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Do Detergents Work Best in Cold or Hot Water?

Do Detergents Work Best in Cold or Hot Water?

Introduction: (Initial Observation)

The detergent industry is one of the biggest industries in the world today. This is because everyone uses detergents. Clean clothes are important to everyone, and getting clothes clean is not hard as long as the correct methods and products are used.
The basic items needed to clean clothes or anything else for that matter are water and detergents. Many people worry about getting the right brand-named detergent, however the most important part is having the right type of water when cleaning. Detergents do not work good in salt water or waters with lots of dissolved minerals.

How about the temperature? Does it matter if we use cold water or hot water while washing dishes or clothes?

In this project you will test to see if the temperature is a factor in the ability of detergents to remove stains.

This project guide contains information that you need in order to start your project. If you have any questions or need more support about this project, click on the “Ask Question” button on the top of this page to send me a message.

If you are new in doing science project, click on “How to Start” in the main page. There you will find helpful links that describe different types of science projects, scientific method, variables, hypothesis, graph, abstract and all other general basics that you need to know.

Project advisor

Information Gathering:

Find out about what you want to investigate. Read books, magazines or ask professionals who might know in order to learn about the effect or area of study. Keep track of where you got your information from. Summary of collected information can be like this:

Hot Water

  • Removes dirt from heavily soiled items
  • Kills more germs than cold water
  • Fades the dyes in some colored clothes
  • Tends to cause wrinkling in some modern fabrics such as permanent press

Warm Water

  • Usually gets lightly soiled clothes clean
  • Does not kill germs unless a disinfectant is added
  • Is safe for most colored clothes

Cold Water

  • Requires a cold-water detergent to get clothes clean.
  • Requires more detergent than warm water to get clothes clean
  • Does not kill germs unless a disinfectant is added
  • Mostly used for the washing of delicate fabrics

Question/ Purpose:

What do you want to find out? Write a statement that describes what you want to do. Use your observations and questions to write the statement.

Do detergents clean better in cold, warm or hot water? Many factors play a role in how well detergents work such as the amount of water and the type of water (hard or soft). However, we will be concentrating on the temperature of the water in this experiment.

Identify Variables:

When you think you know what variables may be involved, think about ways to change one at a time. If you change more than one at a time, you will not know what variable is causing your observation. Sometimes variables are linked and work together to cause something. At first, try to choose variables that you think act independently of each other.

The independent variable (also known as manipulated variable) is the water temperature.

The dependent variable is the time it take for a stain to be removed.

Controlled variable is the room temperature.

Constants are the type of stain, dryness of stain, type of water, amount of water, type of detergent, amount of detergent, type of fabric or cloth and the experiment method.


Based on your gathered information, make an educated guess about what types of things affect the system you are working with. Identifying variables is necessary before you can make a hypothesis. This is a sample hypothesis:

Since most water soluble material dissolve best in hot water, hot water is best for washing and detergents work faster in hot water.

This is another sample hypothesis:

Since germs and bacteria cannot survive in very hot temperatures, the hot water will probably clean better than the cold water. However, the hot water may also destroy the colors of the clothing so the warm water will probably clean the best out of all three temperatures.

Experiment Design:

Design an experiment to test each hypothesis. Make a step-by-step list of what you will do to answer each question. This list is called an experimental procedure. For an experiment to give answers you can trust, it must have a “control.” A control is an additional experimental trial or run. It is a separate experiment, done exactly like the others. The only difference is that no experimental variables are changed. A control is a neutral “reference point” for comparison that allows you to see what changing a variable does by comparing it to not changing anything. Dependable controls are sometimes very hard to develop. They can be the hardest part of a project. Without a control you cannot be sure that changing the variable causes your observations. A series of experiments that includes a control is called a “controlled experiment.”

Sample Experiment:

To test our hypothesis, we will stain three pieces of cloth. Then, we will attempt to remove the stain with detergents and the three temperatures of water.


1.) Stain the three pieces of cloth with the ketchup.

2.) Label the three bowls with Hot, Warm, and Cold

3.) Take the three bowls and pour the water with different temperatures into appropriate bowls.

4.) Put 4 spoons of the detergent into each bowl and mix the water and detergent together.

5.) One by one, dip the scrubbing brush into the mixtures and scrub each stained piece of cloth. Note how long and how much pressure it takes to remove the stain from the cloth with each mixture.

6.) Record the results.

Record your results in a table like this:

Water Temperature Time to clean (Minutes)

Use the above results table to draw a bar graph. Make 3 vertical bars. Name them Cod, Warm and Hot. The height of each bar must show the cleaning time. Use one inch for each minute it took. So if it takes 3 minutes for the warm water to clean the stain, warm bar will be 3 inches tall.

Materials and Equipment:

1.) 3 pieces of cloth

2.) 3 small bowls

3.) Masking tape and pen to label bowls

4.) Liquid or powdered detergent of your choice

5.) Bottle of Ketchup

6.) Hot Water (preferably between 150-175 °F)

7.) Warm Water (preferably between 75-100 °F)

8.) Cold Water (preferably between 40-60 °F)

9.) A scrubbing brush

10.) a spoon

Results of Experiment (Observation):

Experiments are often done in series. A series of experiments can be done by changing one variable a different amount each time. A series of experiments is made up of separate experimental “runs.” During each run you make a measurement of how much the variable affected the system under study. For each run, a different amount of change in the variable is used. This produces a different amount of response in the system. You measure this response, or record data, in a table for this purpose. This is considered “raw data” since it has not been processed or interpreted yet. When raw data gets processed mathematically, for example, it becomes results.


Not needed.

Summary of Results:

Summarize what happened. This can be in the form of a table of processed numerical data, or graphs. It could also be a written statement of what occurred during experiments.

It is from calculations using recorded data that tables and graphs are made. Studying tables and graphs, we can see trends that tell us how different variables cause our observations. Based on these trends, we can draw conclusions about the system under study. These conclusions help us confirm or deny our original hypothesis. Often, mathematical equations can be made from graphs. These equations allow us to predict how a change will affect the system without the need to do additional experiments. Advanced levels of experimental science rely heavily on graphical and mathematical analysis of data. At this level, science becomes even more interesting and powerful.


Using the trends in your experimental data and your experimental observations, try to answer your original questions. Is your hypothesis correct? Now is the time to pull together what happened, and assess the experiments you did.

A sample conclusion is:

Warmer water does work better, however, the temperature of the water used for cleaning mostly depends on the material of the item you are cleaning. However, laundry detergents are formulated to clean best at temperatures above 60°F.

Related Questions & Answers:

What you have learned may allow you to answer other questions. Many questions are related. Several new questions may have occurred to you while doing experiments. You may now be able to understand or verify things that you discovered when gathering information for the project. Questions lead to more questions, which lead to additional hypothesis that need to be tested.

Possible Errors:

If you did not observe anything different than what happened with your control, the variable you changed may not affect the system you are investigating. If you did not observe a consistent, reproducible trend in your series of experimental runs there may be experimental errors affecting your results. The first thing to check is how you are making your measurements. Is the measurement method questionable or unreliable? Maybe you are reading a scale incorrectly, or maybe the measuring instrument is working erratically.

If you determine that experimental errors are influencing your results, carefully rethink the design of your experiments. Review each step of the procedure to find sources of potential errors. If possible, have a scientist review the procedure with you. Sometimes the designer of an experiment can miss the obvious.


Visit your school or local library to find books about detergents. Review them add use them as your references.