Two suppliers quote a 20 m³/h industrial reverse osmosis system. Both offer branded membranes, stainless steel pumps and PLC control—but their prices differ significantly.

The difference may reflect equipment quality, design assumptions, included services or performance commitments. A lower price may also exclude equipment needed to meet your actual operating requirements.

The first step is to compare technical requirements and supply scope. Price comparison comes after those differences are clear.

Use the following 12 checks to identify gaps and evaluate industrial RO quotations on a consistent basis.

 

1. Confirm a Common Design Basis

Send every supplier the same request for quotation, including:

• • Raw-water analysis and source.

• • Seasonal feedwater temperature and water-quality variations.

• • Required hourly and daily water supply.

• • Target product-water quality.

• • Operating hours and site utility conditions.

TDS alone is not enough to define the treatment requirements. Hardness, alkalinity, silica, iron, manganese and other relevant constituents can change the pretreatment and membrane design.

Ask suppliers to identify assumptions and deviations explicitly. Missing information should remain “not confirmed” until clarified.

For projects with seasonal salinity changes, How Variable Feedwater TDS Affects RO Pump and Membrane Selection explains why average water conditions may not provide an adequate design basis.

 

2. Distinguish Rated Capacity from Guaranteed Water Delivery

Confirm whether the quoted capacity refers to feedwater flow, RO permeate flow or final usable water after downstream treatment.

Then check the guarantee conditions, measurement point and daily operating schedule.

For example, a system producing 20 m³/h for 22 compliant production hours generates 440 m³/day before any subsequent internal water consumption. It does not automatically deliver 480 m³/day.

Where daily supply is critical, request both:

• • Guaranteed operating flow under agreed conditions.

• • Net daily delivery after defined interruptions and internal consumption.

Avoid counting the same loss twice. Startup diversion already excluded from compliant production time should not be deducted again.

These distinctions are explained in Rated Capacity vs Guaranteed Net Permeate: What RO Buyers Should Confirm.

 

3. Specify Product-Water Quality and Delivery Conditions

A salt-rejection percentage does not replace a final water-quality specification.

Each quotation should define the maximum conductivity or TDS, the reporting basis and any application-specific limits. It should also identify where quality is guaranteed and what delivery pressure is available.

Descriptions such as “high-purity water” need measurable criteria. Conductivity alone does not establish compliance with microbiological, organic or other application-specific requirements.

If a second RO pass, EDI, UV or another treatment step is necessary, confirm whether it is included. A guarantee at the RO skid outlet may differ from a guarantee at the factory’s final delivery connection.

 

4. Check Recovery and the Complete Water Balance

Recovery determines how much feedwater is needed and how much concentrate is produced.

For a simple single-pass system without recycle:

Feedwater flow = Permeate flow ÷ Recovery

A system producing 20 m³/h at 75% recovery requires approximately 26.7 m³/h of feedwater and produces 6.7 m³/h of concentrate.

This calculation excludes pretreatment backwashing and other utility-water demands.

Higher recovery is not automatically a better offer. Ask for the supporting scaling assessment, chemical-dosing assumptions and membrane operating limits.

If the design includes recycle or multiple passes, request a water balance that distinguishes fresh feedwater, internal circulation, final product water and discharged concentrate.

 

5. Review Pretreatment Duties and RO Inlet Requirements

Compare pretreatment by its intended function and design capacity, rather than the number of vessels listed.

Depending on the water source, review:

• • Media filtration and backwash requirements.

• • Activated carbon or chemical dechlorination.

• • Softening or antiscalant dosing.

• • Iron and manganese removal.

• • Cartridge-filter specifications and replacement access.

Pretreatment should be sized for the required feedwater flow, not simply the nominal RO product-water capacity.

If another contractor supplies pretreatment, define the required RO inlet conditions, verification methods and responsible party. Otherwise, the RO guarantee may depend on water quality that nobody has clearly committed to provide.

 

6. Verify Membrane Models and Array Design

A membrane brand name is only the starting point.

Request the exact model, quantity, active membrane area and pressure-vessel arrangement. Clarify the number of stages and passes: staging within an RO train is different from treating first-pass permeate in a second pass.

Ask for a design projection showing performance under the agreed conditions and the assumptions used for membrane aging or fouling.

More membranes or lower average flux do not independently prove a better design. Flow distribution, element operating limits and feedwater characteristics must also be considered.

Where suppliers propose different element sizes, 4040 vs 8040 RO Membranes: Which Size Is Right for Your System? provides additional context.

 

7. Compare Pump Duty and Energy Consumption

Evaluate the high-pressure pump at the required flow and pressure, rather than comparing motor power alone.

Confirm the pump model, performance curve, efficiency, wetted materials, seal specification and available suction conditions. Electrical requirements should match the site voltage, frequency and supply arrangement.

If a VFD is included, identify the controlled variable and operating limits.

