Best Guide: Key Parameters That Must Be Recorded and Checked During Daily RO System Operation| Insights by AQUALITEK

1. Why Daily Monitoring of RO Parameters Is Essential

A well-maintained RO system delivers stable water quality, lower operating costs, and longer membrane life. Without regular monitoring:

•Fouling and scaling worsen

•Chemical usage increases

•Energy consumption rises

•Membranes fail prematurely

Daily parameter recording is the foundation of predictive maintenance, helping operators detect early warning signs and prevent system downtime.

2. Key Parameters to Monitor Daily in RO System Operation

Below are the essential parameters every RO operator should check and record:

(1) Feed Water Pressure (Influent Pressure)

Indicates the pressure supplied to the RO system from the pretreatment stage.

Why it matters:

•Low feed pressure = insufficient permeate flow and unstable operation

•Sudden drop = clogged filters, malfunctioning pumps

•Sudden rise = fouled pretreatment (e.g., sand filter, cartridge filter)

(2) RO Operating Pressure (High-Pressure Pump Output)

The pressure across the membrane modules during operation.

Why it matters:

•Higher-than-normal pressure → membrane fouling or scaling

•Lower pressure → pump failure or system leak

•Trend analysis helps predict membrane cleaning schedules

(3) Permeate (Product Water) Flow Rate

Volume of purified water produced per hour.

Why it matters:

•Declining flow = fouling, scaling, or membrane degradation

•Basis for calculating recovery efficiency

A stable RO system has gradual, predictable flow behavior—not sudden drops.

(4) Concentrate Flow Rate (Wastewater Flow)

Water that carries rejected salts and impurities out of the system.

Why it matters:

•Imbalanced flow rate affects recovery rate

•Low concentrate flow increases scaling risk

•High concentrate flow reduces efficiency

(5) Recovery Rate (%)

Formula:
Recovery = Permeate Flow ÷ Feed Flow × 100%

Why it matters:

•Too high recovery increases scaling and fouling

•Too low recovery increases water waste and cost
Maintaining the designed recovery keeps the system stable.

(6) Conductivity / TDS of Permeate Water

Indicates the salt rejection performance of the membrane.

Why it matters:

•Rising TDS = membrane failure or damage

•High chlorine exposure or oxidation causes sudden TDS spikes

•Helps determine when membranes need replacement

(7) Feed Water Conductivity / Salinity

Reflects salt load entering the system.

Why it matters:

•High feed conductivity means higher osmotic pressure

•RO requires more energy to maintain performance

•Greatly influences flux, product water quality, and overall design

(8) Differential Pressure Across the RO Stages (ΔP)

Measures pressure drop from inlet to outlet of a membrane stage.

Why it matters:

•Increasing ΔP = fouling or blockage

•Sudden changes point to biological fouling or scaling

•Key indicator for when to perform CIP (clean-in-place)

(9) pH of Feed Water

Important for scaling and corrosion control.

Why it matters:

•Incorrect pH accelerates fouling

•pH affects antiscalant performance

•Extreme pH damages membranes

(10) Temperature of Feed Water

Affects membrane permeability.

Why it matters:

•Higher temperature → more permeate

•Lower temperature → lower permeate
For consistent performance, most systems use temperature correction factors.

(11) Cartridge Filter (Security Filter) Pressure Drop

Measured before and after the 5μm or 1μm cartridge filters.

Why it matters:

•High pressure drop = clogged filters

•Causes lower feed pressure and increased pump load

Replacing filters on time protects upstream RO membranes.

(12) Chlorine Level (if applicable)

Measured upstream of activated carbon.

Why it matters:

•RO membranes (polyamide) are chlorine-sensitive

•Residual chlorine causes irreversible oxidation damage

Even trace chlorine can destroy an entire membrane array.

(13) Antiscalant Dosing Rate

Important for preventing scale formation.

Why it matters:

•Too low = scaling risk

•Too high = chemical waste and higher cost

Daily verification keeps dosing accurate and effective.

3. Recommended Daily RO Monitoring Checklist

A good RO operator records these parameters at least once per shift / daily depending on industry requirements.

4. Summary: Daily Monitoring Protects Your RO System

Monitoring these key parameters helps factories:

•Detect fouling early

•Maintain stable production

•Extend membrane lifespan

•Reduce chemical and energy consumption

•Avoid costly downtime

A disciplined monitoring routine is the best investment in RO system health.