Nanobubbles and Detergent Reduction

ByNanoBubbleGuide Editorial

Washing & Cleaning

Published June 2025 · 7 min read · NanoBubble Guide

Commercial nanobubble washing devices are commonly marketed with detergent-reduction claims ranging from 30% to full elimination. This article reviews the peer-reviewed literature on the subject, describes the underlying mechanism, and sets out the conditions under which reported reductions occur.

The evidence supports a real detergent-reduction effect. Reported figures vary substantially, mainly because they depend on the gas used and on test conditions that are not always disclosed. The sections below cover what has been measured, and what determines the size of the effect.

The mechanism

Water has surface tension, a cohesive force at the liquid-air interface caused by hydrogen bonding between water molecules. Surface tension is what causes water to bead on a surface rather than spread into a thin film.

Detergents reduce this surface tension. Surfactant molecules position themselves at the water-fabric interface, disrupting hydrogen bonds and allowing water to penetrate fibre pores and lift soil particles. This is why plain water is largely ineffective on greasy soils.

Nanobubbles are gas-filled cavities measuring 50-200 nm. They accumulate at solid-liquid interfaces because of their negatively charged surface (zeta potential typically -20 to -40 mV), which is attracted to the generally positive charge of soiled surfaces. This accumulation disrupts the same hydrogen-bond network responsible for surface tension. In effect, nanobubbles act as a partial surfactant substitute: not through chemical reaction, but through a physical reduction of the cohesive forces at the water surface, which improves wetting, spreading, and penetration.

A 2006 study in the Journal of Surfactants and Detergents measured washing rates of cotton cloth in nanobubble water compared with ion-exchanged water. Nanobubble water produced measurably higher washing rates, and the combination of nanobubbles with anionic surfactant outperformed the surfactant alone at the same concentration.¹ This surfactant-nanobubble synergy accounts for most of the detergent reduction observed in practice.

Reported reduction ranges by gas type

The commonly cited 30-50% range comes primarily from ozone-infused nanobubble systems, not from air or oxygen nanobubbles. This distinction is rarely stated in product marketing.

System Gas used Reduction range Notes
Air nanobubbles only Air ~10-20% Surface tension reduction without added oxidation. Modest but consistent effect.
Oxygen nanobubbles O2 ~15-25% Mild oxidative contribution aids soil breakdown.
Ozone nanobubbles O3 30-50% Oxidant degrades organic soils directly. Highest reported reduction; ozone generation adds cost and complexity.

Patent filings from washing machine manufacturers, including several by Japanese appliance brands dating to the 1990s, document ozone bubble systems achieving 30-50% detergent reduction alongside a 4-5% improvement in cleaning degree.² This range represents the upper bound achievable under controlled laboratory conditions.

Laboratory results use standardised soiled fabrics at controlled temperatures with defined bubble concentrations. Domestic washing introduces variables — mixed fabric types, hard water, varied soil loads — that tend to lower measured performance relative to lab benchmarks. A 40% reduction under controlled conditions may translate to roughly 20-25% under typical household use.

Factors affecting reported results

Several variables account for most of the difference between published research and reported real-world outcomes:

  • Gas type. The 30-50% figures apply to ozone systems specifically. Applying them to air-only or oxygen-only generators does not reflect the underlying data.
  • Water hardness. Nanobubble stability decreases as ionic strength increases, since zeta potential drops with higher mineral content in the water. This shortens bubble lifetime and reduces the surface-tension effect. Water hardness is rarely specified alongside performance claims.
  • Bubble concentration. The number of nanobubbles per millilitre determines the magnitude of the effect. Consumer devices typically report concentrations in the millions per millilitre, versus billions per millilitre for industrial generators used in published studies.
  • Temperature. Nanobubbles dissolve faster at higher temperatures. Most studies showing significant detergent reduction were conducted at 30-40°C; the effect diminishes substantially at 60°C.

Established findings

The following points are supported by multiple independent studies:

  1. Surface tension reduction from nanobubble-enriched water is measurable and reproducible, improving wetting and penetration into porous materials including textile fibres.
  2. Detergent reduction is achievable under controlled conditions with adequate bubble concentration. For consumer air/oxygen systems, the supported range is roughly 10-25%.
  3. Ozone nanobubbles produce a larger, separately verified effect (30-50%), attributable to the added oxidative chemistry.

Bubble concentration as a reporting gap

Bubble concentration — the number of nanobubbles per millilitre — is the main variable determining the size of the surface-tension effect, and it is rarely disclosed in consumer product documentation.

Industrial UFB generators capable of producing billions of bubbles per millilitre are costly and energy-intensive, and are generally sized for commercial or agricultural use. Consumer devices produce substantially fewer bubbles. This gap between research-scale concentrations and consumer-device output is the largest identifiable source of difference between published results and reported household outcomes.

Summary

The literature supports a real detergent-reduction effect from nanobubble washing, based on an established physical mechanism rather than an unverified claim. The frequently cited 30-50% figure applies specifically to ozone-infused systems under laboratory conditions. For air or oxygen nanobubble systems at typical consumer concentrations, a supported range is 10-25%, with results depending on water hardness, wash temperature, and soil type. A claim exceeding this range, without disclosure of gas type, bubble concentration, and test conditions, is not supported by the current evidence.

Questions for evaluating a manufacturer’s claim

  1. What gas does the device use — air, oxygen, or ozone?
  2. What bubble concentration (bubbles/mL) does it produce at operating conditions?
  3. What water hardness range was used in performance testing?
  4. At what wash temperature was the detergent reduction measured?
  5. Is the reduction figure from an independent study or internal testing?

A claim that cannot be supported with answers to these questions should be treated as unverified.

References

  1. Karasawa M. et al. (2006). Effect of Mixed Nanobubble and Microbubble Liquids on the Washing Rate of Cloth in an Alternating Flow. Journal of Surfactants and Detergents. DOI: 10.1007/s11743-012-1348-x
  2. US Patent 6,507,965 — Washing machine with functional water generator. Ozone bubble system achieving 30-50% detergent reduction with +4-5% cleaning efficiency improvement.
  3. Levitsky I., Tavor D., Gitis V. (2022). Micro and nanobubbles in water and wastewater treatment: A state-of-the-art review. Journal of Water Process Engineering, 47, 102688.
  4. English N.J. (2024). The Quest for Industrially and Environmentally Efficient Nanobubble Engineering. Applied Sciences, 14(17), 7636. DOI: 10.3390/app14177636
  5. ISO 20480-1:2017 — Fine bubble technology — General principles for usage and measurement of fine bubbles.

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