For energy comparison, use the same design conditions and equipment boundary:

Specific energy consumption = Electrical energy consumed ÷ Usable water produced

A figure covering only the high-pressure pump cannot be directly compared with one covering pretreatment, RO, EDI and distribution.

Also distinguish installed motor capacity from expected electrical power consumption during operation.

 

8. Identify Materials and Pressure Ratings by Component

“Stainless steel system” is too broad to support a meaningful comparison.

Ask suppliers to identify materials separately for the frame, pump wetted parts, high-pressure piping, low-pressure piping, valves, fittings and instrument connections.

Confirm that pressure-containing components have suitable pressure and temperature ratings. Seals and other wetted materials must also be compatible with the process water and intended cleaning chemicals.

Material selection should follow actual service conditions. Where certificates, material traceability or fabrication records are required, include them in the RFQ rather than requesting them after manufacturing.

 

9. Compare Automation by Function

“PLC automatic control” does not establish the extent of monitoring or equipment protection.

Review the instrument list together with the control description. Confirm which measurements are displayed locally, which reach the PLC and which trigger automatic actions.

Key functions to clarify include:

• • Low-feed-pressure and high-pressure protection.

• • Flow and recovery monitoring.

• • High-conductivity product-water handling.

• • Tank-level and critical dosing interlocks.

• • Sensor-failure responses.

• • Data logging and optional remote monitoring.

A touchscreen can display a process without providing every necessary protective function. What Online Instruments Are Essential for an Automatic RO System? explains how measurement points and control responses should work together.

 

10. Confirm Available Capacity During Maintenance

Check whether the quoted capacity requires every RO train to operate simultaneously.

Two 10 m³/h trains provide 20 m³/h together. When one is unavailable, the remaining train normally supplies 10 m³/h, provided shared equipment remains operational.

Shared feed pumps, pretreatment, dosing systems or electrical supplies can affect both trains. Ask suppliers to identify these dependencies and state the available output during planned maintenance.

Also review physical access for membrane removal, filter replacement and pump servicing.

For continuous-production facilities, One 20 m³/h RO Train or Two 10 m³/h Trains: Which Design Is Better? helps distinguish partial operating flexibility from full standby capacity.

 

11. Clarify CIP, Spare Parts and Supply Boundaries

Confirm whether “CIP included” means a complete cleaning package or only connection points.

Review the cleaning tank, pump, filter, piping, materials and isolation arrangement. The package must suit the membrane configuration; tank volume alone does not establish cleaning capability. See How to Size a CIP System for an Industrial RO Plant for related considerations.

For spare parts, request quantities and model numbers instead of an undefined “one-year spare parts package.”

Finally, identify whether the price includes:

• • Raw-water and product-water tanks.

• • Interconnecting pipes and cables.

• • Initial chemicals and commissioning consumables.

• • Installation, commissioning and training.

Clearly mark customer-supplied items and connection boundaries. This makes missing scope visible before purchase.

 

12. Agree on Testing, Documentation and Support

Performance guarantees should have an agreed verification procedure.

Define the test conditions, duration, measurement points, instrument accuracy and acceptance criteria. Also establish how deviations from the design basis will be handled and what happens if performance does not meet the agreed requirements.

Distinguish Factory Acceptance Testing (FAT) from Site Acceptance Testing (SAT). Factory tests may verify assembly, leakage and control functions without reproducing the actual site feedwater.

Request the technical documents needed for operation and maintenance, including:

• • Process and instrumentation diagrams.

• • Layout drawings and utility requirements.

• • Electrical drawings and instrument schedules.

• • Operating and maintenance manuals.

• • Agreed controller backups and restoration instructions.

• • Commissioning records and training deliverables.

Compare warranty coverage and exclusions alongside its duration. Confirm remote versus on-site support, response arrangements and responsibility for travel or service costs.

 

Build a Comparison Table Before Ranking Prices

Record each supplier’s response against the same requirement.

Comparison Field	What to Record
Project requirement	The common specification issued to all suppliers
Supplier’s offer	The quoted model, value, function or service
Supporting evidence	Quotation reference, drawing, datasheet or design projection
Deviation or exclusion	Any difference from the required scope
Status	Confirmed, pending clarification or not included
Additional cost	Cost of bringing the offer to an equivalent scope

Resolve critical technical uncertainties first. Then compare the price of equivalent installed scope and the assumptions behind operating costs.

The strongest quotation is one that clearly connects your water requirements to the proposed equipment, supply responsibilities and acceptance criteria.

 

Request a Clearly Defined Industrial RO Quotation

Planning an industrial RO project? Send Zhongnuo Water Treatment your raw-water analysis, hourly and daily water demand, target product-water quality, operating schedule and site conditions.

These details help our engineering team prepare a quotation with a defined design basis, itemized equipment scope and measurable performance requirements, making supplier evaluation more straightforward.