415VAC 3ψ
Pre-filtration Cartridge filters in single or S/S cluster multi-element housings
Sediment filter (CLINO X) CNX1354 CNX1665 CNX1665 CNX1865 CNX2162 CNX2162
Control valve Automatic timer controlled type
Dechlorination (optional) ACF1354 ACF1665 ACF1665 ACF1865 ACF2162 ACF2162
Control valve Automatic timer controlled type
Dosing system Antiscalant dosing pump, chemical tank and level switch
High pressure pump Grundfos/Stairs or equivalent s/s multi-stage type, 240VAC 1ψ or 415VAC 3ψ
Membrane type High performance low energy type, FRP wrap
Membrane size/quantity

(Options for 8040 membrane size)

6 x 4040 8 x 4040

(2 x 8040)

10 x 4040

(3 x 8040)

12 x 4040

(4 x 8040)

6 x 8040 8 x 8040
Membrane pressure vessel High pressure FRP end port type
Vessel size and quantity

(Option for 8040 membrane size)

3 x 8040 4 x 8040

(2 x 8040)

10 x 4040

(3 x 8040)

4 x 12040

2 x 8080

3 x 8080 4 x 8080
Flow rotameters Permeate, concentrate and reject recirculation
Pressure gauges Feedwater, pump discharge and membrane discharge
Permeate quality monitor Permeate Conductivity (optional feedwater conductivity)
Electrical panel PLC control, contactors, relays, fuses, mimic panel (optional hours run meter)


Feedwater requirements with Antiscalant use (minimum quality)
Hardness <500ppm H2S 0.0ppm Free chlorine 0.0ppm
Manganese <5ppm TDS <1000/<5000<10000ppm TOC <10.0ppm
SDI <5 Temperature +5 to +40⁰C pH 3-10
Silica <10.0ppm Iron <5ppm Pressure >350kPa
RO system operating parameters
Minimum feed pressure 350kPa (50psi) Maximum pressure 1950kPa (285psi)
Minimum salt rejection 96% Maximum salt rejection 99.30%


Feedwater quality and type are key factors in the design of reverse osmosis systems and have a direct impact on choice of pre-treatment equipment, pumps and membrane choice. A feedwater water quality analysis is essential prior to final system selection and design. Options are available for most pre-treatment and control systems by request.

The Reverse Osmosis Process

Reverse osmosis is a very mature, well developed technology whose performance is easily measured. It is the method of choice for many industrial, municipal and commercial works when a reduction in feedwater TDS/conductivity or similar contaminants is required.

Osmosis is a term used to describe the diffusion of fluid through a semipermeable membrane from a solution with a low solute concentration to a solution with a higher concentration. Osmosis can be reversed if sufficient pressure is applied to the concentrated side of the membrane. This reversal process is used for water purification and desalination as the membrane allows only the water to pass through, but not larger molecules or ions (like salt).

For the reverse osmosis system to operate effectively, the feedwater must be filtered to remove suspended solids (to around 5 microns and then de-chlorinated. An anti-scalant injection system is generally required to remove hardness minerals (calcium, magnesium and iron) which would otherwise increase in concentration on the waste side of the membrane to the point where they form scale and foul the membranes. Water softeners may also be used to remove hardness minerals.

The pre-treated feedwater is pressurised and forced into a series of membrane and pressure vessel assemblies where the separation of pure water and contaminants occurs. Multiple membranes may be used for the higher flow rates and are housed in single or multi-place pressure vessels. RO membranes are available for a wide variety of feedwater types and all have a similar physical structure. They differ in membrane polymer type, membrane thickness, surface area, spacer thickness, outer membrane covering and physical size. Surface modified membranes are used in more specialised areas to yield maximum stable performance and are preferred with difficult feedwater types.


Pre-Treatment and Anti-scalant dosing system options

The following pages cover the pre-treatment modules, filtration and/or dechlorination media used, auto-backwash controller types and anti-scalant dosing systems used with the BW series systems. There may be installations where these pre-treatment stages need to be altered to deal with some poor feedwater types. With all our systems, the final system specification is made according to the feedwater analysis specific to the installation site.


