How To Assess Your Soil Drainage: A Guide to Completing An Infiltration Test

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An infiltration test is a good way to determine if your yard is suitable for a rain garden or soakaway.

  1. Dig a hole in the proposed location of your project to a depth of 50 cm.
  2. Fill the hole with water to saturate the soil.
  3. Return a couple of hours later and fill the hole with water again. This time measure the depth of the water in the hole.
  4. Wait 60 minutes and measure the depth of water again.
  5. Determine your infiltration rate with this calculation: Depth of water at beginning of hour minus Depth of water at end of hour.

For me: 17cm – 9cm = 8cm

8cm / 60 minutes = my infiltration rate.

An infiltration rate of 2cm or higher suggests your soil is well-draining and may be suitable for a rain garden or infiltration trench.