Clay soils typically have slow percolation rates. True 100% Get Free Quotes Today! Question: Clay soils typically have slow percolation rates. Top Answer (100% of 1 votes): True. Get Free Quotes Today! Find Local Pros Free Percolation Test Cost Estimates Related Questions How Much Does a Perc Test Cost? How long does it take to get the results of a perc test?Top answer: Less than 48 hours How Long Does a Perc Test Typically Take?Top answer: One full day (8 hours) What is a soil's percolation rate? What is perc testing?