ROtek BW Pre-treatment options

CNX Zeolite Sediment Removal Filter

System features:

  • Fully automatic operation
  • Choice of control valves, timer or volumetric types
  • Unfiltered water bypass or no-unfiltered water bypass.
  • Optional non-electric automatic controller
  • FRP media vessel pressure rated to 1050kPa
  • Longer filtration runs, less frequent backwashing
  • Filtration efficiency in >5µm size range
  • Service flow 610lpm/m² (15gpm/ft2) in pressure systems
  • Physical filtration, surface adsorption and chemical capture processes

Clino-X filters use a processed and graded mineral zeolite filtration media for sediment removal above a nominal 5µm. Clino-X tri-phase media has a high suspended-solids loading capacity (up to 1.5 times conventional multi-media and 2.8 times that of conventional sand filters) to extend periods between backwash cycles and reduce water consumption. Clino-X has an additional capacity for ion-exchange to remove a range of contaminants including ammonia, iron, manganese, copper, nitrate, arsenic, arsenic and free chlorine. Total ion-exchange capacity is 30,000ppm per kilo of media and the media may be regenerated with a brine solution.

Trapped particles are removed from the media bed by periodically reversing the water flow through the system. This periodic backwash is initiated by the control valve and frequency is selected by the user to suit the feedwater type and volume of water being used. Optional Magnum, Fleck or NE non-electric control valves are available for time, total volume, differential pressure or external contact closure triggers for backwash cycle initiation on request.

Model Volume Service Flow Rate Backwash Flow Rate *Standard


In/Out Thread Dimensions
CNX-1054 35.5 litres 24-41lpm 31-41lpm WS1-EI 20 mm 250 x 1400 mm
CNX-1354 63.5 litres 41-69lpm 52-69lpm WS1-EI 20-25 mm 330 x 1370 mm
CNX-1465 85 litres 48-80lpm 60-80lpm WS1-EI 25 mm 360 x 1650 mm
CNX-1665 99 litres 63-105lpm 78-105lpm 263/742 25-40mm 410 x 1650 mm
CNX-1865 150 litres 80 lpm 81 lpm 2850FT/NE 40mm 460 x 1650 mm
CNX-2162 170 litres 108-180lpm 135-180lpm 2850FT/NE 40 mm 530 x 1580 mm
CNX-2472 226.5 litres 141-236lpm 176-236lpm 2850FT/NE 40 mm 610 x 1850 mm
CNX-3672 523.5 litres 318-530lpm 396-530lpm 170/NE 50 mm 920 x 1830 mm
CNX-4272 764 litres 433-721lpm 539-721lpm 170/NE 80mm 1219 x 1830mm


Pressure drop through the filter will occur according to pipe diameters used on installation, typical flow rate and sediment loading on the media through use. An integrated three-valve bypass assembly is recommended for all installations to allow the system to be isolated should this be necessary. Inlet and outlet pressure gauges will also assist with system performance monitoring.

ROtek BW Sediment Filtration Media

Clino-X is a unique tri-phase media based on a rare naturally occurring mineral that has been extensively refined and graded. The unique properties of Clino-X allow it to radically alter the performance and operational costs of media filtration by combining physical filtration, surface adsorption and chemical capture processes. The hardness, stability and micro-porous character of Clino-X make it a perfect filtration media for applications in the water and wastewater treatment industry. Unique ion-exchange capabilities extend applications beyond sediment removal to provide additional capability to existing water treatment infrastructure

Filtration Performance

There is an increasing demand for media with higher efficiency in the removal of suspended solids and colloids from feedwaters. The ability of filtration media to remove other contaminants including heavy metals and other toxic substances, bacteria and parasites is also advantageous. Conventional sand filter systems do not remove such contaminants.

The filtration abilities of Clino-X offer a versatile and eco-sensitive option to remove such contaminants found in water systems. Clino-X media can perform these functions due to their high ion exchange capacity, adsorption-desorption energies and ability to modification.

Clino-X can remove ammonium (NH4+) and metal cations Pb+2, Cu+2, Cd+2, Zn+2, Co+2, Cr+2, Mn+2 and Fe+2/+3 from solutions with the recovery of ammonium and some metals as high as 97%


RO Pre-treatment, Cooling Towers

Municipal Water Treatment

Wastewater and Car Wash Recycling

Metal Finishing-

Irrigation, Horticulture and Hydroponics

Aquarium and Aquaculture

Bore Water Filtration


CLINO-X – Superior filtration media

Physical Characteristics

COLOR Dark Green
BULK DENSITY 55 lbs. per cu. ft.

