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PUREFLOW BIO / ENGINEERING FIELD GUIDE

Drum filter troubleshooting. Clarity starts here.

Drum filter troubleshooting guide: why a drum keeps rinsing, will not rinse, will not turn, leaks, overflows or leaves the water cloudy, with a step by step fix order and a maintenance routine.

Explore the process ↗Start fault diagnosis
14 MIN GUIDEUPDATED NOVEMBER 2026
Pureflow RDF-50 product illustration showing the drum screen and spray nozzlesEQUIPMENT REFERENCE
Equipment reference illustration. Confirm the supplied model configuration and installation arrangement from its approved documentation.
01Understand the mechanismInspect the relevant process stages.
02Review the operating dutyKeep assumptions and measured values visible.
03Prepare the next decisionUse the guide, tools and project checks.
INTERACTIVE PROCESS ATLAS

See the mechanism.
Understand the duty.

Select a route or a stage to inspect the process. The cutaway explains the equipment and water environment; it is a teaching illustration, not a project drawing.

Swipe horizontally to inspect the equipment. Stage buttons below also centre the selected component.
Rotary drum screen and separate waste routePUREFLOW / INTERACTIVE PROCESS ATLASCONCEPT LAYOUT · NOT TO SCALECULTURE WATERSCREEN + SPRAY + DRIVEDOWNSTREAM BIOLOGYWASH WASTE OUTWASH SUPPLYMotion explains the process; it is not a measured flow rate or biological time model.
Follow water across the screen and toward the downstream treatment. The line speed is illustrative.
Selected process stage

Capture solids

Use actual flow, screen opening and solids duty.

How it works

Particles are retained as water crosses the screen. Dissolved contaminants require other treatment stages.

What to establish
  • Use actual flow, screen opening and solids duty.
  • Confirm approved levels, wash supply and waste drainage.
  • Observe a complete guarded cycle before changing settings.

Continue this guide ↗

Filtration mode. Wash sequence and timing are illustrative. Geometry, stage order, pipe routes and equipment configuration are conceptual. Use the approved project design, operating instructions and verified model data.
01 / GUIDED DIAGNOSIS

What is your filter
telling you?

Select a symptom, choose your installation type, then answer the first diagnostic question. Use the full guide for the detailed checks.

Protect the stock before hands-on work.

Maintain oxygen and follow the emergency circulation plan. Isolate supplies and release wash-line pressure before reaching into equipment.

Read the stop conditions ↗
DIAGNOSTIC WORKSPACEOBSERVATION → CHECK → NEXT ACTION
Select the symptom
CONTINUOUS RINSING / FIRST CHECK

Does one complete wash leave the screen clean?

Pump-fed: inspect a dirty-side rise and the downstream outlet route. Use your commissioned operating levels.

Choose an answer above. Observe only with guards secured and hands clear; follow the model’s operating instructions.
Open the continuous rinsing guide
A diagnostic route, not a confirmed fault diagnosis. Electrical work, drive adjustments, UV servicing and internal repairs require the appropriate qualified service personnel.
02 / SYMPTOM → CAUSE → ACTION

The fault library.

Focused guides with possible causes, observable checks and the next action. Expand a guide or search for a component.

9 fault guides
01

Continuous rinsing

The wash repeats, but normal operation does not return.

Use the checks below with the approved commissioning settings for your installation. Isolate before inspection or maintenance; observe powered tests only from a safe position with guards secured.

Panel too fine for the load
Count rinses per hour and compare with the feed rate
Review screen selection and loading with Pureflow before changing mesh; protect downstream treatment and stock.
Screen blinded by fat or biofilm
Look at the screen after a rinse
Use the approved cleaning procedure with compatible water and a soft brush.
Blocked or weak nozzles
Check the spray pattern
Clear the tips and check the pump pressure
Heavy feeding or leaf load
Check the debris on the screen
Add a net or skimmer ahead of the inlet
Sensor mounting or sensing surface incorrect
Check the probe height and clean it
Clean after isolation; restore the approved mounting position. Do not guess a new trigger level.
Inflow higher than the model rating
Compare the real flow with the catalogue
Reduce the flow, or step up a model
Recovery check / A complete wash restores the commissioned water levels and does not immediately retrigger under unchanged loading.
02

No automatic rinse

The screen loads, but the cleaning cycle does not start.

Use the checks below with the approved commissioning settings for your installation. Isolate before inspection or maintenance; observe powered tests only from a safe position with guards secured.

