Do Perc Tests Expire? In some cases 50% Not sure 50% Get Free Quotes Today! Question: Do Perc Tests Expire? Top Answer (50% of 4 votes): Not sure. Each jurisdiction has different rules in regards to this issue. In most cases, the results of a soil percolation test are usually valid for three to five years. 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