A:Answer Hi Curious, Thank you for your question. You should only require an additional pump if your water pressure from the water tank is insufficient. Greenworks pressure washers requires at least 35 P.S.I of constant pressurized water flow. This would be standard when the unit is connected to a household waterline. Please be advised anything less than 35 P.S.I of consistent pressurized waterflow will cause extra stress on the pump and motor, resulting in wear and premature failure. We hoped this helped!