No power at the control box
Check the supply, breaker and fuse
Confirm the cause of any trip with a qualified electrician before restoring power.
Level sensor stuck or dirty
After isolation, clean the sensor using the supplied procedure and check its approved mounting.
Clean or replace the sensor
Rinse pump failed or air locked
Listen for the pump and check the strainer
Follow the pump’s priming procedure after checking supply and suction conditions; arrange service if the fault remains.
Timer or setting wrong
Check the control box settings
Compare with the recorded commissioning values; do not guess new settings.
Rinse line closed
Check valves on the spray line
Open the valve and test
Wiring fault or damaged cable
Inspect the cable and plugs
Keep the equipment isolated; have damaged electrical parts assessed and replaced by a qualified technician.
Recovery check / The approved automatic trigger initiates and completes a cycle without an alarm.
03

Weak or uneven spray

The drum washes, but dirty stripes remain.

Use the checks below with the approved commissioning settings for your installation. Isolate before inspection or maintenance; observe powered tests only from a safe position with guards secured.

Clogged spray nozzles
Look for tips that spray weakly or not at all
Remove and rinse only as instructed. Use a soft brush; do not enlarge the orifice with wire, needles or drills.
Dirty pump strainer
Open and inspect the strainer
Clean it out and refit
Worn rinse pump
Compare measured pressure and supply conditions with the pump manufacturer’s operating data.
Service or replace the pump
Air in the suction line
Look for bubbles and loose fittings
Tighten the joints and bleed the line
Spray bar misaligned
Check the angle of the bar against the screen
Have alignment restored to the approved position; nozzle angle and clearance are model-specific.
Fat or limescale on the screen
After isolation, inspect for grease, scale and biofilm without damaging the mesh.
Use the approved screen-cleaning procedure and compatible materials.
Recovery check / The observed nozzle pattern is even and the washed screen is consistently clear.
04

Screen fouling

Grease, biofilm or mineral deposits restrict the mesh.

Use the checks below with the approved commissioning settings for your installation. Isolate before inspection or maintenance; observe powered tests only from a safe position with guards secured.

Fat from feed
Greasy film that beads water
Use only a cleaner approved for the mesh, frame, seals and aquatic system; prevent residues returning to stock.
Biofilm
Slimy brown or green layer
Use compatible rinse water and a soft brush; keep residues separate from stock.
Limescale
White, crusty deposit
Obtain the approved descaler, concentration and contact time for all wetted materials; isolate from fish and biofilters and rinse fully.
Algae in sunlight
Green growth on exposed parts
Shade the drum, then clean the panel
Recovery check / Approved cleaning restores permeability without mesh or support damage.
PUREFLOW / ROTARY DRUM FILTERINSPECTION GUIDE
Pureflow RDF-50 product illustration showing the drum screen and spray nozzles
Understand the whole system.Screen. Wash. Control. Drive.
RDF-50 illustration
Configuration varies by model.
05

Overflow or level drop

The dirty side rises, or the clean side loses water.

Use the checks below with the approved commissioning settings for your installation. Isolate before inspection or maintenance; observe powered tests only from a safe position with guards secured.

Screen blinded
Check the screen and the rinse rate
Deep clean the screen
Waste line blocked or frozen
Check the drain
Clear the line and protect it from frost
Inlet flow above the rating
Compare the flow with the model rating
Reduce flow or step up a model
Outlet restricted
Check the outlet valves and pipes
Restore the approved outlet route; do not alter valves needed for stock protection.
Bypass or leak in the chamber
Look for water paths around the drum
Have the sealing arrangement assessed; use compatible parts and the approved repair method.
Recovery check / Operating levels remain within the approved range without overflow or pump starvation.
06

Drum not turning

The wash runs, but the drum remains stationary.

Use the checks below with the approved commissioning settings for your installation. Isolate before inspection or maintenance; observe powered tests only from a safe position with guards secured.

No power to the motor
Check the supply and motor protection
Have a qualified technician establish the cause of a protection trip before restarting.
Worn or broken drive gear
Inspect the gear teeth
Replace the gear
Seized bearing
Inspect after full isolation. Do not force the drum or back-drive the gearbox; follow the drive instructions.
Arrange bearing assessment and confirm the replacement specification.
Foreign object jamming the drum
Look for debris between drum and housing
Remove the object
Motor fault
Listen for a hum without movement
Service or replace the motor
Overloaded drum
Check how much solid is on the screen
Clean the screen and rinse again
Recovery check / The drum moves normally during a guarded test without a stall or rubbing.
07

Unusual noise

A new rattle, scrape, hum or grinding sound.

Use the checks below with the approved commissioning settings for your installation. Isolate before inspection or maintenance; observe powered tests only from a safe position with guards secured.

Dry or worn bearing
Listen for a squeal or grind
Use only the specified maintenance procedure; sealed bearings may not be serviceable. Arrange assessment if rough or loose.
Loose fastener
Check bolts and covers
Tighten them
Pump cavitation
Check the suction line and strainer
Clear blockages, reduce restrictions
Rubbing drum
Inspect clearances after full isolation; manual movement requires the approved drive procedure.
Re-align or replace the worn part
Worn gear
Inspect the gear teeth
Replace the gear
Recovery check / The source is identified and the abnormal sound does not return during a guarded test.
08

Water leaks

Water appears at joints, seals or the housing.

