Filtering Yucky Water—Facilitator’s Guide
In this activity youth will be designing and constructing a filter to remove smell and color
from a water sample. You will need to make the water sample and prepare the different
media that are used. It’s not a big deal, but might be something to do several hours ahead
of time, perhaps the day before.
https://www.epa.gov/dwstandardsregulations/secondary-drinking-water-standardsguidance-nuisance-chemicals
http://www.extension.umn.edu/environment/water/treatment-systems-for-householdwater-supplies-iron-and-manganese-removal/
Making the Yucky Water
Prepare yucky water at least one day in advance.
You will need about a gallon of prepared water; you will use vinegar to create the smell and
dissolved iron vitamin tablets to create the yellow color.
Materials:
1 gallon jug (empty water bottle)
Iron Vitamin Tablets
Small cup for rinsing tablets
Measuring spoons
Apple Cider Vinegar
In a cup, rinse two iron vitamin tablets (65—100 mg) to remove the coating. All vitamins
have a coating to prevent oxidation of the iron in the tablet. To do this, put water in the
cup, swish around and dump out, repeat until coating is removed. It does not take long, a
few minutes. Once the coating is removed, crush the pill for faster dissolving and put in
gallon water container and add water part way up. Then the smell comes, use apple
vinegar (nice yellow color also); add in 7/8 teaspoons (two tablespoons) of vinegar. Add
the vinegar just before using as it may inhibit the oxidation of the iron particles. Shake and
add more water to fill the container. Let sit for a few hours or overnight. The longer the
dissolved sits, the more it oxidizes and the more yellow the water will become.
Filtering the Yucky Water
If children have a fish tank at home, they may be familiar with the materials used in this
project, as they are used to filter and purify the water in the tanks.
Materials:
Activated Charcoal (granular)
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Zeolite
Sand
Coffee filters
Rubber bands
Eye dropper
Kitchen Strainers (medium sized for Facilitator, small for youth)
Measuring cups
Paper/plastic plates
8 oz plastic cups for pouring and collecting water
Soft plastic water bottles (0.5 liters)
Preparation ahead of time
The children will be making their own filters using a water bottle that the bottom has been
cut off (tape around the cut rim if it is sharp). They will take the top off and put a coffee
filter around it, held in place by a rubber band. Then, when the bottle is inverted, filtering
media put in, and yucky water poured through, the media will not come out of the bottle.
The filtering media needs to be rinsed ahead of time to remove dust and particulates, hence
the need for a large kitchen strainer (small ones for the teams). Put each media (activated
charcoal and zeolite) in the strainer (rinse the charcoal in a container first, then strain) and
let water run over it until it runs clean. Put on a plate to dry for the children to use. With
the sand, put in a container and fill with water, stir; floating particulates and some dirt will
appear; rinse and repeat until rinse water is clear. Put on plate to dry.
The design criteria the children will be testing for are: clarity on a scale of 1—4 to the
original and test samples (1 being the best, 4 being the worst); smell on a scale of 1—4
(need to create test samples for comparison) and cost.
Creating clarity and smell test samples (this is very similar to the procedure done in actual
water testing). Take four 0.5 liter water. Put tape on the bottles and label 4, 3, 2, 1. Add a
cup or two of the original yucky to the bottle labeled number 4. Take ¼ cup of original
yucky water and add it to the next bottle (labeled 3), fill with clean tap water, cover and
shake. Next take ¾ cup from bottle number 3 and add to an empty bottle number 2, fill
with clean tap water, cap and shake. Last take ¼ cup from bottle number two and add it to
an empty bottle number 1, fill with clean tap water, cap and shake. Put the cover on for
storage. These are you test samples for clarity and smell. The least clear and the most
smelly is 4 and the clearest and least smelly is 1. There will also be a picture in the project
online of the samples for clarity.
Design Time
In this design challenge children will be given materials for a cost and they need to design
the most effective filter. The effectiveness will is given by the formula
Effectiveness = Smell x Clarity x Cost
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The three filtering media (sand, zeolite, activated charcoal) work on different principles;
the sand strains; the zeolite works on an ion exchange (we’ll explain in the design activity)
and the activated charcoal works by adsorption. The activated charcoal is effective for
removing color and smell; zeolite works less well for metals and ammonia; and sand filters
particles/color and may have a slight effect on smell.
The ordering of the media in the water filter matters; the activated charcoal will tend to
float, so it needs to be sandwiched in by the sand and/or zeolite to be most effective. The
teams can select the amount of material they want to use, up to the maximum for each one.
They can use lesser amounts and then should calculate the proportional cost.
Cost (maximum amounts and cost for same)
½ cup Zeolite—$1.00
½ cup Activated Charcoal—$2.00
2 cups Sand—$0.75
Design Challenge Implementation
We are assuming two person teams; therefore you will need 7 or 8 bottles with their
bottom cut off and taped to prevent any possible cuts. Teams are given two measuring
cups, three paper/plastic plates for the material, a coffee filter and a rubber band. They
will decide on how much material they want to use and come to you for this. After layering
their filter material they should add a cup of clean water to the filter and let it drain out
into a cup. Then they can dump the water that drains out and their filter is then ready for
testing. You will also dispense the Yucky water. As they are doing the activity, they will
see and smell the test samples. You can have them self-assess the clarity and smell, or
several youth can be designated the testers for these.
They may want to redesign their filters; it is easy to do so. Basically they empty the
material from the bottle onto a plate, separate and wash with water (hence small strainers
for zeolite and activated charcoal); the sand is too fine for the strainer and will need to go
in a cup, have water mixed around and pour out. If there is no sink, then there can be
buckets of water for this.
There will be perhaps time for one redesign. Then the children complete the design
activity and clean up.
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