Operational Requirements

SERVICE FLOW RATE 12 – 20 GPM/sq. ft.
BACKWASH FLOW RATE 12 – 16 GPM/sq. ft.
Allow bed to soak overnight before initial backwash.


CLINO-X vs. conventional filter media

NOMINAL                LOADING

MEDIA                                                                                         MICRON RATING                   CAPACITY

Sand 20 1.0 x
Sand and Anthracite 15 1.4 x
Multimedia 12 1.6 x
CLINO-X <5 2.8 x


Features and Benefits

  • High suspended solids loading capacity
  • Superior filtration performance
  • Reduced backwash frequency
  • Removal of solids to 5 microns
  • Reduced pressure drop
  • Higher flow rates
  • Ligh weight media, lower shipping costs
  • Easy to handle


CLINO-X Ion Exchange Performance Chart

Exchange Capacity: 30,000 mg/l for every 1KG of media
Contaminant Removal – tested at water hardness of 200 mg/l
Colour: 58%                         Turbidity: 95%                       Total Hardness: 62%      Fluorine: 32%
Zinc:   88%            Ammonia: 99%                   Iron: 99%                                                    Manganese: 92%
Copper: 70%     Phosphorus: 55% Cyanide: 62%               Nitrate: 14%
Haloforms: 55%    Chloride: 11%          Arsenic: 30%                   Lead: 98%
Mercury: 28%       Cadmium: 92%        Molybdenum: 70%         Nickel: 25%
Free Chlorine: 96%     Volatile Phenols: 85%

Contaminant removal efficiency may be affected if total hardness >200ppm

When CLINO-X has reached the limit of contaminant removal, it may be regenerated with a 30% sodium chloride solution in the same way that conventional water softeners are regenerated. CLINO-X is soaked in the saturated brine solution for 2 hours before rinsing and putting back into service. Regeneration is only required when the filter is designed for ion exchange purpose. If the filter is only used for turbidity removal, periodic backwashing will restore media performance.


ROtek BW Dechlorination Systems

ACF Activated Carbon Filter

  • Fully automatic, manual or in/out operation
  • Timer or volumetric controller and valve options
  • Industry standard FRP media vessel
  • Range of carbon types to suit different feedwaters
  • Pre-treatment interlock for RO interface
  • High maximum operating pressure (700kPa)
  • Extensive range of pressure vessel sizes
  • Optional dual tank systems

ROtek ACF automatic backwash carbon filters use high capacity acid washed, pH stabilised activated carbon media to remove chlorine, tastes and odours from feedwaters. By changing the type of carbon used and using the same hardware, we can also provide systems for removal of tannins, hydrogen sulphide and other odour producing contaminants from the feedwater stream.

In the AFC systems, feedwater flow is directed through the flow control valve and is distributed across the media bed via a specially designed diffuser. After passing through the media bed, treated water enters the internal strainer and riser tube located in the base of the tank and is returned to the flow control head before exiting. Suspended solids trapped in the media bed are removed by periodic reversal of the water flow initiated by the electronic control head on a time or volume basis.

Standard valves used allow untreated water to bypass the valve during backwashing to ensure a continuous supply of treated water downstream. A no-unfiltered-water-bypass (NUB) option is available to stop water flow exiting the treated water line during backwash. A manual backwash valve is optional if automation is not required. For feedwaters with low suspended solids loads, a simple IN/OUT head is also available

Model Media volume Service/Peak/Backwash flow rate range Feed water Turbidity Standard Control valve In/Out port Tank size

(dia. x h)

ACF-1054 35 F20: 6-10/21/21-25

WS1TC: 6-15/25/21-25

NTU<5 Timer

(Volumetric optional)

¾” or 1″ 10″x54″
ACF-1354 63 F20: 10-18/35/35-41

WS1TC: 10-22/38/45

NTU<10 Timer (UWB)

(Volumetric optional)

¾” or 1″ 13″x54″
ACF-1465 85 F20: 12-25/41/41-48

WS1TC: 14-30/45/41-48

NTU<10 Timer

(Volumetric optional)

1″ 14” x 65”
ACF-1665 99 15-27/53/53-63 NTU<10 Timer

(Volumetric optional)

1″ or 1.5″ 16” x 65”
ACF-2162 170 26-46/91/91-108 NTU<10 Timer

(Volumetric optional)

