Soils with slower percolation rates need larger drain fields. True 75% Not sure 25% Get Free Quotes Today! Question: Soils with slower percolation rates need larger drain fields. Top Answer (75% of 4 votes): True. Answer: Not sure Explanation: There are alternative systems available to reduce the amount of drain field needed. Bayshore Construction 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? Clay soils typically have slow percolation rates.Top answer: True