A clogged drain and a failing sewer line can start out looking almost identical: a slow flush, a little gurgle, a smell you catch once and then forget.

You crank the handle closed, walk away, and a minute later you hear it: the slow tap of water hitting the basin. The handle is off. The water is off. And the faucet is still leaking. If that has you wondering whether something is broken deep inside the fixture, you are reading the situation correctly. A faucet that drips after you shut it off almost always has one worn internal part that no longer forms a tight seal against the water pressure sitting behind it.

Three weeks in the house, and the billing period printed on the invoice is longer than that.

You crouch down at the same spot on the garage floor you photographed yesterday morning, running a thumb across the concrete to check it's really dry this time.

When one sink drains slowly, you probably have a local clog in that fixture's trap. When the toilet, the tub, and the floor drain all misbehave at the same time, something different is happening. The problem is no longer at any single fixture. It has moved to the pipe they all share.

The valve boxes at the edge of the yard usually look identical to each other, four green lids set flush in the gravel.

You turn on the faucet expecting clear water and instead get a rusty brown stream, a yellow tint, or a glass that looks cloudy. It is unsettling, and the first question is always the same: Is this dangerous, and what is causing it? The good news is that the water itself is doing you a favor. The color is a signal, and each shade points to a different source. Once you learn to read that signal and combine it with a couple of simple checks, you can usually narrow the problem down to a single pipe, appliance, or fixture without guessing.

The showerhead that used to blast now dribbles through half its holes. There is a white crust ringing the faucet, spots on the glasses no matter how you dry them, and a water heater that has started to rumble like there are rocks in it. None of that is a coincidence. It is the same culprit, and it is dissolved in nearly every drop of water entering the house.

You crouch at the curb, wedge a flathead screwdriver under the lip of the meter box lid, and pry it free.

Two pages sit on the kitchen counter. One is a folded work order with a hand-drawn rectangle and an X marked near the hallway.

A sewer line buried a few feet down is one of the wettest, warmest things in your yard, and a tree spends its whole life hunting for exactly that. Roots do not break into a sealed pipe by force. They follow a trail of moisture leaking from a hairline crack or a tired joint, reach the source, and slip a thread-thin tip through the gap. From there, it is all growth. Once you see where roots find their opening, the clogs and slow drains in a tree-lined yard stop looking mysterious.

Two years after the repair, a folder comes off the shelf. There is a rectangle of newer paint on the hallway ceiling.

That rumble or knock when the water heater kicks on can sound alarming, but the cause is usually simple and well understood. It's the sound of water fighting its way through a layer of mineral sediment at the bottom of the tank. The noise itself is mostly harmless, but it's a useful warning: it means sediment has built up, and that buildup is quietly costing you efficiency and tank life. Here's what's happening and what to do about it.

You open the water bill, and it's twice what it usually is, so you walk through the house looking for the puddle that explains it — and there isn't one. That's the frustrating part about a high water bill: the biggest wasters are almost always invisible, running silently inside a toilet, under the slab, or out in the irrigation system. Here's how to track it down without guessing.

The repair is finished. A short length of copper lies on a drop cloth with a split in it you can see through; the water is back on, and the new fitting is holding.

When a single faucet trickles, the problem is usually that fixture. But when the pressure is weak everywhere — the shower, the kitchen sink, the washing machine all underwhelming — the cause is somewhere upstream, affecting the water before it ever reaches your fixtures. Tracking it down is a matter of working from the supply inward.

That endless hiss or trickle from a toilet long after you've flushed isn't just annoying — it's water running straight down the drain, around the clock. The good news is that a running toilet is one of the most common and most fixable plumbing problems, and the cause is almost always a worn part inside the tank.

Run a dry hand down a water heater's shell, from the top rim to the base, and you can find every inch dry, while a wet ring keeps spreading on the floor beside it.

Grease and sand traps serve as silent guardians beneath many commercial kitchens and service areas.

The yard looks exactly like it did last month. The grass along the fence line might be a shade greener than the rest, but nothing is standing in a puddle, nothing sounds like running water when you step outside at night, and there is no damp patch working its way across the patio.