Fleck 18928 5600/4600 Filter Piston assembly for backwashing systems

The Fleck 18928 filter piston is the genuine replacement piston for Fleck 5600 and 4600 valves configured as backwashing filters — such as carbon, sediment or iron filter systems — rather than softeners, and WrekinWater supplies it to help owners resolve backwash cycle faults without replacing the whole filter valve.

Technical specifications

Symptoms that mean you need this part

• The filter failing to trigger or complete a backwash cycle on schedule
• Water running continuously to the drain line outside of a backwash
• Reduced flow or pressure through the filter during normal service
• The valve sticking, grinding or stalling partway through the backwash sequence

Why it fails / why it matters

Unlike a softener piston, the filter piston in a 5600 or 4600 backwashing configuration only needs to manage service, backwash and rinse ports, since there's no brine draw stage, but it's still subjected to the same constant flow and mineral exposure that gradually wears its sealing surfaces. Sediment, iron and manganese being filtered out of the water are exactly the contaminants most likely to abrade or clog the piston over time, so filter pistons on iron and sediment removal systems often need replacing more frequently than the equivalent softener piston.

Why buy this from WrekinWater

WrekinWater has served more than 50,000 customers over 15 years and, from its base in Bettisfield, Shropshire, stocks genuine parts for Fleck, Autotrol, Clack, Kinetico and other major brands, including the specific 18928 filter piston needed for backwashing filter configurations rather than softener valves. As a UK company (No. 11000488) rated Excellent on Trustpilot, WrekinWater helps filter owners keep their systems backwashing correctly and avoid a drop in filtered water quality.

How to fit it

1. Shut off the water supply to the filter and place the valve into bypass
2. Release pressure from the valve body before opening it
3. Remove the valve cap and withdraw the existing filter piston assembly
4. Inspect the valve bore, seals and spacers for scale, iron staining or wear and clean as needed
5. Fit the new Fleck 18928 filter piston, lubricating lightly with a food-safe lubricant
6. Reassemble the valve, restore the supply, come off bypass and run a manual backwash cycle to confirm correct operation