Remove loose material, such as stones, dirt, and other debris, from the entrance surface. Applying a degreaser will loosen stains on concrete, allowing you to wash them under pressure. To effectively clean concrete, use a pressure washer with a nominal pressure of at least 3000 psi and a flow rate of at least 4 gallons per minute (gpm). While higher pressures may be required to remove strong contaminants, such as paint and heavy tire skid marks, most pressure washing contractors agree that 3000 psi is sufficient for almost all cleaning jobs.
Pressure washing of the inlet starts at the highest end. Run the washing machine in the same direction as the water flow. Hold the spray rod pointing directly at the surface of the inlet and pull the trigger. Pressure washers increase garden hose water pressure to more than 1,000 pounds per square inch.
Once you've connected the garden hose from the faucet to the pressure washer, don't be too anxious to turn it on. You can rent or buy a pressure washer and clean the concrete yourself, or more, a contractor who offers pressure washing services and has commercial-grade equipment. There's no doubt that electric pressure washers at 1300 to 2300 psi can wash a concrete inlet, but they'll take longer. Running out of gas when washing or rinsing the inlet is inconvenient, but there is also a risk that the concrete will dry out during the washing process.
The motor inside the pressure washer powers the water pump, which pressurizes the water to ensure that it comes out stronger than found with a garden hose. To improve the cleaning power of your pressure washer, use a homemade pressure washing solution or a commercial cleaner for outstanding results.