Scale forms where water evaporates rather than drains, and a shower head is the perfect place for that. Each nozzle holds a drop after the water stops; the drop dries; what was dissolved in it stays.
Why heat makes it worse
Calcium carbonate is less soluble in hot water than in cold, so hot water deposits more of it. That is why a kettle furs and a cold tap does not.
Why the nozzles matter
Heads with flexible silicone or rubber cones let the deposit be rubbed off with a thumb, and it comes away as powder. Heads with drilled metal or hard plastic faces do not, and they have to be soaked in descaler — which is a problem on coloured or coated finishes, where the manufacturer usually forbids acidic products.
What actually prevents it
Nothing at the head. A softener treats the water before it arrives; everything else is maintenance. Wiping a head after use removes the drop before it can dry, and that is the whole of the free option.
What to check when buying
Whether the nozzles are cleanable, and whether the maker sells a replacement face.
This does not replace the manufacturer's own instructions. Every dimension, thread size, flow rate, operating pressure, water seal depth and load figure on this page is reported from the manufacturer's own documentation, with its unit written as published, and named as such — none of it is measured here. A flow rate is reported with the pressure the manufacturer measured it at, and is never converted to another pressure, because no conversion exists. And the second statement repeated rather than assumed: a water softener treats limescale and is not a health product — softened water carries more sodium, not less. A filter reduces what its manufacturer declares it reduces; no benefit for skin, hair or health is claimed here, and drinking water quality is a matter for your supplier.
Questions people actually ask
Can I soak a shower head in vinegar?
On a plain chrome head, that is the usual domestic method. On a black, brushed, gold or coated finish, check the manufacturer's instructions first — most state that acids must not be used, and the damage is permanent.
Do the magnetic or electronic anti-scale devices work?
This site does not publish a verdict on them, because the evidence a comparison page could honestly cite does not exist. What can be compared are ion-exchange softeners, whose mechanism and capacity are stated and measurable.
Last reviewed 5 September 2026