Montana State University Land Resources and Environmental Sciences Water Quality HomePage

Chapter 1-What is Water Quality?

Water quality can be easily influenced by what we do on the land.

Overview: To appreciate the importance of water quality, we must understand what water quality is. This lesson presents an overview and general principles of water quality.

Purpose: The purpose of these activities is to introduce students to water quality and cause them to think about its importance.

Ideas Taught:

  • What we do on the land can easily affect water quality, although the effects may not be immediately apparent.
  • Water quality is a relative term.

Materials Needed:

  • Red or green food coloring
  • Small plastic cup
  • One teaspoon of water
  • Orange, grapefruit, or lemon (grapefruit works best)
  • Paper towels
  • Disposal syringe or hypodermic needle

Procedure: The lesson has five parts, each illustrating one or more of these principles.

  1. ___ Before class, add one to two drops of food coloring to one teaspoon of water in plastic cup. Swirl to mix.
  2. ___ Draw the colored water up into the syringe. Invert the syringe and expel any air.
  3. ___ Insert the needle into the grapefruit, almost to the center. Very slowly, push the plunger in, forcing the colored water mixture into the grapefruit. Avoid pushing the plunger too fast, or the food coloring will squirt out the needle hole. Wait about a minute
    4. .
  4. ___ Remove the syringe. Wipe the grapefruit clean of any food coloring.
  5. ___ If you want the class to participate, repeat the process with several grapefruit. The longer the grapefruit set, the more dramatic the effect will be.

Introduce the Subject of Water Quality:

We cannot know what the quality of water is simply by looking at it. Sometimes we do not know the effects our actions have on water quality for a long time. We may influence water quality adversely, without knowing it. We rely on the on surface water (lakes, streams, ponds, reservoirs, the ocean) and on ground water (wells) for water. Ground water is commonly acceptable for public water supplies because it is generally not contaminated by either sediment or bacteria and generally does not need to be treated before it is safe to drink.
  1. ___ Ask the class if they have questions. Invite them to join you in a break. Casually mention that the grapefruit is like the earth in several ways. It is round, has a protective skin (like the soil surface) and has liquid under the surface.
  2. ___ Pass the grapefruit and some paper towels to a student, ask him or her to peel the grapefruit and share it with the class.
  3. ___ Continue talking about water quality and the importance of water in our lives.
  4. ___ Tell the students On the average, we each use between 120 and 200 gallons of water a day
  5. ___ Explain that the quality of water depends on the intended use. Have the students talk about all the different uses of water and the quality of that water.

Lesson Learned:

What we see is not always what is really there. Ground water is usually safe from contamination, but we cannot always see the effects of our actions on ground water. Sometimes it takes a long time for the effects of our actions to show up, particularly in water quality. We need to understand water quality process and be careful about what we do.

The lesson above was adapted from "What is Water Quality? A Resource Guide for 4-H Leaders and Teachers," 80 pages of activities and experiments related to water quality. ($5.00) Order from the Montana 4-H Program at Montana State University-Bozeman. Phone 406-994-3501.

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Questions/Comments: waterquality@montana.edu