• StoneStream

Hard Water Areas In The UK

Updated: Mar 27

You’ve probably heard the words ‘hard water’ and ‘soft water’ many times before and weren’t sure exactly what they meant. After all, they’re both liquid and if you jump into a swimming pool, the water bruises your legs just the same. So, how can water be hard or soft?

Believe it or not, the answer to the question refers to the concentration of dissolved minerals in the local water.



So, what is hard water?

Let’s think this through using the rain cycle as an example.


Water falls to earth from clouds as rain. This water has no dissolved minerals so scientists class it as ‘soft’. It lands on the ground and percolates through the soil and underlying rocks. If the rocks are permeable like limestone or chalk, the water will collect mineral salts on its journey. Magnesium and calcium compounds are the most common, but other minerals dissolve too. If the water ends up with high mineral content then we call it ‘hard water’.

The water collects in aquifers in the ground, where water suppliers extract it and pipe it to our homes. As a general rule of thumb, you could say that hard water comes from an underground porous rock aquifer while soft water comes from surface reservoirs. Furthermore, the amount of water hardness you have to put up with depends on the geology of the area where your domestic water comes from.

Which areas of the UK have hard water?

Most of the south and east of England has hard water, while most of Wales, Devon and Cornwall and Northwest England have soft water.


As you can see on the attached map of the UK and Ireland, the hard water areas don’t follow national, county or postcode boundaries. They are entirely dependent on the underlying chalk and limestone geology of the area.

Do I live in a hard water area?

The map shows only approximately whether an area has hard water or not. Don’t forget, it’s where the water comes from that counts, not where you live. If you really want to know, visit your local water company’s website where you will find an online tool that will tell you whether your domestic water is hard or soft. Just enter your postcode in the search box. You can find out who your local water supplier is by looking up your postcode at the Water.org.uk website.

Map of hard water areas in the UK

Is hard water bad for you?

You might think that all these dissolved minerals in your domestic water might cause problems with your digestive system. Maybe it’s a cause of kidney stones? Well, as far as medical science is aware, hard water doesn’t cause problems with either of these. In fact, the dissolved salts actually contribute a small amount of the necessary minerals our bodies need. Hard water does, however, cause problems with skin and hair. But, more about that in the next section.

What negative effects will hard water have?

So far it seems that the minerals dissolved in hard water cause no internal health problems. So are there any other, problems in hard water areas?

The answer to this one is yes. They’re mainly to do with household appliance efficiency, bathing, and beauty products:

  1. You’ll find that hard water causes problems with limescale build-up. This occurs within household appliances. Solids settle out of solution and coat the inside of water heaters, pipes and nozzles. You’ll also find limescale clogging up showerheads and covering heating elements within kettles and central heating water tanks. In fact, even a limescale coating as thin as 1.5mm on a water heating element can reduce its efficiency by 12% causing higher utility bills. That’s something you could certainly do without!

  2. You’ll need more detergent in the washing machine if you want your clothes to be clean and soft.

  3. Hard water can damage hair dyes and cause them to fade more quickly than expected.

  4. You use more hand and face soap in hard water areas to produce a satisfactory lather. Soap also produces scum easier which builds up on your skin and blocks pores.

  5. You’ll find that skin moisturisers are less effective on your skin.

  6. Some of the minerals in hard water, such as calcium and iron, form ‘free radicals’. These attack your skin and damage healthy skin cells. Hard water minerals also prevent the natural oils in your skin from doing what they’re meant to do.

What can I do to fix the problems?

Now for the science bit!


First, let’s talk about preventing water hardness. You can use an ‘ion exchange’ water softener. Now, this isn’t as high tech as it sounds, but it needs a bit of chemistry knowledge to understand what’s going on.

The water softener consists of small round balls, about 1 to 2mm in diameter, made from a special resin. They’re packed into a tube (known as a column) and primed with sodium ions from water softening salt.


Hard water percolates through the column and exchanges its calcium and magnesium ions for sodium ions. The result is that the hard water ions attach themselves to the ion exchange resin and the sodium ions leave the exchanger with the outgoing water. Simple!


Hard water softening process

You might have looked inside your dishwasher and noticed a container used to hold what is known as dishwasher salt. Yes, you guessed it. It’s salt designed for the ion exchange column within the dishwasher. It prevents limescale from building up and allows you to use less detergent. After each use, a salty brine washes over the ion exchange resin to flush away the calcium ions and replace them with sodium ready for the next wash.


Now, a way to treat hard water for use in washing clothes. Have you ever heard of ‘washing soda’? Its chemical name is sodium carbonate and it has the ability to soften water by removing the calcium ions from solution. Sodium carbonate dissolves in water and allows its ‘carbonate’ parts to link up with the dissolved calcium. The resulting compound, calcium carbonate, isn’t soluble so it settles out as a precipitate.

Commercial water softeners

Luckily, the manufacturers of ion exchange water softeners make it really easy for us. They either come already built into the appliance and all you do is add salt, or you can buy cartridges containing the resin which plugs into a holder within the water stream. After a certain time, all you do is change the cartridge for a new one. Either way works, you just make your choice.

Keep your water soft

We hope you found this information useful and you now know a bit about water hardness. As we said earlier in the article, you need to know a little bit of chemistry but it's not that difficult.


All you have to remember is that areas with chalk or limestone rocks supply hard water. There are manufacturers who supply water fittings designed to deal with hard water both as drinking water and washing water. Keep your eyes peeled for these products and check out our hard water filtering shower heads and accessories on our website at Stone-Stream.com. They will certainly make life much more comfortable for you and your family.


It’s as simple as that. Thanks for reading.


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