Lift Station Pump Clogs: What Causes Them and How to Reduce Them

The pump clogs.

Someone pulls it.

The obstruction is removed.

The pump goes back into service.

Then it happens again.

Repeated lift station pump clogs are a sign that it may be time to look beyond simply clearing the obstruction.

Wastewater pumping is demanding because the material entering the system can vary significantly from one day to the next.

The pump may have to deal with solids, grease, fibrous material and items that were never intended to enter a wastewater system at all.

What Causes Lift Station Pump Clogs?

There is rarely one universal answer.

Repeated clogging can be related to what is entering the wet well, how solids are accumulating, pump condition or changes in system operation.

Wipes and Fibrous Material

Wipes, rags and similar materials are a major challenge for wastewater pumps.

Fibres can wrap around rotating components rather than passing cleanly through the pump.

More material becomes caught.

Eventually a relatively small amount of debris can become a much larger mass.

The result is often called ragging.

Removing it gets the pump running again.

But unless the underlying conditions change, another blockage may follow.

Grease and Fats

Fats, oils and grease can also accumulate within wastewater systems.

When they combine with wipes and fibrous material, the result can be particularly difficult for pumping equipment.

The pump may be experiencing conditions very different from what was expected when the system was originally designed.

Solids Settling in the Wet Well

Material does not always remain suspended in wastewater.

Solids may settle and collect.

If enough material accumulates, the pump may eventually receive a much heavier concentration of debris during certain operating cycles.

Wet-well condition should therefore be part of the investigation when clogging becomes repetitive.

Changing Pump Operation

Has anything changed recently?

A new control strategy?

Different pump speeds?

Modified piping?

Changed level settings?

A different pump?

Changes in system operation can affect flow patterns and pump performance.

If lift station pump clogs began after a modification, that timing matters.

Look at Runtime Before the Pump Clogs

Runtime can provide an early clue.

Suppose a pump historically lowered the wet well from the start level to the stop level in a consistent amount of time.

Then cycles gradually become longer.

The pump still works, but it takes more time to move the same amount of wastewater.

That change may indicate developing restriction or reduced performance.

Track it.

Compare Pumps in a Duplex System

If the station contains two pumps, compare them.

Does one pump clog repeatedly while the other rarely does?

Check whether both pumps have similar runtime, operate at similar speeds and alternate correctly.

Also compare their mechanical condition.

A difference between the two pumps can provide an important clue.

When Both Pumps Keep Clogging

If both pumps experience the same problem, look beyond the pumps.

What has changed upstream?

Has a new tenant or process connected to the system?

Has grease loading increased?

Are wipes or other unsuitable materials entering the wastewater?

Sometimes the pump is simply where a much larger system problem finally becomes visible.

Record What You Find

When a clog is cleared, take note of the material removed.

Was it wipes?

Rags?

Grease?

String-like fibres?

Construction debris?

Unknown solids?

Photographs and maintenance records can help establish patterns over time.

Also document which pump clogged, recent runtime, overload trips, high-level alarms and any unusual system behaviour leading up to the event.

Don't Just Clear the Clog

An occasional obstruction can happen in a demanding wastewater application.

Repeated lift station pump clogs deserve a closer look.

Constantly removing debris and returning the pump to service may keep the station operating temporarily, but it does not explain why the same failure keeps happening.

The goal should be to move from responding to clogs to understanding what is causing them.

Academy Pump & Motor provides commercial and industrial pump sales, troubleshooting, service and repair throughout Calgary and surrounding areas.

If your lift station or wastewater pump keeps clogging, Academy Pump & Motor can help investigate the pump and the conditions surrounding it.

Call Academy Pump & Motor at 403-437-7888 or visit academypump.ca.