Pipe & fitting basics
Pipe & fitting basics
PVC, CPVC, PEX and copper — what each one is for, in plain English.
Pipe & fitting basics, in plain English
Most plumbing repairs come down to knowing which material you're working with and whether the line is under pressure. Here's the vocabulary printed on every fitting in the aisle.
Supply vs. drain
Supply lines are pressurized and small; drain lines are gravity-fed and large. Parts are never interchangeable.
PVC
White rigid pipe for cold water, drains, irrigation and pool lines. Solvent-welded — never used for hot supply.
CPVC
Cream or tan pipe rated for hot water supply. Uses its own cement, not standard PVC cement.
PEX
Flexible tubing for hot and cold supply. Joined with crimp rings, clamps or push-fit — no torch.
Copper
Soldered or press-fit rigid supply. Still common in older Delray homes; repairs often transition to PEX.
Compression fitting
A brass nut and ferrule that grips the tube. No glue, no solder — just don't overtighten.
P-trap
The U under the sink. It holds water to block sewer gas, which is why a dry guest bath smells.
Angle stop
The little shut-off under the sink or toilet. Exercise it once a year so it still turns when you need it.
Vacuum breaker
Backflow protection on hose bibs and irrigation — required so garden water can't siphon back inside.
Shut the water off at the fixture stop — or the main — and open a lower faucet to drain pressure before you take anything apart. Keep a bucket and a towel underneath regardless.