Shower’s a sad little drizzle. The pot takes five minutes to fill. Sound familiar? Low water pressure is annoying way before it’s ever an emergency, and honestly, the cause could be anything: a crusty aerator, a valve that’s giving up, something in between. So you narrow it down. Here’s roughly how we’d do it if we were standing in your kitchen. Is the low water pressure in one fixture or the whole house? First question,…