Porosity/Permeability Lab - Honors
_____ / 20 Lab Grade
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Background: Just how solid is “solid ground?” The material beneath our feet is rarely solid. Soil is made up of particles
of rock and the spaces between these particles. The amount of space between soil particles is called porosity. You can
estimate the porosity of a soil by measuring the amount of water it can hold. Underground, water percolates down
through soil and flows from higher elevations (such as a hill) to lower elevations. The ease with which water moves
through a soil or rock type is called permeability. You can estimate the permeability of soil by timing how quickly water
can flow through it.
Objective: I will predict and test the porosity and permeability of four sediments by following the steps of this lab.
Predict: Below, list the three sediments (soil, sand, gravel) in order from most to least permeability and porosity.
Porosity: 1. ____________________
Permeability: 1. ____________________
2. ____________________
2. ____________________
3. ____________________
3. ____________________
Procedure: Carefully follow the steps. Be sure to fill in the data tables with accurate information and units!
Part 1 – Porosity
1. Get two small beakers. Fill one with 40 ml of gravel, and one with 40 ml of water.
2. Slowly pour the water into the gravel. Stop pouring once the gravel looks saturated. Record the volume of
water (you poured in, not left in the beaker) on your data table. Repeat this for sand, and soil.
3. Calculate the porosity of the material: (pore space / volume ) x 100 = Porosity
4. Put the wet soil, sand, and gravel in the buckets in the back. Wash AND dry the beakers and put them back.
Part 2 – Permeability
1. Get two beakers. Fill one beaker up with 40 ml of water and the other with 40 ml of gravel.
2. Get a plastic funnel and three pieces of filter paper (coffee filters)
3. Fold the filter paper in half and place it in the funnel, pour the 40 ml of gravel into the funnel. Hold the funnel in
the now empty beaker.
4. Get a stop watch (or use your phone) – SLOWLY begin to pour the water into the sediment, as soon as you start
to pour the water into the gravel start the timer. Do not stop the timer until all of the 40 ml of water has filtered
through to the beaker. Record time on data table.
5. Place wet sediment in the buckets in the back of the classroom, and throw away the used filter.
6. Repeat steps 3-5 for sand, soil, and gravel.
7. Wash, dry, and return materials.
Data Table
Material
Gravel
Sand
Soil
< --------------------------------Part 1 ------------------------------ >
Total Volume (ml)
Pore Space (ml)
Porosity (%)
< -------Part 2 ----- >
Permeability (time)
Graph your results:
 Graphs must be on graph paper
 You must use a ruler
 Be sure to have axis labeled and a PROPER title
 Attach both graphs to this page
Answer the following questions; in full sentences
1. Which material is most porous? _______________________________
2. Which material is least porous? _______________________________
3. How does sediment type affect the movement of water? (give specific examples using data).
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4. Did your results match your predictions? (give specific examples using data).
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5. If you drilled a well into these materials, which one do you think would yield the most water? (give specific examples
using data).
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