Hard Water Link to Childhood Eczema

Peter Russell

June 03, 2016

Babies exposed to hard water may have a higher risk of developing the skin condition eczema than those who live in areas of the country with soft water, according to a UK study.

Atopic eczema is a chronic condition characterised by patches of itchy, dry, red and thickened skin.

It affects about 1 in 5 children in the UK. In 8 out of 10 cases, the condition develops before a child reaches the age of 5. Many children develop it before their first birthday.

Previous studies in the UK, Spain and Japan found associations between domestic water hardness and the risk of eczema in schoolchildren. However, the link between water hardness and eczema has not been studied in babies.

Researchers from King's College London studied 1,303 infants from across the UK and checked what type of water they were exposed to. They also checked chlorine levels in the water where the infants lived.

Hard or Soft

There is a scale of water hardness based on the amount in milligrams of calcium carbonate (CaCO3) in each litre.

In broad terms, tap water is usually softer in the north of the UK and in Devon and Cornwall, and hardest in the South East of England and East Anglia.

The infants in the study were checked for childhood eczema and their skin barrier was checked for impairment.

They found that babies growing up in hard water areas were up to 87% more likely to have childhood eczema when they were 3 months old than those in soft water areas.

They were unable to determine whether chlorine levels affected eczema development.

'Growing Evidence'

Lead researcher Dr Carsten Flohr from St John’s Institute of Dermatology at King’s College London and Guy’s and St Thomas' NHS Foundation Trust says in a statement: "Our study builds on growing evidence of a link between exposure to hard water and the risk of developing eczema in childhood.

"It’s not yet clear whether calcium carbonate has a direct detrimental effect on the skin barrier, or whether other environmental factors directly related to water hardness, such as the water’s pH, may be responsible.

"Interactions between hardness and chlorine levels, other chemical water constituents and the skin’s microflora may also play a role, and this warrants further research."

The research team are planning a new trial to test whether installing a water softener in the homes of high risk children around the time of birth may reduce the risk of eczema and whether reducing chlorine levels brings any additional benefits.

The study is published in the Journal of Allergy and Clinical Immunology.

Reducing Risk

Commenting on the findings to us, Matthew Gass of the British Association of Dermatologists says: "This study is an interesting examination of the link between hard water and eczema, which has been demonstrated in different groups in previous studies.

"As the evidence proving this association begins to stack up I hope that this will inspire new ways to help those living hard water areas reduce their risk of eczema.

"As hard water affects a large proportion of the UK, particularly in England, understanding the relationship between hard water and eczema is important."


'The Association between Domestic Water Hardness, Chlorine and Atopic Dermatitis Risk in Early Life: A Population-Based Cross-Sectional Study' Perkin et al, Journal of Allergy and Clinical Immunology.

Press release, King's College London.

Matthew Gass, British Association of Dermatologists.

'Atopic eczema', NHS Choices.