Test the master cylinder. Open the master cylinder reservoir cap and remove the brake fluid from the cylinder using a syringe or baster. If the fluid is in good condition, save it in a clean container for reuse. Carefully remove the brake lines from the bottom of the master cylinder and securely plug the line connections on the master cylinder with suitable caps or plugs. Refill the reservoir to the appropriate level, replace the reservoir cap, start the car and apply the brakes. If the brake pedal now feels firm and high, the master cylinder is functioning properly.
You may have a buildup in the pipe leading to the faucet. If the piping is galvanized piping, it's most likely accumulated debris from age and sediment. You can remove or unscrew the riser from the basement with a pipe wrench. Back up the fitting in the basement so the fitting or pipe attached does not break. With a bucket and another person, turn the water on and see what the pressure is from the pipe that you just removed. If it’s good, replace the piece that you just removed. If it’s not good, a re-pipe of the entire home will be needed.