We live in an area with very hard water, and so the usual problems this creates.

One particular thing is that we get a lot of flakes of a chalky material building up in the shower head (We've got an "anti-limescale" shower head that you can dismantle to clean it). The shape and nature of these flakes suggests to me that they're the result of limescale building up inside a pipe somewhere in the system, then flaking off and travelling down the pipes until they get caught up in the shower head.

Is there any way I can work out where this buildup is happening, and stop it? Why does it only happen in the shower, and not in the normal taps?

If it makes a difference, it's an electric shower, wheras the other taps (bath, sink etc) are fed off the gas boiler.

3 Answers 3


A standard water softener will remove most of the calcium ( and Mg, Ba, Sr , etc) from the water supply. It will not remove existing scale in the pipes, etc. It would be expensive to remove the existing scales ; flushing with dilute hydrochloric/muriatic would do it , but not a job for the homeowner. The taps that don't plug may have no strainers; also you may have mostly "temporary" hardness. In temporary hardness , carbon dioxide acidifies the water and keeps the calcium in solution, when the water is heated the CO2 is removed, and then the calcium precipitates/scales.


80% of limestone buildup usually happen at first 2 bend in hot pipe, so if you have easy access to first 2 bend starting from the water heater, you can replace them with new one and stop most of 'flocking'. I sugest to use iron/steel pipes because plastic ones will move buildup to next bends so, if pipe is buiried into concrete, you'll never be able to clean again.

Also if you have an 'instant' (tankless) water heater, I suggest you to set temperature to less than 50°C and add a polyphosphate proportional dosing device. If you have a 'tank' model that kind of device is unuseful because water is kept hot for long times and the chemicals wont work properly.

  1. Put water in a kettle. (If you're in the USA and don't know what a kettle is, use a saucepan instead, with a lid on it).
  2. Boil the kettle and make yourself a cup of tea.
  3. Repeat steps 1 and 2 many times. You'll notice lots of limescale in the kettle. This is because heating water causes limescale to drop out of solution. [citation needed] [but I can't be bothered to find one]

Your heating element in your electric shower heats water. Limescale is forming on your heating element, and then dropping off to come out of / block up your shower head.

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