If you’ve ever noticed that your hair and scalp feel dry, brittle, or itchy after washing, you may be dealing with hard water. While hard water is safe, its high mineral content can affect both your hair and scalp over time. For many people, this means dryness, itchiness, and issues that can sometimes mimic or aggravate existing scalp concerns.
In this guide, we’ll break down how hard water can affect the scalp, how to recognise the signs, and what you can do to manage or minimise its impact.
What is hard water?
Hard water is water that contains elevated levels of dissolved minerals, particularly calcium and magnesium. Around 60% of the UK is affected. These minerals occur naturally as water filters through rocks and soil, meaning hardness levels can vary significantly depending on where you live.
Over time, these minerals can accumulate on the scalp, contributing to dryness and visible flaking. Hard water may also lead to a build-up of dead keratin cells on the scalp, which can further increase irritation, a dry scalp, and flakiness.
How do you know if you have hard water?
Signs of hard water include:
- White mineral deposits on taps or showerheads
- Soap that doesn’t lather easily
- A film or residue left on skin or hair after washing
- Glassware that looks cloudy after washing
Many regions in the UK have hard water due to limestone-rich geology. Rainwater filters through chalk and limestone, absorbing higher levels of calcium and magnesium. This is why areas such as the South East, East Anglia, and parts of the Midlands often experience particularly hard water.
In contrast, regions with granite or slate bedrock – such as Scotland, Wales, and the South West – tend to have softer water. Because of this geological variation, two households only a few miles apart can have noticeably different water hardness, which may influence how their hair and scalp feel after washing.
How does hard water affect the scalp?
Some scalps can be particularly sensitive to changes in mineral composition. Here are some of the ways you could be affected:
1. Hard water can disrupt the scalp’s moisture balance
The minerals in hard water can react with natural oils on the scalp, leaving behind a residue that may make the scalp feel dry, tight, and itchy. This dryness can be uncomfortable and may even worsen existing scalp issues.
2. Mineral build-up can irritate the scalp
Regular washing in hard water can cause mineral deposits to accumulate on both the hair and scalp. This residue may contribute to flakiness or irritation, especially in people prone to dryness or sensitivity.
3. Hard water may exacerbate visible flaking
While hard water doesn’t cause dandruff, psoriasis, or seborrhoeic dermatitis, the dryness and irritation may make flaking more noticeable in individuals already dealing with these conditions.
Hard water vs scalp conditions: understanding the difference
It’s important to distinguish between dryness caused by hard water and scalp disorders. Hard water does not cause scalp disorders, but the symptoms of the following conditions may feel more noticeable:
- Psoriasis
- Seborrhoeic dermatitis
- Eczema of the scalp
- Dandruff
- Itchiness or scaling associated with these conditions
Persistent symptoms may indicate an underlying scalp condition that requires appropriate treatment. You may also need to seek medical advice from a doctor or pharmacist to advise on the most appropriate treatment option for you.
How to reduce the effects of hard water on the scalp
1. Moisturise the scalp when needed
Scalp-friendly oils or serums designed for sensitive skin may help rebalance moisture levels. If you have a scalp disorder, check with a doctor or pharmacist first to make sure the treatment won’t cause further irritation.
2. Install a shower filter
Some filters remove mineral deposits, making the water gentler on your skin and hair. They’re easy to install – you can simply attach the showerhead filter to your existing pipe setup.
3. Rinse thoroughly after washing
Ensuring all shampoo and conditioner is fully rinsed away can help reduce residue on the scalp.
4. Use a medicated shampoo when managing scalp conditions
If dryness, flakiness, itchiness, or scaling is caused by a scalp condition such as psoriasis, seborrhoeic dermatitis, eczema, or dandruff, you may benefit from using a medicated shampoo licensed for these conditions, such as Polytar Scalp Shampoo. Find out more below.
How Polytar Scalp Shampoo fits in
While hard water itself does not cause a scalp disorder, the dryness or irritation it contributes to can sometimes make existing conditions feel worse. If your symptoms are linked to an underlying scalp condition rather than simply mineral residue from hard water, a medicated shampoo such as Polytar may help.
About Polytar Scalp Shampoo
Polytar Scalp Shampoo is a licensed medicated shampoo containing coal tar solution 4% w/w. It is indicated for the treatment of:
- Psoriasis of the scalp
- Seborrhoeic dermatitis
- Eczema affecting the scalp
- Itchiness and scaling associated with psoriasis, seborrhoeic dermatitis, and eczema
- Dandruff
- Itchy, oily scalp
As a coal tar shampoo, Polytar helps slow down the excessive skin cell production linked with many scalp disorders and helps reduce scaling and itching.
Always ensure:
- You use the shampoo only as directed
- You read the label before use
- You consult a doctor or pharmacist if symptoms persist or get worse
Final thoughts
Hard water doesn’t directly cause scalp disorders, but it can contribute to dryness, itchiness, and irritation – especially if you are already prone to scalp issues. Understanding the signs of mineral build-up and taking steps to minimise its effects can help keep your scalp comfortable.
