How to Clean a Doulton Ceramic Water Filter

One of the most practical advantages of Doulton ceramic filter candles is that they can be cleaned and reused multiple times when flow rate declines, unlike standard carbon or sediment cartridges that must simply be discarded.

Doulton's guidance states that a ceramic candle can be cleaned up to approximately 50 times over its service life. Understanding the correct cleaning technique -- and just as importantly, what not to do during cleaning -- ensures the candle continues delivering its rated 0.9-micron absolute filtration performance after each cleaning cycle.

Why Doulton Ceramic Candles Need Cleaning

A Doulton ceramic candle works by filtering water through the microscopic pores of the diatomaceous earth ceramic shell. As water passes through, particulate contaminants, sediment, and biological material accumulate on the outer surface of the candle, gradually blocking the pores and reducing flow rate.

This surface loading is entirely normal and is the sign that the filter is working -- but once flow rate has dropped noticeably, cleaning removes the loaded outer ceramic layer and restores the pore surface.

This is a physical surface process. Cleaning removes the outermost layer of the ceramic, along with the particles it has captured, and exposes a fresh ceramic layer underneath. With each cleaning, the candle diameter decreases slightly. When the diameter has reduced by approximately 5mm from its original measurement, the candle is approaching the end of its structural life and should be replaced.

What You Will Need

A clean Scotch-Brite pad, soft nailbrush, or clean toothbrush. Clean running cold tap water. Clean, dry hands. Nothing else -- no soap, no detergent, no bleach, no vinegar, no hot water.

The silver impregnated throughout the ceramic body provides bacteriostatic protection against microbial growth within the candle. Soap, detergent, and bleach all potentially interfere with this silver protection layer and should never be used on a Doulton ceramic candle.

How to Clean a Gravity System Ceramic Candle (Doulton / British Berkefeld)

Step 1 -- Empty the upper chamber. Pour out or drain the unfiltered water from the upper chamber of the gravity system before removing the candles.

Step 2 -- Remove the candle. Turn the upper chamber over or access the candles from inside. Unscrew the plastic wing nut that secures the candle to the chamber base -- counterclockwise.

The candle lifts straight out. Handle the candle body only -- do not touch the threaded fitting at the top (the clean-water end) with bare hands or allow unfiltered water to contact it. Keep the clean-water end pointing upward and away from the dirty water side.

Step 3 -- Clean the ceramic surface. Hold the candle under gently running cold water. Using the Scotch-Brite pad or soft brush, scrub the outer ceramic surface using uniform circular strokes with light pressure. The goal is to remove the loaded outer layer evenly around the entire surface. Work systematically from top to bottom.

You will see the ceramic lighten slightly as the loaded layer is removed. Do not scrub aggressively -- firm, consistent light pressure is more effective than force and less likely to cause uneven ceramic removal.

Step 4 -- Do not touch the threaded mount. The threaded plastic fitting at the top of the candle is the clean water output end. It must remain free from contamination throughout cleaning. If it is accidentally touched with dirty hands or contacts the unfiltered water side, the candle has been cross-contaminated and must be replaced rather than reinstalled.

Step 5 -- Rinse and inspect. Rinse the candle under running water after scrubbing. Inspect the surface -- it should appear uniformly clean with no remaining dark loading. Measure or visually assess the diameter; if the candle has become noticeably thinner (more than 5mm reduction from original), it is approaching the end of its structural service life.

Step 6 -- Reinstall and prime. Thread the candle back onto the chamber base, tighten the wing nut by hand until snug (do not overtighten), and discard the first full chamber of filtered water after cleaning to flush any ceramic dust released during the scrubbing process.

Cleaning Undersink Doulton Ceramic Candles

Undersink Doulton candles (Sterasyl, Super Sterasyl, UltraCarb) follow the same cleaning process, but removal requires depressurizing the under-sink housing first:

Shut off the water supply to the housing, press the pressure relief button if present, unscrew the housing sump, and remove the candle from the sump. Clean the ceramic exterior as described above under running cold water. Reinstall in the housing, confirm the wing nut and rubber sealing washer are properly seated, and restore the water supply.