Use the checks below with the approved commissioning settings for your installation. Isolate before inspection or maintenance; observe powered tests only from a safe position with guards secured.

Worn seal
Look for drips at the drum seal
Replace the seal
Loose pipe joint
Check the fittings
Tighten or reseal them
Overflow from a blocked drain
Check the waste line
Clear the drain
Cracked housing
Inspect the housing
Repair or replace the part
Recovery check / The source stays dry throughout filling, filtration and a complete wash.
09

Cloudy or green water

Particles, algae or biological conditions need investigation.

Use the checks below with the approved commissioning settings for your installation. Isolate before inspection or maintenance; observe powered tests only from a safe position with guards secured.

Panel too coarse
Compare the haze with the micron rating
Identify the particles first; confirm finer mesh availability and its effect on flow, wash rate and downstream duty.
Torn or damaged screen
Look for holes or loose edges
Replace the panel
Green water algae
Check the water colour
Investigate suspended algae; review UV condition, flow, water clarity and treatment duty. Mechanical screening alone may not remove fine algae.
Biofilter overloaded
Check ammonia and nitrite
Check oxygen, pH, alkalinity, loading and biofilter maturity; arrange biological-duty review before adding equipment.
Flow too high
Compare the flow with the rating
Reduce the flow or step up a model
Heavy feeding
Check the feed rate
Feed less and clean the screen
Recovery check / Assess the diagnosed cause with water-quality tests and an appropriate observation period.

Before changing the mesh: check actual flow and solids loading. Catalogue maximum flow is a comparison value, not a guaranteed operating duty at every mesh and load. Review drum filter sizing ↗

03 / UNDERSTAND THE SYSTEM

Seven places.
One connected process.

A fault in one part can appear as a symptom somewhere else. Select an inspection point to see its role and what to observe.

01 / Filter panel

Inspect for deposits, tears, loose edges and damaged support after isolation. Persistent haze alone does not prove that the panel is worn.

The drawing is a process concept. Component positions, flow routes, level sensing and protection logic depend on your model and installation.

PUREFLOW / PROCESS CONCEPTRDF + WASH SYSTEM
INLETOUTLETCONTROLWASTEWASH SUPPLY1234567

Simplified concept, not to scale. Confirm actual component locations from the supplied drawing.

01

Capture

Mesh retains suspended particles as water passes through.

02

Detect

The configured level signal or timed control requests cleaning.

03

Rotate & wash

The drive moves the screen while the wash system clears retained solids.

04

Remove waste

The gutter takes retained solids and wash water to the waste route.

05

Recover

Check that the wash ends and approved operating levels return.

04 / PREVENT THE NEXT STOP

A routine you
can work through.

Use this checklist during an operating review. The exact frequency and service procedure follow your manual, loading and site conditions.

0 of 12 review items checked

Checks stay only in this page session. Use the service record at your site for permanent maintenance evidence.

Observe each operating dayAdjust to site loading

Inspect during planned serviceIsolate before hands-on work

Review before high-load periodsFeeding, rain and seasonal debris

Arrange the periodic serviceUse manufacturer instructions

01 / ISOLATE

Prevent an automatic restart.

Secure all relevant supplies, including separately fed pumps or UV equipment. Release trapped wash pressure. A controller OFF button may not isolate mains power.

02 / STOP CONDITIONS

Know when to call service.

Smoke, burning smells, electrical moisture, exposed wiring, a stalled drive or repeated tripping require isolation and qualified diagnosis. Never bypass a protective interlock.

03 / PROTECT THE STOCK

Plan the outage.

Maintain oxygen and the approved emergency circulation arrangement. A bypass may only be used if the installation and downstream process were designed for it.

05 / MEASURE, THEN DECIDE

Know your actual
backwash water use.

A changing wash rate is useful evidence. Measure several complete cycles, record a daily cycle count, and calculate the water used at your installation.

Measured litres ÷ test cyclesLitres per cycle × daily cycles = estimated litres per day

Use a wash-water supply meter where available. Total waste discharge may include process water as well as wash water, so record the measurement point.

These results come from your measurements. They are not guaranteed Pureflow model ratings. Arrange measurement without blocking the drain or approaching moving equipment.
—LITRES / CYCLE
—LITRES / DAY
Enter your measurements to calculate. No default operating values are assumed.
06 / SERVICE & REPLACEMENT

Clean, service
or replace?

Order by model, serial number and part revision. Appearance alone does not establish compatibility.

