“Electrolyzed water” is one of the most confusing terms in sanitation, because it describes a process rather than a product. Any solution made by passing an electric current through salt water is electrolyzed water. Depending on how the cell is built and run, the result can be strongly acidic, near-neutral or strongly alkaline, and it can be a powerful oxidiser or a mild cleaner. This page sorts out the types, how they relate to hypochlorous acid, and what the research literature — much of it published under names like EW, EOW, AEW, SAEW and NEW — is actually about.
About claims on this page
EcoloxTech generators produce a hypochlorous acid solution on site. They are not EPA-registered disinfectants and we make no efficacy claims for them or for the solution they produce. The only EcoloxTech product with disinfection claims is HOCl-AS200 (EPA Reg. No. 101112-1), used according to its label. Research cited here describes published studies of hypochlorous acid and electrolysed water; it is not a claim for any product.
What electrolyzed water is
When a direct current is passed between two electrodes in a solution of sodium chloride, chloride is oxidised at the anode to chlorine, which reacts immediately with water to form hypochlorous acid and hydrochloric acid. At the cathode, water is reduced to hydrogen gas and hydroxide. What leaves the cell depends on whether those two streams are kept apart or allowed to mix — and that single design choice explains almost every difference between the types below. For the full chemistry, see how hypochlorous acid works.
The types compared
| Type | How it is made | Typical pH | Dominant chlorine species |
|---|---|---|---|
| Acidic electrolyzed water (AEW, EOW) | Anode stream from a two-compartment cell with a membrane or diaphragm | Around 2–3 | Hypochlorous acid, with dissolved chlorine at the lowest pH |
| Alkaline electrolyzed water (AlEW) | Cathode stream from the same membrane cell | Around 11–12 | Little or no available chlorine; mainly hydroxide |
| Slightly acidic electrolyzed water (SAEW) | Single-compartment cell, often from dilute hydrochloric acid or salt with acid | Around 5–6.5 | Hypochlorous acid |
| Neutral electrolyzed water (NEW) | Single-compartment cell, or anode stream adjusted towards neutral | Around 6–8 | Mostly hypochlorous acid, with more hypochlorite towards pH 8 |
The distinction that matters most is pH, because pH decides what form the chlorine takes. Below about pH 7.5, most free chlorine is hypochlorous acid; above it, most is hypochlorite ion; and at very low pH, some leaves solution as chlorine gas. A near-neutral or slightly acidic solution therefore keeps its chlorine where it is most useful — as HOCl — without the gas and corrosion issues that come with very low pH.
Electrolyzed water and hypochlorous acid
People often use the two terms interchangeably. Strictly, hypochlorous acid is the molecule; electrolyzed water is one way of making a solution that contains it. Near-neutral and slightly acidic electrolyzed water are, for practical purposes, dilute hypochlorous acid solutions with a trace of salt. Acidic electrolyzed water contains hypochlorous acid too, but at a pH low enough to change its handling and material compatibility. Alkaline electrolyzed water is a different product altogether, used mainly as a cleaning or degreasing solution in the research literature.
EcoloxTech generators use a single-compartment cell and produce one near-neutral stream at pH 5.0–6.5, so their output belongs in the slightly acidic to neutral family. See single-cell vs membrane cells for why.
A short history
Electrolysis of brine is a nineteenth-century industrial process, and chlorine chemistry has been part of water treatment for more than a century. Electrolyzed water as a sanitation product was developed extensively in Japan, where electrolyzed hypochlorous acid water was designated as a food additive in 2002, and research spread quickly through food science, agriculture and healthcare. The result is a large literature, much of it on food-contact surfaces, produce, meat and poultry, and animal housing.
What the published research examines
The research hub indexes more than 300 studies. A few representative examples, by theme:
- Reviews. Electrochemically activated solutions: evidence for antimicrobial efficacy and applications in healthcare environments; Applications of electrolyzed water in agriculture and food industries; and a review of electrolyzed water as an alternative to sodium hypochlorite for fruits and vegetables.
- Neutral electrolyzed water on surfaces. Neutral electrolyzed water for sanitising cutting boards and neutral electrolyzed water for cleaning near-patient surfaces.
- Comparing types. Acidic versus neutral electrolyzed water against avian influenza viruses and acidic and alkaline electrolyzed water against several foodborne bacteria.
- Slightly acidic electrolyzed water in food. Slightly acidic electrolyzed water on refrigerated beef.
- Stability. Stability of electrolyzed oxidizing water and stability of low-concentration electrolyzed water.
