You may have heard the term ‘pH values of water’ used when talking about water quality. But what does it really mean?

Here, we have a detailed and complete explanation of what pH values of water mean and what you need to understand. It will help you determine whether or not the water you use at home has any factors that may adversely affect you.

In simple terms, pH measures how acidic or basic your water is. pH stands for the power of hydrogen. So what pH measures are the relative amount of free hydrogen and hydroxyl ions in your water. It is measured on a scale that ranges from 0 to 14. This scale can be divided into three categories.

Table of Contents

Three Categories of pH Value of Water

1. Acidic Water

Acidic water is any water with a pH value lower than 7, with 0 being the most acidic. Acidic water is mainly soft and corrosive. Strong acids, such as hydrochloric acids (HCl), have a pH of 0.

Acidic water can cause damage to metal pipings and tend to have a metallic or sour taste. They can also cause a lot of health damage. Not just this, but they can stain your sinks and laundry.

2. Alkaline Water

Alkaline, also known as basic water, is any water with a pH of 8 or more. On this scale, 14 represents the most alkaline such as sodium hydroxide (NaOH). Basic Water is synonymous with hard water.

While the health risks from this are minimal, its main problem is scaling. It can add a bitter taste to your drinking water and cause scale deposits on your dishes, showers, and drains. It also reduces the effectiveness of soap and detergent.

3. Pure or Neutral Water

Pure Water is Water that has a pH of 7. This is also considered neutral as it is neither acidic nor basic. However, the ideal human drinking water can be between 6-8.5.

Why is pH Value Important?

The pH value of any substance is affected by the chemicals present in water. Similarly, it can also determine the solubility of water and the number of nutrients available in it for aquatic life. A change in pH value can thus be an indicator of pollution or any sudden change that you should be aware of.

Similarly, atmospheric gases, as well as temperature, can affect the pH value of any water. Water with widely fluctuating pH values can indicate chemical or heavy metal contamination. This is why pH value can be an important indicator of the chemical changes in any water.

Different pH Levels of Typical Materials

The following table will help you better understand the pH values of the different types of water you use daily. This will also help you know about the water you drink or wash your dishes.

Source: Khan Academy
WaterpH value
Acid rain5-5.5
Normal rainfall5.6
Distilled water after reverse osmosis5-7
Tap waterApprox. 7.5
Sea Water8
Alkaline bottled Water8-9
Bottled Water8-9

Similarly, the following is a list of other substances and their pH values. These are items you use on a near-daily basis. The following table can help you get a clear understanding of the range of pH values.

SubstancepH value
Lemon juice2
Apple Juice3
Baking soda9.5
Bleaches, oven cleaner13.5
Liquid drain cleaner14

Factors That Influence the pH of the water

By now, we have understood that the pH value is vital in understanding the water you use. However, this value is not constant. This means that it can be affected by environmental and manufactured factors. Some of these are listed as follows:

1. Carbon Dioxide

Carbon dioxide is one of the most common reasons that water turns acidic. Many natural processes, such as photosynthesis, respiration, and decomposition, cause a rise in the level of carbon dioxide. It can then react with water to form carbonic acid. This can cause an imbalance in pure water. Thus, as the carbon dioxide levels rise globally, a change in the pH values can be seen in the oceans across the world over time.

2. Natural Influence

Limestone and carbonate materials can also cause fluctuations in the pH values of water. These materials react with hydrogen and hydroxyl ions, which usually cause water to neutralize. In case of additional exposure, it can cause the water to become slightly more basic.

Similarly, natural precipitation can also lower the pH of water. Pine or fir needles act similarly. They reduce the pH of the surrounding soil so that any water that runs over it experiences a reduced pH.

3. Human Influences

The changes caused by human influences are primarily related to pollution. One of the primary examples is acid rain. Acid rain refers to rain with a pH value of less than 5, caused due to the reaction of water with acidic compounds such as nitrogen oxide, sulfur oxide, and others.

The increasing carbon dioxide discussed previously also falls under human influences. Similarly, pollution like wastewater and industrial wastes can cause an imbalance in the ecosystem. This can affect nearby water sources and even the surrounding soil.

How to Test pH Values at Home?

The first thing we need to do before testing pH is to understand how pH values are reported. They are denoted in logarithmic units, which means that every number represents a change that is 10-times more than the last.

For instance: Water with a pH of three is ten times more acidic than water having a pH of four. We don’t need complicated machinery to determine how acidic or basic our water is. We can conduct this test ourselves with something called the Litmus Test.

1. The Litmus Test

You may have done this test in your science class. It is a simple test that can let you know whether the water you are using is acidic or basic. Litmus is a mixture of organic compounds made from lichen. It is an excellent acid-base indicator.

It turns red if the water is too acidic and blue if it is too basic. It remains neutral if the pH is at 7. You can find these litmus papers at most pet-supply stores as they are used to check the pH value of aquariums.

2. pH meter

There are also many water-quality tester pens now available in the market. You will simply need to dip this pen into the sample you want to test. Usually, it would be best to calibrate the pen by immersing it in a liquid with a known pH, such as pure water.

The calibration will give a very accurate reading of the pH value of your water. As long as the sample has a pH between 6.5 to 8.5, the sample should be safe for your usage.


We must now have a much better understanding of what pH values represent. They are simply a measure of how acidic, basic or neutral your water sample is and can be affected by many artificial and environmental factors. Since they are so easy to influence, it is always handy to know how to measure these values.

(Last Updated on June 11, 2022 by Sadrish Dabadi)

Nina Howell is a Rewenable Energy researcher and consultant based out of Houston, Texas Area. She earned her Master's Degree in Energy and Earth Resources from Austin Jackson School of Geosciences in 2010, and a Bachelor's Degree in Environmental Science from State University of New York College of Environmental Science and Forestry in 2008. Nina has been working in the energy sector since 2011. She worked as an Energy Supply Analyst from 2011 to 2017 in Bounce Energy and then as a Research and Energy Consultant at GE Renewable Energy from March 2017 to February 2020 . Nina is a mom of 2 beautiful children who are joy to her life. She strongly believes in eco-friendly living and is vocal about renewable energy, environmental issues, water crisis, and sustainable living.