Maintenance of pervious concrete is necessary when the percolation rates of the pervious concrete dip below 100 gallons per hour. Acceptable percolation rates are usually in the 210-500 gallons per hour range. The easiest procedures for maintenance and cleaning are, step one: to pressure wash the surface. This will loosen the debris that is logged into the pervious concrete voids. Next, step 2: is to use a vacuum that will suck up the loosened debris. Test results on pervious concrete that has been severly clogged can be brought back to percolation rates of 90%, or about 190-450 inches per hour.