Published 15 May 2026 · Prime Water Singapore
ORP, or Oxidation-Reduction Potential, is a measurement of water's tendency to either oxidize (take electrons from) or reduce (donate electrons to) substances it contacts. Measured in millivolts (mV), a positive ORP indicates oxidizing water — like tap water at +200 to +400 mV — while a negative ORP indicates reducing water. Ionized alkaline water typically has an ORP between −300 and −825 mV, with lower (more negative) values indicating greater reducing potential. ORP is directly measurable with an ORP meter and is considered a verification of electrolysis performance in water ionizers.
Starting From First Principles: What Is Oxidation?
Oxidation is one of the most fundamental chemical processes. In simple terms, oxidation means losing electrons. Reduction means gaining electrons. Every time a substance oxidises, another substance is reduced — they happen together, which is why the process is sometimes called a "redox reaction."
You see oxidation every day: iron rusts (iron atoms lose electrons to oxygen), a cut apple turns brown (phenolic compounds oxidise on contact with air), and your skin ages (cellular components oxidise over time). In biological systems, oxidative damage from reactive oxygen species is associated with cellular ageing and various health conditions.
ORP measures the tendency of a substance to cause or prevent oxidation — expressed in millivolts (mV).
Positive ORP vs Negative ORP: The Key Numbers
| Water Type | Typical ORP (mV) | Tendency |
|---|---|---|
| Singapore tap water | +200 to +400 mV | Oxidizing |
| Standard filtered water | +100 to +300 mV | Slightly oxidizing |
| Freshly squeezed orange juice | −50 to −200 mV | Mildly reducing |
| Ionized water (9-plate, Level 3) | −610 mV | Strongly reducing |
| Ionized water (13-plate, Level 4) | −825 mV | Strongly reducing |
When you look at these numbers, you start to see why people interested in antioxidant intake pay attention to ORP. The difference between tap water and ionized water is not marginal — a swing from +300 mV to −600 mV is a 900 mV difference in electrochemical potential.
How ORP Is Related to Molecular Hydrogen
When water is ionized through electrolysis, two things happen simultaneously that contribute to the negative ORP:
- Molecular hydrogen (H₂) is dissolved into the water. H₂ acts as an electron donor — a reducing agent — which directly contributes to the negative ORP value.
- Other reducing compounds are produced at the electrolysis cathode, contributing additional reducing capacity.
This is why ORP and H₂ concentration are related but not identical measurements. You can have a negative ORP water with relatively low H₂ (if other reducing species are present), or you can have H₂-rich water with a strongly negative ORP. In a quality ionizer, both measurements should be present simultaneously.
The Limitation of ORP as a Health Metric
Here is where intellectual honesty is important. ORP is an excellent verification tool for confirming that an ionizer is performing electrolysis correctly. However, directly extrapolating ORP measurements into specific health outcomes inside the body is more complicated.
When negatively charged water enters your stomach, it contacts gastric acid (which has a very positive ORP). The reducing capacity of the water is partially neutralised in this environment. How much of the reducing capacity ultimately reaches your cells — and what it does there — is a more complex question that the research is still working to answer.
We present ORP as a performance verification metric for your ionizer — not as a direct health claim. What we can say with certainty is: a negative ORP confirms that your ionizer is producing electrolysed, reduced water with measurable antioxidant potential. What tap water or filtered water cannot do.
How to Measure ORP Yourself
ORP is measured with an ORP meter — a handheld device with a probe you dip into water. Quality ORP meters cost SGD $100–$500 and are available from laboratory supply stores or online. The reading is instantaneous.
At every Prime Water home demo, we measure ORP live using a calibrated meter so you see the actual reading from your ionizer — not a spec sheet number.
Frequently Asked Questions
What does ORP mean in water?
ORP stands for Oxidation-Reduction Potential. It is measured in millivolts (mV) and indicates whether water tends to oxidize (positive ORP) or reduce (negative ORP) the substances it contacts. Tap water typically has a positive ORP of +200 to +400 mV. Ionized alkaline water has a negative ORP, typically between −300 and −825 mV depending on the ionizer model and setting.
Is lower (more negative) ORP always better?
A more negative ORP indicates greater reducing (antioxidant) potential in the water. However, the practical benefit depends on how much of that reducing capacity survives the journey through your digestive system and reaches your cells. The scientific literature is still exploring this question. What is clear is that a negative ORP confirms proper electrolysis and the presence of electron-donating compounds in the water.
What is the ORP of Singapore tap water?
Singapore tap water typically has an ORP of +200 to +400 mV, reflecting its oxidizing nature after chlorination and distribution. This is consistent with tap water in most cities globally.
Can I measure ORP at home?
Yes. ORP meters are readily available and affordable. They provide an instantaneous reading when a probe is dipped into water. Prime Water measures ORP live at every home demo using a calibrated meter so you can verify the reading yourself.
