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How to Tell if Tap Water is Acidic

by Peter Lombardi

Quality Specialist, Consultant

> 4 min read

Filling up a glass with clean drinking water from kitchen faucet

Taking care of overly acidic water in your house is vital since it can corrode metal pipes and damage home appliances like water heaters. Also, very acidic water is unsafe to drink because it leaches metals from plumbing, contaminating your household water supply. 

Water acidity is measured on a pH scale. The number 7 on the scale is considered neutral, and anything below 7 is acidic. Testing your tap water acidity can be achieved in a few steps. This can help you decide what action you need to take to improve your home’s water quality.


ph level

What is Acidic Water

The pH scale indicates how acidic or alkaline a substance is. Our blood naturally has a pH of about 7.3, being slightly on the scale’s alkaline side. When it comes to drinking water from the tap, you want to ensure your water is neutral or slightly alkaline. The United States Environmental Protection Agency recommends keeping public water between a pH of 6 and 8.

Why Does Water Become Acidic

Essentially, acidic water comes from acidic rain. When water evaporates and condenses in the sky forming clouds, it mixes with carbon dioxide and numerous other gases. When water and carbon dioxide combine, they create carbonic acid, creating slightly acidic rain.

When the earth absorbs rain, the soil’s quality affects water by either making it more acidic or bringing it back to neutral. If the water is absorbed through alkaline-rich soil, that balances the pH. But if there’s a lack of minerals in the soil, the pH of that water can become even more acidic.

What’s Wrong With Acidic Water

There are several problems with acidic water. Water with a pH under 6.5 is more likely to be contaminated, and it also corrodes the inside of your pipes and damages any home appliances that run on hot water. Hot water makes acidic water more harmful because it makes the water more corrosive. 

How to Test the Acidity of Your Tap Water

ph scale

There are two main ways for how to tell if tap water is acidic. One uses a pH meter, and the other is using pH paper. You can also perform a litmus paper test, but this only tells you if the substance is alkaline or acidic. It doesn’t give you a specific degree of acidity or alkalinity. 

Using a pH meter

A pH meter should be calibrated before using. A simple way to do this is by testing the meter with a liquid that you already know the pH level of. You could do this with bottled water that has a specific pH. Once you know the meter is working correctly, try it on a glass of water from your tap. 

Simply place the probe in the glass or water container and wait. You should allow enough time for the meter to do its work. Anything between a pH of 6 and 8 means the water is relatively pure in your home. 

Using pH papers

Prepare a small container with tap water—dip part of the test strip in the container for a few seconds. The strip of paper should change color. You can use the color chart on the pH strip package to check your water’s pH. 

Get the Water in Your Home Tested

Once you have learned how to test if tap water is acidic, consider doing a more extensive check on your water quality. This allows you to know what kind of metals, bacteria, and chemicals are in your home’s water. 

An effective way is to use a water test kit and send it to a water filter company for testing. Many companies offer this service, and it’s a great way of getting a more accurate idea of your water quality. 

The test can tell you how many and what types of chemicals, metals or bacteria the water contains. Most tests check for up to 20 or more metals. 

How to Make Water More Neutral

There are different ways to fix acidic water in your home’s pipes. These methods apply different substances to the water in your home’s pipes, such as calcium or magnesium. Applying these substances affects the water and brings up the pH. 


One of the most common ways is to run calcite through the pipes. Water naturally dissolves calcite, and this raises the pH of the water. Calcite can move pH one point up the scale, so it has some limitations, and it can’t fix extremely acidic conditions. 

Magnesium Oxide 

For very acidic water, another substance can be used in addition to the calcite. This is magnesium oxide, also known as Corosex or Flomag. Use a mixture that is about 80-90% calcite and 10-20% magnesium oxide. Combining these two substances neutralizes the acidity of water and raises the water’s pH a total of 1.5 points. You don’t want to use a lot of it because too much magnesium in water acts as a laxative. 

Soda Ash Or Caustic Soda

When water is very acidic, below a pH of 5 and close to 4, a more potent chemical is needed. You should ask for the help of an expert and install a peristaltic pump that injects water with a dissolved mixture of soda ash before it enters your house. This prevents the corrosion of your pipes and home appliances, although it’s a system that requires maintenance and the help of an expert to install. To make it easy for you, just setup a water filter to make sure what you're drinking is safe and avoid these unwanted diseases.

Enjoy Fresh and Clean Water in Your Home

Checking the pH level of your tap water is easy and quick. You can easily buy a pH meter or some pH papers online and use them to check the water’s pH level. You might want to do a more comprehensive test on your water quality and buy a water testing kit. The company will tell you exactly how to use the kit, but essentially, you send them some water samples, and they provide an extensive report on the metals, bacteria, or chemicals found. BPA chemicals are also a threat to your family which is harmful to your body. 

Once you have all this information, consider bringing your water’s pH back to normal if it’s too acidic. If your water is polluted with chemicals or heavy metals, investing in a high-quality water filter can provide your household with clean, pure water.  

Peter Lombardi

About the Author

Peter is a Los Angeles based water quality specialist, and works as a surveyor for businesses and communities looking to be informed and active about the quality of their water. He shares his expertise with 64 oz. to ensure everything is accurate, and to prevent the spread of misinformation about water contaminants.