Hard water
Hard water and limescale: what a filter can do
Hard water carries more calcium and magnesium. It is not a quality problem, it is a limescale problem: in the kettle, on taps, in tea and coffee. Our limescale option adds an extra filtration stage, developed specifically for it.
Updated 14 October 2026
Signs your water is hard
The kettle furs up
A white crust forms inside, sometimes within weeks.
White marks
On taps, shower screens and glasses after they dry.
A film on your tea
Tea and coffee look cloudy or have a film on top.
How hard is your water?
Water companies measure hardness. Your report puts it on 5 levels.
Hardness
Very soft · Soft · Medium · Hard · Very hard
In mg/L as calcium carbonate: very soft under 75 · soft 75 to 150 · medium 150 to 250 · hard 250 to 350 · very hard over 350.
The limescale option: you asked, we developed it
Many of you live with hard water. You told us about kettles that fur up, white marks on taps and glasses, and a film on your tea.
You asked for a filter that also deals with limescale. So we developed a new filtration stage, specifically for it, and built it into our Tap System filters.
How it works
The filtration you chose
Advanced+ filters like Advanced. Nano+ filters like Nano, our most complete filtration. Advanced or Nano?
Plus one stage, just for limescale
An extra stage inside the same filter, developed specifically for limescale.
Less limescale where you see it
The new filter reduces limescale in the kettle, in tea and in coffee.
What you notice
We give no percentage for limescale: what you notice depends on how hard your water is.
Kettle
Less limescale building up inside.
Tea and coffee
Less limescale in the cup.
Every day
Same tap, same lever, same housing. Nothing else changes.
Standard or +
Swipe sideways to see the whole table
| Advanced or Nano | Advanced+ or Nano+ | |
|---|---|---|
| Filtration | The filtration of your filter | The same filtration |
| Limescale stage | — | Yes, developed specifically for limescale |
| Fits | Puure® 3.0 Tap System | Puure® 3.0 Tap System |
| When to replace | Depends on how many people live at home. See how often | |
Where water is hard
Hardness depends on local geology: limestone regions have harder water and more limescale.
Much of the South East and East of England, including London, has hard to very hard water: limescale in kettles and appliances is the visible sign.
It can change from one postcode to the next. See your own report
Questions
Does a filter remove calcium and magnesium?
The Nano filter lets calcium and magnesium pass through: no demineralisation, no reverse osmosis. The + option was developed for hard water, to reduce limescale in the kettle, tea and coffee.
Is a water softener the same thing?
No. A softener is installed on the whole house supply. The limescale option sits in your Tap System filter, for the water you drink and cook with.
Can I add the limescale option to my subscription?
Yes. Write to customercare@puurefilters.com with your order number and we switch your next filters to Advanced+ or Nano+. Managing your subscription
Is there a limescale option for the shower?
No. The limescale option is for the Tap System filters: Advanced+ and Nano+.
Will it descale my kettle?
It does not remove limescale already there. Descale the kettle once, then the filter helps it stay clean longer.
Still need help?
Most answers are in our Help Center: fitting, filters, subscription, delivery and returns. Otherwise, write to customercare@puurefilters.com with your order number. We'll find the best solution with you.
