Carpet Cleaning pH Scale: Understanding Acidic VS Alkaline Cleaning

Understanding the pH of your carpet cleaning solution is key because it determines whether it can remove dirt, dust, and stains without removing the carpet dye or degrading its quality.

A carpet cleaning solution's pH is measured from 0 to 14. A pH of 0 to 6 is acidic, 7 is neutral, and 8 to 14 is alkaline.

Use an alkaline carpet cleaner for acidic soils and stains like battery acid, furniture polish, and chocolate. Use an acidic carpet cleaner for alkaline stains such as tannins (from coffee and tea), sweat, mineral deposits, alcohol, grass, and mustard. A neutral pH cleaner is good for light soiling.

In this article, you'll learn about the different pH levels in carpet cleaning solutions and which ones to use for different stains. Don't fret; there isn't too much biology here!

What Is the pH (Potential Hydrogen) Level of a Cleaning Solution?

The pH scale helps to measure the concentration of hydrogen ions in any solution. pH refers to the alkalinity or acidity of a cleaning solution. When you expose something to an alkaline or acidic solution, the ions cause the reaction.

The pH is measured on a scale of 0 to 14, with 14 being the most alkaline, 7 being the most acidic, and 7 being neutral.

Every number on the pH scale is 10 times the previous; for example, a cleaning solution with a pH of 2 is 10 times more acidic than a solution with 3 and 100 times more acidic than pH 4.

What pH Level Should Carpet Be Cleaned At?

When determining what pH level is ideal for carpet cleaning, you must consider several things: Stain, carpet fiber, and residue.

The Type of Stain

Dirt, stains, dust, and everything that sticks to carpets and makes them dirty also have a pH level. To determine the most appropriate cleaning solution, you must determine the pH level of whatever you want to remove from your carpet. Acidic cleaning solutions are ideal for alkaline substances and vice versa.

The Type of Fibers

Varying carpet fibers have varying levels of pH tolerance. Some carpet fibers, such as natural fibers, like cotton or wool, are more delicate than others so you should use cleaning solutions with a pH level ranging between 5 to 8.

A pH of 7 to 10 is great for synthetic fibers, like nylon, rayon, or olefin.


Carpets are slightly naturally acidic, but carpet cleaning solution residue can make them alkaline and interfere with their tolerance.

Before cleaning an old (or new) carpet, measure its pH using a pH meter to verify whether its pH has been interfered with and, based on the results, determine the best cleaning solution.

Professional Zerorez male technician cleaning a gray carpet in a living room, revealing a clean stripe in the carpet where the Zr Wand and Zr Water cleaned with an alkaline higher pH

What Is the Best pH for Carpet Cleaning?

Understanding the pH levels is vital in choosing the right cleaning solution, lest you damage your carpet fibers and colors and leave the carpet worse than it was. First, cleaning solutions/chemicals are classified into three categories:

  • Acidic
  • Neutral
  • Alkaline


Cleaners with a pH level of less than 7 are acidic, increasing their intensity as you approach zero.

Acidic solutions are great for cleaning toilet bowls and removing limescale and mineral deposits in kitchens and bathrooms because they dissolve in the acid. They also remove mold and rust stains. Acidic cleaners are great for scrubbing soap scum off commercial kitchen sinks.


Cleaners with a pH of 7 are neutral and less effective than alkaline or acidic cleaners. They cannot neutralize the effects of alkaline or acidic ions in stains, making them great for cleaning delicate fibers and removing light soil and stains from surfaces.

You can also use neutral cleaning solutions on stone, wood, laminate, tile, grout, and any other sealed surface.

To protect the color and fibers of natural carpets (cotton, jute, silk, wool, etc.), use a cleaner with a neutral pH level or slightly alkaline. Use cleaning solutions with a neutral pH when wiping office tables and desks.


Cleaners with a pH of more than 7 are considered alkaline.

Alkaline cleaning solutions have a pH of more than 7 and become more intense as you get closer to 14. Cleaning solutions with a pH of 8 or 9 have a mild alkaline quality.

Use alkaline cleaning solutions to remove oily organic residues such as proteins, fats, greases, and oils. Most soils are acidic with a pH of 2 to 5.

The Institute of Inspection, Cleaning and Restoration Certification (IICRC) recommends cleaning moderately soiled synthetic fiber (olefin, nylon, polyester) carpets with alkaline cleaning solutions with a pH of less than or equal to 10. Many carpet manufacturer warranties will not be honored if the cleaner has a pH level higher than 10.2.

Zerorez® carpet cleaning cleans carpets with an alkalized water-based cleaning solution called Zr™ Water, that has a pH level under 10. Technically, their water isn't reactive the same way that other cleaning solutions are, as it doesn't contain soap, detergents, or harsh chemicals that leave behind chemical or soapy residues.

close up a Zerorez Zr Wand cleaning a gray carpet, showing a white stripe where its high alkaline Zr Water cleaned a stripe of the carpet clean

Will a High pH Clean Carpets Better?

Yes and no! Cleaning solutions with a high pH level (more than 9) can also damage colored carpets.

Carpets made of natural fibers such as wool, cotton, jute-backed, or sisal may result in yellowing after carpet cleaning if you use a solution with a high pH level. This is why it's necessary to clean wool with a wool-safe cleaning solution.

Always using a high pH cleaning solution, unless that solution is Zr Water, to clean carpets, leaves a sticky residue, making it easy for the carpet to trap dirt and dust and prove challenging to clean.

Due to the constant use of cleaners with a high pH level, your carpet's pH level also rises, making it impossible to release all the dirt and dust during cleaning.

Ammonia, soap, bleach, and/or alkaline cleaners dissolve fats, proteins, and oils. This makes them great for mattress cleaning because they help break down oils and fats.

If your carpet and upholstery have grease and oils, a high-pH solution would help dissolve them, but it can make the carpet fibers stiff.

To prevent the carpet fibers from becoming stiff after washing them with a high pH carpet cleaning solution, rinse them using water and a neutralizer to balance the pH.

It can also make a big difference what temperature water you use to clean carpets!

What's the Best pH Level to Leave the Carpet at the Final Cleaning Process?

The pH at which you leave your carpet is crucial in ensuring it stays clean longer and that its quality is intact. Always leave the carpet close to its natural pH, usually neutral to slightly acidic. To neutralize the alkalinity after pre-spraying your carpet and remove cleaning solution residue, rinse the carpet using a low-pH rinsing product.


Is Carpet Cleaner an Acid or Alkaline?

Carpet cleaners can be alkaline or acidic, depending on the type of soil you're cleaning. Alkaline cleaners (and pre-sprays) clean acidic soils from carpets, while acidic cleaners clean alkaline soils.

Why Should You Use Professional Carpet Cleaners?

Professional carpet cleaning companies are specially trained in understanding stains and the best ways to neutralize and remove them, making them better than store-bought products and cleaning your carpets yourself.

At Zerorez, we understand the need to consider the pH level of cleaners to ensure that carpets are clean and their quality is intact. That's why, in addition to using special tools such as the Zr™ Lifter and The Zr™ Wand, we also use the Zr™ Water!

We offer commercial and residential carpet cleaning services across the country. Call us or schedule any cleaning services at any time!

Book a Cleaning with Zerorez Today!