We finally called the plumber to deal with our water woes that began a few weeks ago. Mark showed up bright and early at 830 this morning and began calling me "young lady."
He stuck some sort of pressure valve on the basement sink and we quickly learned that our water pressure is actually higher than that of a fire hose. Over 150 pounds of pressure per square inch flow through our copper pipes every time we turn the spigot. Mark said he was surprised more of our fixtures hadn't been leaking or exploded by now.
Since our previous owners, famously odd contractors, built drywall around the water main to the house, Mark had to saw into the wall to fix the broken pressure valve but then he helped with a preventative measure and installed an "expansion tank" so we have lower pressure now. Around 50 pounds per square inch. It still feels like we have plenty of water, but now the faucet doesn't jump like a startled puppy when I go to rinse my hands.
Thanks to the awfully cold weather cracking our valve, we caught a potentially disastrous situation before it ruined our house. Yay for Mark!