pressure is not. When you turn off your main valve, the water inside the line right next to the valve will rapidly reduce until it reaches an equilibrium to maintain height of water inside your house. If you live in a ranch house, your water level is probably about 10 ft. Then water pressure is 4.33 psi. If you live in a two floor house, your water level is probably about 20 ft. Then water pressure is 8.66 psi. Your city water is mostly about 60 psi. So, 4.33 or 8.66 is very small compared to 60 psi. Engineers who designed your valve knew what they were doing (LOL). So, don't worry about it.
Best regards,
Alex