COMPONENT / 01

Screen panel

Observe
Deposits without structural damage
Check first
Use the approved cleaning procedure. Review permeability after cleaning.
Service decision
Tears, damaged support or loose mounting require replacement assessment.
COMPONENT / 02

Nozzles & spray bar

Observe
Uneven fan, blocked tip or leak
Check first
Clean without changing the orifice; confirm bar alignment.
Service decision
Replace worn or cracked components with the matching specification.
COMPONENT / 03

Sensor & mounting

Observe
Erratic signal or fouled sensing surface
Check first
Clean, check mounting and have the input signal tested.
Service decision
Confirm failure before replacing the sensor or controller.
COMPONENT / 04

Wash pump

Observe
Poor spray, air ingress, noise or tripping
Check first
Review supply, suction and strainer before condemning the pump.
Service decision
Arrange service for persistent loss of performance or electrical faults.
COMPONENT / 05

Drive, bearings & seals

Observe
Rubbing, play, leakage or abnormal noise
Check first
Use only specified adjustment and lubrication procedures.
Service decision
Do not force the drum; have damaged drive parts assessed.
COMPONENT / 06

Electrical & UV equipment

Observe
Moisture, damage, trip or burning smell
Check first
Keep the affected equipment isolated and record the fault.
Service decision
Qualified service must establish a safe repair and restart.

Keep a record of the date, symptom, operating levels, flow, wash frequency and work completed. Check repairs through a full operating and wash cycle before returning to unattended use.

07 / CLEAR ANSWERS

The questions
operators ask.

Short answers for the next decision. Use the detailed fault guides and your model instructions for the actual service procedure.

Ask Pureflow
Why does my drum filter keep rinsing?

Check whether one complete wash clears the screen and restores the operating level. If it does not, inspect the nozzles, wash-water supply, drum movement and deposits. If it does, review solids loading, actual flow, outlet restrictions and the sensor signal before changing mesh or settings.

How often should a drum filter rinse?

There is no universal interval. Compare the wash frequency with your commissioned baseline at similar flow and feeding. A sustained increase or a cycle that fails to restore levels needs investigation.

Why is my drum filter not rinsing?

Record the external controller indication. If the model has a manual wash control, test it only with guards secured and hands clear. A successful manual cycle directs attention to the automatic sensor and control input; no response requires supply and controller diagnosis by qualified service personnel.

Why is my drum filter overflowing?

In a pump-fed layout, check screen permeability, effective washing, actual inlet flow and downstream outlet restrictions. In a gravity-fed layout, check for clean-side drawdown and restricted gravity supply. Also inspect waste drainage if the wash gutter backs up.

How do I clean a drum filter panel?

Isolate power and wash pressure, separate the cleaning route from stock and biological filtration, and follow the approved screen procedure. Use a soft brush and compatible rinse water. Obtain approval for any chemical, concentration and contact time; rinse completely before returning to service.

How long does a drum filter panel last?

There is no verified fixed replacement interval for every Pureflow installation. Inspect for tears, damaged support, loose attachment and persistent blockage after approved cleaning. Confirm the correct replacement panel using the model and serial number.

How much water does a drum filter use for rinsing?

Measure the wash-water volume over several complete cycles and divide by the number of cycles. Multiply litres per cycle by the recorded daily cycle count to estimate litres per day. Total waste-drain discharge may also include process water, so identify the measurement point. No universal Pureflow litres-per-cycle value is claimed here.

Should I switch off my drum filter in winter?

Follow the operating plan for the stocked system. Where freezing is possible, protect the wash supply, pump and waste drain. A planned shutdown must include an alternative oxygen and water-treatment plan, plus draining and storage steps specified for the equipment.

Can I run the drum filter while I fix a fault?

Do not work on moving or pressurised equipment while it is energised. Maintain stock protection using the approved standby or emergency arrangement. Use a bypass only if the installation was designed for it and downstream treatment can accept the resulting water quality.

When should I call for help?

Call immediately for repeated trips, electrical moisture, smoke, burning smells, a stalled drive or uncontrolled water loss. Also seek support when cleaning and hydraulic checks do not resolve the fault. Supply the model, serial number, alarm, water levels and a safe video.

How do I know if my drum filter needs a new screen?

Visible tears, loose edges or damaged supports justify inspection for replacement. Persistent fouling may require a cleaning review, while haze can have biological or particle-size causes. Hazy water alone does not prove that the screen is worn.

08 / TECHNICAL SUPPORT

Give us the evidence.
We’ll help with
the next step.

A useful service brief is more valuable than a guessed replacement part. Prepare the details below and share them with Pureflow.

  • Model, serial number and controller alarm text.
  • Installation type, actual flow and operating water levels.
  • What changed before the fault and what you have checked.
  • A short video from a safe position, with guards secured.
WhatsApp support ↗Contact Pureflow

Call +91 98444 11881
WhatsApp +91 98455 91881

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