Will raw water flushing of a self-cleaning filter make the water dirtier after cleaning?

A properly designed self-cleaning filter will not become dirtier when flushed with raw water. It only gets dirtier after cleaning due to mismatched working conditions or improper model selection.

Why it normally won’t get dirtier

The cleaning method adopts negative pressure sewage suction + reverse flushing.

It does not filter raw water first for cleaning. Instead, it directly uses the pressure of raw water to perform reverse flushing from the outside to the inside of the filter screen, sucking away filter cake contaminants. The dirt is discharged directly through the drain outlet without remaining in the system.

All intercepted impurities are discharged externally instead of flowing back.

Sediment, suspended solids and algae washed off are instantly discharged out of the equipment via the drain valve, and will not return to the raw water to be filtered.

The filter screen works by physical interception, and cleaning only removes surface dirt.

Although raw water contains impurities itself, flushing only instantly clears contaminants on the screen surface, rather than soaking and polluting the screen with dirty water. The filter restores normal filtration immediately after cleaning.

Situations where it really gets dirtier after cleaning

Too small drain pipe diameter or excessively short sewage discharge time

Dirt cannot be completely drained, and part of it flows back and adheres to the filter screen again.

Extremely high concentration of suspended solids and large amounts of viscous impurities

For water containing abundant colloid, algae, bacteria and oil stains, hydraulic flushing with raw water alone cannot achieve thorough cleaning, resulting in residual scaling.

Excessively high filtration precision of the selected screen

For fine high-precision filter screens, fine particles in raw water tend to embed into the mesh, which cannot be completely removed by simple hydraulic backwashing.

Poor pipeline installation with backflow design

The sewage outlet is connected back to the inlet water tank nearby, causing dirty water to circulate back into the system again.