1.5” 21” x 62”
ACF-2472 225 35-60/119/119-141 NTU<10 Magnum 293-742 1.5” 24” x 72”
ACF-3072 368 54-93/187/187-221 NTU<10 Magnum 293-742 2″ 30” x 72”
ACF-3672 524 78-134/269/269-318 NTU<10 Magnum 293-742 2″ 36” x 72”
ACF-4272 764 106-183/366/366-433 NTU<10 Application specific 2″ or 3″ 42” x 72”
ACF-4872 1047 138-239/478/478-565 NTU<10 Application specific 2” or 3” 48” x 72”
  • Flow rate data shown is for removal of chlorine and related sanitisers. Flow rates will vary for different types of carbon and the application, data shown above is typical applications only and may vary due to feedwater quality and application.


  • Pressure drop through the filter will occur according to pipe diameters used on installation, flow rate and sediment loading on the media through use. An integrated three-valve bypass assembly is recommended for all installations to allow the system to be isolated should this be necessary at any time. Inlet and outlet pressure gauges will also assist with system performance monitoring. System flow rate will vary according to the application and type of contaminant removal required.

Rotek BW Dechlorination Media

ROtek GC1200N activated carbon is an acid washed, pH stabilised coconut husk based filtration media used to remove low molecular weight organic micro-pollutants, ozone and chlorine-based sanitisers from municipal feedwater sources.

ROtek GC1200N media is the most commonly used type of carbon used in pre-treatment stages prior to reverse osmosis treatment. The media has highly macro-porous granular structure to remove chlorine, low molecular weight organic contaminants and other commonly used sanitisers. GC1200N has a high hardness level to reduce the formation of fines and a high density to increase adsorption capacity. Acid washing removes fines and neutralises pH levels to simplify installation and handling. 

Typically, media is loaded in the appropriate quantity into the FRP media vessel and then soaked for 12-24 hours to completely wet the media surfaces. The dechlorination system is then backwashed until all fines and trapped air are removed and then it may be placed into service.


ROtek Auto-backwash Filter Controllers

Standard media pressure vessels used for filtration systems have 2.5”, 4” or 6” top openings for installation of flow control heads and pipework. Flow control valves may be manual or automatic, electrical or non-electric, and functions may be initiated through a simple timer, volume of water treated, or an external contact closure from a PLC, differential pressure monitor or contact closure. Choose the flow control valve and controller according to the application, required flow rates, mode of operation and FRP tank size. Some valve types are shown here and details on additional valves to suit specific applications are available by request.

FLOTROL F20 integrated flow control valve and controller

The F20 5 cycle valves are simple, easy to use 10-day timer actuated 1” filter control valves for 6” to 16” diameter FRP tanks with 2.5”-8 NPSM FRP openings. The valves are designed for smaller residential applications requiring flow rates up to 50lpm (1” option) at 103kPa pressure drop.   The valve uses a 1.05” riser tube and comes with an upper bayonet type screen. These are the valves of choice when simplicity and reliability are required for smaller flow rates and where untreated water bypass is acceptable during periods of no use.

NOTE:                The F20F valve has untreated water bypass during regeneration.

CLACK WS1CI integrated flow control valve and controller

xThe WS1CI 6-cycle valves are simple, easy to use timer actuated 1” softener control valves for 6” to 21” diameter FRP tanks with 2.5”-8 NPSM FRP openings. These versatile valves are primarily designed for commercial applications requiring flow rates up to 102lpm at 103kPa pressure drop.   The valve uses a 1.05” riser tube and comes with an upper bayonet type screen. Standard supply includes a bypass assembly as standard to simplify service requirements.

NOTE:                The WS1CI valve has untreated water bypass during regeneration

263 Performa Valve – 400 Series

The 263 Performa model is an automatic 3-cycle 1” Filter valve designed for larger residential and light commercial applications with higher service flow rates to 95 LPM at 103kpa drop and backwash flow rate of 76 LPM at 170kpa drop. The Performa valves are supplied complete with a 400 or 900 Series Control with transformer and have four external ports that allow the valves to be configured to suit most applications.

NOTE:                The 263 valve has untreated water bypass during regeneration.

