Remember the science class when the teacher told us that Acids turn the Litmus paper red. And, bases turn the litmus paper blue.

All of you must have wondered how this magic happens!

As far as I recall, it was my first ever experiment in the Science Lab. I still remember how much curious I was to see that how cola, lemon and Colgate change the colour of litmus paper.

Well, that was our first experience with the concept of pH.

Let us now understand what does the right pH level mean for drinking water.

What Does PH Mean?

Basically, pH indicates whether the solution is acidic or alkaline.

If a solution has a pH value less than 7, it is acidic. For example, lemon juice, orange juice, cola etc.

And, a solution having pH value above 7, is alkaline. For example, detergent water, blackboard chalk, toothpaste, etc.

Pure water has a pH value of 7 and is called ‘neutral’ because it is neither acidic nor basic.

How Do We Measure PH?

The two most common methods to measure pH of water are:

1. Using A PH Paper

Do not confuse pH paper with a litmus paper.

A litmus paper only tells you whether the solution is acidic or basic. But a pH paper shows you the actual value of the solution.

Just dip the pH test strip into the solution and compare it with the colour chart that came with the paper.

2. Using A PH Meter

A pH meter reads from 0 to 14. Simply, dip the pH meter into the solution and wait until the measurement becomes steady.

Nowadays, water quality tester ‘pens’ are available which give an accurate pH reading.

What PH Value Is Safe For Drinking Water?

We all know that pure water has a pH value of 7.

It is tasteless, colourless and odourless. We need to add some minerals and salts to make it drinkable.

So, the addition of minerals and salts to the water changes its pH value.

According to BIS (Bureau of Indian Standards), water in the range of 6.5 to 8.5 is acceptable.

Type of Water

pH Value

Tap Water

Around 7.5 (varies)

RO Water

Between 5 and 7

Bottled Water

6.5 to 7.5 (between 8 and 9 if water is labelled ‘alkaline’)


Around 8

Acid Rain

5 to 5.5

The normal pH value for surface water is 6.5-8.5 and for groundwater is 6-8.5. However, Groundwater Pollution decreases the pH level of water.

Frequently Asked Questions

1. Does pH Affect the Taste of Water?

Acidic Water

Acidic water (with pH less than 6.5) has a bitter or metallic taste. Acids can corrode metals.

The acidic water may carry Heavy Metal, impurities from the pipelines on its way towards your home.

To treat such kind of water, you need an RO Water Purifier to neutralise acids.

Alkaline Water

Water with pH value greater than 8.5 is bitter. It also smells unpleasant.

Such kind of water is extremely hard in nature. It is highly contaminated with metals like copper, iron, zinc, etc.

Public Water Supplies use Chlorine for removing heavy metal impurities from the water.

The more the hardness, the more Chlorine is used! In turn, it affects the health.

You can use a water softener if the TDS Level of Water is not very high. You can also use an RO Water Purifier if you don’t know the TDS level.

2. What Does an Unsafe pH Mean?

pH of water varies across the globe depending upon the weather, human activities and natural processes.

Fluorides present in drinking water also disturbs its normal pH level.

A safe pH range of water is between 6.5 and 8.5.

Water with very low and high pH means that there is Chemical or Heavy metal pollution in it.

3. Is the pH of Drinking Water a Health Concern?

Generally, alkaline water is not considered unsafe for health.

According to some evidence, alkaline water helps to reduce the symptoms of acid reflux.

Acidic water which has a pH less than 6.5 is more likely to be polluted with chemicals.

4. What are the Effects of Alkaline Water?

Though alkaline water is considered safe, it may have some side effects:

An excess of alkalinity in the body can cause gastro issues and skin irritation.

Too much alkali in the body may affect the body’s normal pH.

It can cause ‘alkalosis.’ This metabolic condition causes symptoms like vomiting, nausea, liver problems, etc.

Alkaline water is very hard in nature. It leaves salt deposits on the vessels and other the household fittings.

It forms scales on electronic gadgets and decreases their efficiency.

5. What are the Effects of Acidic Water?

Acidic water can damage the pipes and metals.

Acidic water also contains heavy metals impurities which can destroy your health. The metal impurities get deposited inside the body and cause harm.

It leaves blue-green stains on the sinks and other drains.

It also leaves stains on clothing.

6. Do We Need to Alter the pH of Drinking Water?

Our body is capable of maintaining the pH on its own. For example, our stomach secretes HCL (Hydrochloric Acid) to protect the body from bacteria.

Our body can digest acidic substances. For example, we drink coffee which has a pH value of 5.5.

Also, pH is not the only factor which determines the quality of drinking water.

However, altering the pH value changes the taste of water.

As discussed above, sometimes the water may contain heavy metal impurities in large amount. In that case, altering the pH value of water becomes important.

7. What Is the Treatment for Water pH?

If the pH value of your drinking water falls outside the safe range, it’s high time to act.

If you suspect problems like bad taste, bad smell, strange texture, pH, etc., you can install a water purifier system in your kitchen.