The Critical Distinction: Pure Ceramic vs. Multi-Stage Candles

This is the most important point for anyone maintaining a Doulton system with multi-stage candles. Pure Sterasyl candles (ceramic only) can have their full filtration performance restored by cleaning because there is no internal media to exhaust -- the ceramic is the entire filter.

Multi-stage candles like the UltraCarb, ATC Super Sterasyl, and W9121226 contain granular activated carbon and heavy metal reduction media inside the ceramic shell. Cleaning the exterior removes the loaded ceramic surface layer and restores flow rate and biological filtration, but it does not regenerate the internal carbon or heavy metal media. These candles should be replaced on the 6-month or 400-gallon schedule regardless of how many times the exterior has been cleaned.

The Doulton W9121226 Ultra Sterasyl gravity candle is the standard multi-stage candle for British Berkefeld gravity systems, rated for 6 months or 400 gallons per candle. The full Doulton ceramic water filters collection at DFS covers replacement candles for gravity and undersink systems across all current Doulton candle types. For the gravity filtration systems themselves, the gravity filtration systems collection includes Doulton, British Berkefeld, and USWF systems.

Questions about Doulton ceramic candle maintenance or replacement? Call the DFS team at 1-800-277-3458.

Frequently Asked Questions

How do I clean a Doulton ceramic water filter candle?

Remove the candle from the system and hold it under gently running cold water. Using a soft Scotch-Brite pad or clean brush, scrub the outer ceramic surface using light, uniform circular strokes to remove the loaded outer layer. Do not use soap, detergent, bleach, or hot water. After scrubbing, rinse thoroughly, discard the first chamber of filtered water after reinstalling, and return the system to normal use.

How many times can a Doulton ceramic candle be cleaned?

Doulton's guidance states that a candle can be cleaned approximately 50 times before it needs replacement. Each cleaning removes a thin outer layer of ceramic, slightly reducing the candle's diameter. When the diameter has reduced by approximately 5mm from the original measurement, the candle should be replaced. Never clean a candle to the point where the ceramic shell becomes structurally thin.

Can I use soap or bleach to clean a Doulton ceramic candle?

No. Soap, detergent, bleach, vinegar, and hot water must all be avoided. These substances can interfere with the silver impregnation throughout the ceramic body that provides bacteriostatic protection. Clean running cold water and gentle physical scrubbing are all that is needed and all that should be used.

Does cleaning restore the full filtration performance of a Doulton candle?

For pure Sterasyl candles (ceramic only), yes -- cleaning removes the loaded ceramic surface and fully restores both flow rate and biological filtration performance. For multi-stage candles containing activated carbon inside (UltraCarb, ATC Super Sterasyl, W9121226), cleaning restores flow rate and biological filtration but does not regenerate the internal carbon or heavy metal media. Multi-stage candles should be replaced on the 6-month or 400-gallon schedule regardless of cleaning history.

How do I know when to replace a Doulton ceramic candle rather than clean it?

Replace the candle when: the diameter has reduced by approximately 5mm from the original measurement; the candle has been cleaned approximately 50 times; 6 months or 400 gallons have passed for multi-stage candles; flow rate does not recover meaningfully after cleaning; or the candle has been cracked, chipped, or cross-contaminated by contact between the clean-water end and unfiltered water.

What happens if I touch the threaded end of the candle with dirty hands?

 The threaded plastic fitting at the top of the candle is the clean-water output end. If it is touched with unclean hands or contacts unfiltered water, the candle has been cross-contaminated. A contaminated candle must be replaced -- it cannot be decontaminated by cleaning the exterior. This is the single most important precaution during maintenance.

How do I prime a new Doulton candle before first use?

Flush each new candle under cold running water for 1 to 2 minutes before installation to remove ceramic dust from manufacturing. After installation, discard the first full chamber of filtered water to fully prime the system. This applies both to brand-new candles and to candles after cleaning.