AUTOTROL 150 Series – Logix 700 Series flow control valve and controller

The 150/153-316 Stainless Steel valve is a 1.5”, 3-cycle filter valve designed for commercial and industrial applications with flow rates to 216lpm @ 103kPa pressure drop. The valve is 316 grade stainless steel, piston operated and is available in top or side mount configurations.

NOTE:                The 255 valve has untreated water bypass during regeneration

AUTOTROL MAGNUM Cv Series – Logix 700 Series flow control valve and controller

The Magnum Cv is a 1.5” or 2” flow control valve is moulded from Noryl available with an external flow metering turbine. Used for commercial and industrial applications, the valve provides for flow rates up to 285lpm @ 103kPa pressure drop. All options including backwash flow control are ordered separately.

OPTIONS: 2” PVC solvent weld or 2” BSP Stainless Steel adaptor kit

NOTE:                The Magnum valves can be supplied with or without untreated water bypass

Valve Controller Types

Logix 742 Time Clock controller for 255 series flow control valves

This simple time clock control provides the option of a selected day of week regeneration or can be programmed from ½ a day up to 99-days regeneration frequency setting. The 742 has an adjustable backwash between 0 to 200 minutes and purge between 0 to 200 minutes. This control includes a remote regeneration input signal as a standard option allowing for a dry contact signal.

Logix 762 Time Clock controller for 255 series flow control valves

This simple, economy electronic demand (volumetric) control initiates a regeneration cycle based on the volume of water treated. Programming is simple and incorporating a 28-day variable reserve feature with the ability to regenerate immediately once a volume of water is treated. The 762 has an adjustable backwash between 0 to 200 minutes and purge between 0 to 200 minutes. Features include a calendar override that can be set to regenerate between ½ and 99 days.

ROtek Anti-Scalant Dosing Systems


The OL.BP Olimpia solenoid driven dosing pumps are compact, lightweight and weatherproof to simplify installation for most applications.

Pump features include:

  • IP65 rated polypropylene casing which is fireproof and acid resistant
  • 0-100% manual adjustment of pump speed
  • Manual air bleed valve for priming
  • Operational status LED indicator
  • Quick connect tubing fittings
  • Low operating noise


Typical installation schematic

Two models are available in this range.

  • The OL BP 5-5 delivers up to 5 litres/hour at up to 5 Bar pressure
  • The OL BP 2-7 delivers up to 2 litres/hour at up to 5 Bar. (See performance curves above which illustrate flow rate vs. pressure for both models)
  • Both pumps have a fixed stroke (0.46/0.33cc/stroke) with a variable speed drive (0-100%) with a maximum 180 strokes/minute.
  • Probe input for connection of chemical storage tank level sensor.
  • Electrical power consumption is 15W
  • Pump weight is 1.5kg.


Rotek Anti-Scalant Chemical Storage Tanks

The ST series polyethylene storage tanks are used as part of a complete dosing system and provide a stable base for mounting the dosing pump and chemical level sensor in a single, compact unit. Tanks are fitted with a drain valve to simplify periodic cleaning and chemical formulation changes. The large recessed screw cap allows easy access for addition of fresh chemical and diluents.


ST-60l tank with dosing pump and level sensor

400x610mm (dia x h)

ST-100l tank with dosing pump and level sensor

500x600mm (dia x h)

ST-200l tank with dosing pump and level sensor

550x900mm (dia x h)

Screw lid types

200 & 120mm dia.



  • Compact design to minimise footprint requirements.
  • Manufactured using high quality UV-stabilised polyethylene.
  • All wetted surfaces are food grade polyethylene.
  • Available in 60, 100 and 200 litre capacities
  • Graduations moulded into tank body and tank drain port connection
  • Large, easy access screw cap
  • Tank top ideally suited for direct mounting of chemical dosing pumps
  • Easy to install or move with recessed handles

All wetted surfaces are UV stabilised, dye free, heavy metal free polyethylene and are ideal for the storage of most chemical solutions and purified waters exiting smaller reverse osmosis or deionisation systems.

Production takes place under strict quality control procedures on the latest state-of-the-art moulding equipment programmed to ensure consistent wall thickness and to provide adequate strength where it is needed most.

Our tank range is extensive with models for indoor and external installation. Rotationally moulded tank sizes run from to 60 to 22,500 litres in round, squat, slimline, low profile and brick shapes. Thermal welded PVC tanks are available in sizes from 50 to 200 litres for specific applications.