Is negative ORP water the same as antioxidant water?
Negative ORP water has measurable reducing (antioxidant) potential in the electrochemical sense. Whether this translates into equivalent antioxidant activity inside the body to the same degree as food-based antioxidants is a question the research is still investigating. What is established is that negatively charged water contains electron-donating compounds, primarily dissolved molecular hydrogen, that are not present in tap or filtered water.
See your ORP reading live — at your home.
We bring a calibrated ORP meter and measure your tap water vs ionized water side by side. You see the difference in real numbers.
Book a Free Home Demo →发布于 2026年5月15日 · Prime Water 新加坡
从基本原理说起：什么是氧化？
氧化是最基本的化学过程之一。简单来说，氧化意味着失去电子；还原意味着获得电子。每当一种物质被氧化，另一种物质就会被还原——两者同时发生，因此该过程有时被称为"氧化还原反应"。
您每天都能看到氧化过程：铁生锈（铁原子将电子失给氧气）、切开的苹果变褐色（酚类化合物与空气接触后被氧化）、皮肤随年龄衰老（细胞成分随时间氧化）。在生物系统中，活性氧引发的氧化损伤与细胞老化及各类健康问题有关。
ORP衡量的是物质引起或阻止氧化的倾向——以毫伏（mV）为单位表示。
正ORP与负ORP的关键数据
| 水的类型 | 典型ORP（mV） | 趋势 |
|---|---|---|
| 新加坡自来水 | +200至+400 mV | 氧化性 |
| 标准过滤水 | +100至+300 mV | 轻度氧化性 |
| 鲜榨橙汁 | −50至−200 mV | 温和还原性 |
| 离子水（9板，第3档） | −610 mV | 强还原性 |
| 离子水（13板，第4档） | −825 mV | 强还原性 |
看到这些数据，您就能理解为什么关注抗氧化摄入的人会关注ORP。自来水与离子水之间的差距并非微不足道——从+300 mV到−600 mV是900 mV的电化学势差。
ORP与分子氢的关系
当水通过电解被离子化时，两个过程同时发生，共同形成负ORP：
- 分子氢（H₂）溶入水中。H₂作为电子供体——还原剂——直接促成负ORP值。
- 电解阴极产生其他还原性化合物，提供额外的还原能力。
这就是为什么ORP和H₂浓度相关但并不相同。您可以有负ORP但H₂含量较低的水（如果存在其他还原性物质），也可以有强负ORP的富氢水。在优质离子机中，两项测量结果应同时存在。
ORP作为健康指标的局限性
这里需要坦诚说明。ORP是确认离子机是否正常进行电解的优秀验证工具。然而，将ORP测量值直接外推为体内特定健康结果，则更为复杂。
当负电位水进入胃部，会接触胃酸（具有很高的正ORP）。水的还原能力在这一环境中会部分被中和。有多少还原能力最终到达您的细胞——以及在那里发挥什么作用——是研究人员仍在探讨的更复杂问题。
我们将ORP作为离子机的性能验证指标提供——而非直接的健康声明。可以确定的是：负ORP证实您的离子机正在生产电解还原水，具有可测量的抗氧化潜力。这是自来水或过滤水无法做到的。
如何自行测量ORP
ORP用ORP仪测量——一种手持设备，将探头浸入水中即可读数。优质ORP仪售价约SGD $100至$500，可在实验室供应商处或网上购得。读数是即时的。
在每次Prime Water上门体验时，我们均使用经校准的仪器现场测量ORP，让您看到来自离子机的实际读数——而非规格表上的数字。
常见问题
ORP在水中代表什么意思？
ORP代表氧化还原电位，以毫伏（mV）为单位，表示水倾向于氧化（正ORP）还是还原（负ORP）与其接触的物质。新加坡自来水ORP通常为+200至+400 mV。碱性离子水ORP为负值，通常在−300至−825 mV之间。
ORP越低（越负）就越好吗？
ORP越负，水的还原（抗氧化）潜力越大。然而，实际效益取决于这种还原能力通过消化系统后能保留多少。可以确定的是，负ORP证实了正确的电解过程以及水中电子供体化合物的存在。
新加坡自来水的ORP是多少？
新加坡自来水的ORP通常为+200至+400 mV，反映其经氯化处理和配送后的氧化性。这与全球大多数城市的自来水一致。
我能在家测量ORP吗？
可以。ORP仪易于获取，将探头浸入水中即可即时读数。Prime Water在每次上门体验时均使用经校准的仪器现场测量ORP，供您自行验证。
负ORP水与抗氧化水是同一回事吗？
负ORP水在电化学意义上具有可测量的还原（抗氧化）潜力。这种效果在体内是否与食物来源的抗氧化剂具有同等活性，仍是研究人员正在探讨的问题。可以确定的是，带负电位的水含有电子供体化合物（主要是溶解分子氢），这是自来水或过滤水所不具备的。