Is purified drinking water (PDW) suitable for mixing with infant milk formula?

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Last updated: November 28, 2025View editorial policy

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Purified Drinking Water for Infant Formula Preparation

Purified drinking water is safe and appropriate for mixing infant formula, provided it meets drinking water standards and the formula is prepared according to manufacturer instructions. 1

Water Safety for Formula Preparation

The primary concern with water for infant formula is not the type of purification, but rather:

  • Fluoride content: Purified drinking water typically has low or no fluoride, which actually reduces the risk of dental fluorosis in infants who consume formula as their primary nutrition source 1
  • Microbiological safety: Any water used for formula preparation should be safe from pathogens 1
  • Mineral content: While some bottled waters may have high mineral content, most purified drinking water available in supermarkets is chemically suitable for infant formula preparation 2

Key Preparation Guidelines

The critical factor is proper formula preparation technique, not the water source:

  • Formula should be prepared according to manufacturer's specific instructions, as standard dilution varies by product 3
  • Each manipulation during formula preparation introduces potential for bacterial contamination 3
  • Proper hygiene during preparation is essential 3

Fluoride Considerations

Using purified water with low fluoride content may actually be beneficial:

  • Infants consuming formula prepared with fluoridated water (0.7-1.2 ppm) can ingest 0.21-0.54 mg fluoride per day, with some infants receiving as much as 1.73 mg per day 1
  • This can contribute to mild dental fluorosis, affecting 10-12% of children in optimally fluoridated areas 1
  • Purified drinking water typically contains minimal fluoride, reducing this risk 1

Common Misconceptions

Healthcare professionals often incorrectly advise against bottled or purified water:

  • A review of bottled waters readily available in supermarkets found they are chemically suitable for infant formula preparation 2
  • The NHS advice against bottled water has created confusion without providing appropriate alternatives 2
  • This misinformation can lead parents to use truly unsafe water sources or feeding methods 2

What Water to Avoid

The only waters that should be avoided are:

  • Unpasteurized or contaminated water sources 1
  • Water with excessive mineral content (though this is rare in commercial purified drinking water) 2
  • Water from unknown or untested sources 1

Bottom Line

Purified drinking water is not only acceptable but may be preferable to fluoridated tap water for formula preparation, as it reduces fluoride exposure while maintaining safety standards. The focus should be on proper formula preparation technique and hygiene rather than the specific type of purified water used. 1, 2, 3

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Is bottled water really unsafe for making up infant formula?

Community practitioner : the journal of the Community Practitioners' & Health Visitors' Association, 2010

Research

What's in the Bottle? A Review of Infant Formulas.

Nutrition in clinical practice : official publication of the American Society for Parenteral and Enteral Nutrition, 2016

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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