Plumbing basics: the five things that prevent a flooded house

Plumbing is intimidating because it's hidden, involves water and pressure, and fails at inconvenient times -- but the handful of things a homeowner genuinely needs to know are simple, and they prevent the expensive emergencies rather than requiring you to fix them. You don't need to sweat copper or move drain lines. You need to know where the water shuts off, what not to send down the pipes, how to handle the two or three failures that cause most floods, and which cheap fixes are genuinely DIY. That knowledge is worth thousands, because the most expensive plumbing bill is always the one that starts with water where it shouldn't be.

One: know every shutoff

This is the single most valuable piece of plumbing knowledge, full stop. When a supply line bursts, every minute of flow is roughly another gallon into your floors, so knowing where to stop it is the difference between a $150 repair and a $15,000 claim. Locate and test three levels of shutoff: the main shutoff where water enters the house (everyone in the household should know it); individual fixture shutoffs under sinks and behind toilets; and the water heater's shutoff. Test the main valve now -- old gate valves seize, and a shutoff that won't turn is a repair to schedule this month, not discover mid-flood.

Two: protect your drains and pipes

• Never pour grease down a drain -- it congeals and clogs; can it and trash it.
• 'Flushable' wipes are not flushable -- they don't break down and cause clogs and sewer backups; only toilet paper and human waste go in the toilet.
• Keep hair out of shower and sink drains with cheap screens -- hair clogs are the most common DIY drain call.
• Don't use a garbage disposal as a trash can: no fibrous scraps (celery, peels), no starchy expanders (rice, pasta), no coffee grounds in quantity.
• In freezing weather, protect exposed pipes -- a burst frozen pipe is the most expensive plumbing failure there is.

Three: handle the common failures

A few failures cause most household plumbing grief, and most are cheap DIY fixes. A running toilet -- usually a $10-15 flapper or fill valve -- can waste hundreds of gallons a day and inflate your water bill; it's the most common and most satisfying DIY plumbing repair. A clogged drain usually yields to a plunger or a hand auger (skip the caustic chemical drain cleaners, which damage pipes and rarely fix real clogs). A dripping faucet is typically a worn washer or cartridge. And a slow toilet or a phantom-flushing tank points to the same cheap flapper. Learning these three or four fixes eliminates the majority of small plumber visits.

The bottom line

Homeowner plumbing is mostly about prevention and knowing your limits, not skilled repair. Learn every shutoff and test the main one, protect your drains from grease, wipes, and hair, and master the handful of $20 fixes -- flapper, plunger, faucet washer, aerator -- that cover most small problems. Recognize the real emergencies (sewer backup, failed water heater, burst line) and call a licensed plumber for those and for anything behind walls. The knowledge is cheap; the floods it prevents are not.