PVC pipe

What Is PVC Pipe?

PVC pipe is a rigid, thermoplastic tubing made from polyvinyl chloride. It’s widely used in residential and light commercial projects because it’s affordable, easy to cut and glue, and resistant to corrosion from water and many chemicals. PVC is commonly sold in 10- and 20-foot lengths, with diameters measured by nominal size (the size printed on the pipe). Two big ideas guide selection: whether the pipe is pressure-rated and what wall thickness it has, often shown by its schedule number (like Schedule 40 or Schedule 80). Most joints are made by solvent welding—using primer and cement to chemically fuse the pipe and fittings into a single, leak-resistant assembly.

Temperature matters: standard PVC handles cold to moderately warm water but is not meant for hot water lines. It also doesn’t love direct sunlight for years without protection, so outdoor runs usually need paint or a UV-rated product.

Common Uses in DIY and Home Projects

• Drains, Waste, and Vent (DWV) plumbing: Under sinks, in walls, and through roofs for vent stacks.
• Irrigation and sprinkler systems: Cold water supply lines and branch lines in yards and gardens.
• Outdoor water features and ponds: Manifolds, returns, and low- to medium-pressure lines.
• Shop dust collection and central vacuum runs: Smooth interior walls reduce friction and clogs.
• DIY builds and fixtures: Garden trellises, storage racks, light-duty frames, and seasonal decorations.
• Electrical conduit (PVC, gray): Protecting electrical wires underground or outdoors (use conduit-specific PVC, not water pipe).

Types and Variations

• Schedule 40 PVC (white): The most common pressure-rated pipe for residential work. Good for cold water irrigation and general plumbing where allowed by code. Lighter and easier to cut than Schedule 80.
• Schedule 80 PVC (dark gray): Thicker walls and higher pressure rating. Used for pump rooms, compressor water feeds (not compressed air), and situations needing extra durability. Heavier and usually costlier.
• DWV PVC (white, non-pressure): Designed for drains, waste, and vents. It’s not pressure-rated and uses specialized fittings (like long-sweep elbows) to keep flow smooth and reduce clog risk.
• CPVC (chlorinated PVC, tan/cream): For hot and cold potable water. Different cement and fittings than standard PVC; don’t mix them. If the line carries hot water, choose CPVC or another approved material.
• Furniture-grade PVC (usually white or colors): Glossy, UV-resistant, no printing, and often impact-resistant. Great for DIY frames and outdoor projects, but typically not pressure-rated for plumbing.
• Electrical PVC conduit (gray): UV-resistant and made for wire. It’s not rated for drinking water and uses conduit fittings. Bends can be made with a heat gun or factory sweeps.
• Flexible PVC (black or white): Bends around obstacles and reduces fittings. Common in pool and pond work. Requires compatible cement labeled for flex PVC.
• Cellular-core (foam-core) PVC: Lightweight pipe for DWV only. Not suitable for pressure applications.

Key markings to check on the pipe include: nominal size, schedule, ASTM standard (e.g., ASTM D1785 for pressure pipe), NSF ratings (e.g., potable water), and pressure/temperature limits. Most PVC is limited to around 140°F; beyond that, strength drops quickly.

Selecting, Cutting, and Joining PVC

Selecting the right pipe and fittings
- Match the application: DWV for drains/vents; Schedule 40 or 80 for pressurized cold water; CPVC for hot water; gray conduit for electrical.
- Confirm local code before buying; some areas restrict PVC for interior potable water or require specific fittings.
- size matters: Larger diameter reduces friction losses in irrigation. Remember that a higher schedule number thickens the wall, shrinking the inside diameter.
- For sunlight exposure, use UV-rated products or plan to paint with a light-colored exterior latex paint.

Cutting and prepping
- Use a ratcheting PVC cutter for 1 inch and smaller, or a fine-tooth saw/miter box for larger sizes.
- Deburr and chamfer the cut end with a deburring tool or utility knife. A slight bevel helps the pipe slide into the fitting without scraping off cement.
- Dry-fit everything first and use a marker to draw alignment marks across joints.

Solvent welding (gluing)
- Clean and prime: Apply PVC primer (often purple for inspection) to both the pipe end and the fitting socket.
- Cement both surfaces: Use the right body type (regular, medium, or heavy) for your pipe size and the correct formulation (PVC vs. CPVC vs. flex PVC).
- Assemble quickly: Push the pipe fully home with a quarter-turn twist and hold 15–30 seconds so it doesn’t push back out.
- Wipe excess and allow cure time: Follow the cement label for temperature- and size-based cure times before pressure testing.

Threaded joints
- Use factory-threaded fittings and adapters; do not cut threads into plain PVC pipe.
- Wrap male threads with PTFE tape (2–3 wraps), then snug with a wrench. Avoid over-tightening, which can crack fittings.

Support and expansion
- Support horizontal runs every 3–4 feet for small diameters and every 4–5 feet for larger diameters.
- Allow for thermal expansion on long runs with expansion joints or offsets.

Maintenance and Longevity

• Periodically inspect exposed lines for UV damage, chalking, or brittleness; paint or shield as needed.
• For irrigation systems in freeze-prone climates, blow out or drain lines before winter.
• Keep solvents, oils, and fuels away from PVC. Clean with mild soap and water.
• If a glued joint leaks, replacement is usually better than trying to reglue; use a repair coupling if space is tight.

Common Mistakes to Avoid

• Using PVC on hot water or steam lines instead of CPVC or other approved materials.
• Skipping primer or using the wrong cement type.
• Rushing cure times, then pressurizing the system too soon.
• Mixing DWV fittings into a pressure system; DWV elbows and tees are not pressure-rated.
• Not chamfering or deburring cuts, which can scrape off cement and weaken the joint.
• Using PVC for compressed air; if it fails, it can shatter. Use proper air-rated piping.
• Leaving white PVC in full sun without paint or UV protection for years.
• Threading plain PVC pipe or overtightening threaded joints.
• Incorrect slope on drains (typical target is about 1/4 inch per foot) leading to slow drainage and clogs.

Related Terms

• CPVC: Hot water–rated chlorinated PVC.
• ABS: Black plastic pipe commonly used for DWV.
• PEX: Flexible tubing for water supply lines.
• DWV: Drains, waste, and vent system.
• Solvent cement and primer: The glue and preparatory cleaner used to bond PVC.
• Schedule: Wall thickness designation affecting pressure rating and inside diameter.
• No-hub/Fernco coupling: Rubber coupling with clamps used for repairs and transitions.
• Cleanout: Access point for clearing clogs.
• Trap and vent stack: Key DWV components that block sewer gas and balance air pressure.

Practical Examples

• Repair a lawn sprinkler lateral: Cut out a cracked section of 3/4 inch Schedule 40, dry-fit new pipe and two couplings, mark alignment, prime and glue, then wait the recommended cure time before turning water back on.
• Build a garden trellis: Use 1/2 inch furniture-grade PVC with tees and elbows to form a rectangular frame. Add netting, then secure the base with rebar stakes driven into the soil and slipped into the pipe ends.
• Replace a sink drain trap: If your home uses PVC for DWV, swap a leaking P-trap by matching diameter and trap style. Hand-tighten slip-joint nuts with new washers; do not glue slip-joint connections as they’re meant to be serviceable.

Before any plumbing project, verify local code requirements and obtain permits where needed. Choose the right pipe type, make clean, well-primed joints, and support runs properly—your installations will last longer and stay leak-free.