How to descale a shower head

Inspired by a helpful Which? guide. This walk-through is based on the popular UK video "The best way to descale a shower head" by Which?, the UK consumer organisation. Their testing showed citric acid outperforms white vinegar and bicarbonate of soda for stubborn limescale. Worth watching if you want to see the before-and-after difference on a badly clogged head.

1. Spot the signs of limescale build-up

If the spray has become weak, patchy, or sprays at odd angles, limescale is almost certainly the culprit — especially in Kent and the south-east, where the water is very hard.

Look closely at the nozzles. White or grey crusty deposits around each hole are limescale. Some may be blocked solid. That said, if the whole shower feels weak and the head looks clean, the problem might be pressure or a flow restrictor rather than scale. Rule that out first.

2. Decide which method you need

Detachable shower heads (the kind on a hose) can be unscrewed and soaked in a bowl. Fixed overhead heads need the bag method. Both work well.

For the soaking solution, citric acid is the most effective option. A tablespoon dissolved in about 500ml of warm water is plenty. White vinegar also works, though it smells and takes a bit longer. Avoid bleach — it does not dissolve limescale.

3. Remove a detachable head and soak it

Unscrew the head from the hose by hand, or with a cloth to protect the chrome. Place it face-down in a bowl or container deep enough to fully submerge the face plate.

Pour in enough citric acid solution to cover it and leave it for 20 to 30 minutes. Stubborn build-up may need an hour. You will see the scale beginning to dissolve — little bubbles, discolouration in the water.

4. The bag method for fixed overhead heads

Fill a food bag or freezer bag with the citric acid solution — enough to submerge the face of the shower head when the bag is held up against it.

Lift the bag up around the head so the nozzles are fully submerged, then secure it in place with a rubber band or cable tie around the arm. Leave it for 20 to 30 minutes. Mind you, this is easier with two pairs of hands if the arm is positioned awkwardly.

5. Scrub the nozzles

After soaking, remove the bag or lift the head from the bowl. Use an old toothbrush to scrub each nozzle in a circular motion. Most of the scale should brush away easily now that the acid has loosened it.

For rubber nozzles (common on modern heads), you can flex them individually with your thumb and forefinger to crack any remaining deposits off. Very satisfying.

6. Flush and reattach

Before reattaching a detachable head, run the hose at full pressure for ten seconds to flush out any loose scale still inside the body of the head. Then screw it back on — hand-tight is enough. Use PTFE tape on the thread if there was a drip before.

For fixed heads, remove the bag and turn the shower on at full pressure. Let it run for a minute to flush any loosened material through the system and out of the nozzles.

7. Test the flow and repeat if needed

Turn the shower on and check each nozzle sprays cleanly. The improvement should be immediate and obvious. If a few nozzles are still partially blocked, repeat the soak for another 30 minutes.

To be fair, a very neglected head may need two or three treatments. Severe blockages that do not respond to repeated soaking are a sign the head itself is past its best. Shower heads are inexpensive to replace.

When to call a handyman

Descaling is a DIY job. But if the pressure is low even after descaling, the cause might be a failing shower pump, a partially closed valve, or a flow restrictor in the hose fitting. Call Richard if you are not sure what is causing the problem, or if water is dripping from the arm or connection point after you have retightened everything.