My Brewtus IV-R arrived yesterday. After reading the information that came with it I am unable to find any specs on the intake water line pressure or flow rate. I have a very effective RO filter system with softened water. The treated water faucet on our sink only puts out about 1/2 gallon per minute. I need to determine if this is going to be adequate for the rotary pump.

Can you help me out?

Thanks.

More than likely, you need an accumulator - see here - https://www.freshwatersystems.com/ . 1/2 gallon per minute will cause your pump to cavitate.

2.50 bar or 35 psi is a reasonable pressure at the machine inlet during brew conditions. Why not post a link or a pic of your RO system as espresso tastes best when RO water is mixed with tap water and 100% RO water is not compatible with the water level control system in your steam boiler.