These are published studies of electrolyzed water under their own test conditions. They describe the chemistry’s behaviour in research; they are not claims for any EcoloxTech product.
Stability and storage
All electrolyzed water with available chlorine loses strength over time. Light, heat, exposure to air, agitation and organic contamination all speed the loss, and very low pH adds another route: chlorine gas escaping from solution. Stability studies in the literature consistently find that closed, opaque, cool storage slows the decline, and that open or agitated storage accelerates it. The practical rules are the same whatever the type: store closed and out of sunlight, test before use, and produce close to the point of use where possible.
Measuring electrolyzed water
| Measurement | What it tells you | How |
|---|---|---|
| Free available chlorine (ppm) | How much active chlorine is present | Test strips, test paper or photometer |
| pH | What form the chlorine is in | pH strips or meter |
| ORP (mV) | Overall oxidising strength; useful as a trend | ORP meter |
Record free chlorine and pH together. A reading of available chlorine without the pH does not tell you whether the solution is mostly hypochlorous acid or mostly hypochlorite.
Common misconceptions
- “It’s just water.” It is a dilute chlorine solution. It needs the same respect as any sanitation chemical: correct strength, correct storage, no mixing with acids or ammonia.
- “Lower pH is always stronger.” Below the near-neutral range, more chlorine is lost as gas and the solution becomes harder on metals, without a practical gain for most tasks.
- “Alkaline electrolyzed water disinfects.” Alkaline catholyte contains little or no available chlorine; in the literature it is studied mainly as a cleaning solution, often used before an acidic or neutral step.
- “All electrolyzed water is the same.” The type, pH and concentration differ widely between systems, which is why research results are only comparable when those conditions are known.
Where electrolyzed water is used
The research and industry literature covers a wide range of settings. In food processing, electrolyzed water is studied for food-contact surfaces, equipment, process water and ice, and for fresh produce, meat, poultry and seafood. In agriculture, it appears in work on animal housing, drinking-water lines, hatcheries, greenhouses and irrigation. In healthcare and dentistry, it is studied for environmental surfaces, instrument pre-cleaning and, in specially formulated products, wound care. In foodservice, hospitality and schools, the interest is mostly in replacing bought-in concentrates for routine surface work. Our applications page maps these uses by task and by industry.
Whatever the setting, the same rules govern how it is used in practice: food-contact and water uses are covered by specific authorisations, disinfection claims belong to registered products used per label, and every use needs a procedure, a strength check and a record.
Made on site or bought bottled
Electrolyzed water can be produced on site by a generator or bought ready to use. Onsite production suits steady, high-volume use: the solution is made fresh at a set strength from salt, water and power, and storage time is short. Bottled, ready-to-use products suit occasional use and tasks that require a registered label claim, such as HOCl-AS200. Many sites use both. See onsite generation explained.
Glossary of abbreviations
| Abbreviation | Meaning |
|---|---|
| EW | Electrolyzed water (general term) |
| EOW / AEW / AcEW | Electrolyzed oxidizing water / acidic electrolyzed water: the low-pH anode stream |
| SAEW | Slightly acidic electrolyzed water, around pH 5–6.5 |
| NEW | Neutral electrolyzed water, around pH 6–8 |
| AlEW / ERW | Alkaline / electrolyzed reduced water: the high-pH cathode stream |
| ECA | Electrochemically activated solution, a broader term used especially in healthcare literature |
| FAC / ACC | Free available chlorine / available chlorine concentration, in ppm or mg/L |
| ORP | Oxidation-reduction potential, in millivolts |
Frequently asked questions
Is electrolyzed water the same as hypochlorous acid?
Near-neutral and slightly acidic electrolyzed water are dilute hypochlorous acid solutions. Acidic electrolyzed water also contains HOCl but at a much lower pH. Alkaline electrolyzed water contains little available chlorine.
What is EOW?
Electrolyzed oxidizing water, a term used in research mostly for the acidic anode stream of a membrane cell.
Which type do EcoloxTech generators make?
A single near-neutral stream at pH 5.0–6.5, from a single-compartment cell.
Does electrolyzed water need an SDS?
Yes. Keep the manufacturer’s SDS for the solution and for any brine or acid inputs. See HOCl safety and SDS.
Is electrolyzed water an EPA-registered disinfectant?
Solution produced by an onsite generator is not. A registered product such as HOCl-AS200 is, and it carries the label claims.
Where can I read the studies?
In the research hub, searchable by organism and by industry.