An infiltration test will help you determine if the soil on your property is suitable for certain types of stormwater management measures, such as a dry well or rain garden. An infiltration test measures how quickly water can soak in and flow through the soil. You can perform your own infiltration test at home, with a few simple materials.
3-lb. empty coffee can
Can opener or butcher’s knife
Hand sledge and wood board or block
Stopwatch or timer
Pen and paper
Step 1. Clean and cut the can:
Clean out the inside of the coffee can and cut the bottom off with a can opener or butcher’s knife.
Step 2. Make inch marks on can:
Hold a ruler against the inside of the can. Mark the can three inches from the bottom, then place another mark 4 inches from the bottom.
Step 3. Drive the can into soil:
Clear the sampling area of surface residue, etc. If the site is covered with vegetation, trim it as close to the soil surface as possible. Make sure the site is dry.
Place the can in the section of soil. Lay a wooden board over the top of the can. Strike the board with the hammer until the can is driven into the ground to the three-inch mark.
If the soil contains rock fragments and the can cannot be inserted to the appropriate depth, gently push the can into the soil until it hits a rock fragment.
Step 4. Add water:
Pour clean water into the can, up to the four-inch mark. As soon as the water has been poured, begin the stopwatch.
Step 5. Record the time:
Record the amount of time (in minutes) it takes for the 1 inch of water to infiltrate the soil. Stop timing when the surface is just glistening.
If the soil surface is uneven inside the ring, count the time until half of the surface is exposed and just glistening.
Step 6. Repeat Infiltration Test:
Using the same can, perform Steps 4 and 5 with a second inch of water. Record the number of minutes elapsed for the second infiltration measurement.
Repeat the test (Steps 4 and 5) a few more times. All of the tests should be conducted consecutively.
If you conduct multiple tests and they produce the same result, this result is most likely an accurate estimate of the saturated infiltration rate.
Step 7. Determine infiltration rate:
If the soil infiltrates the water under 1 hour, your soil is ready for a dry well, rain garden or any of the other structural stormwater projects recommended here.
If it takes over an hour for one inch of water to infiltrate the soil, then your site is not appropriate for stormwater management, as it will not allow for natural infiltration.
For More Information
Soil Infiltration Test Video
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