Perforated vs. Solid Drain Pipe: When to Use Each

Two Pipes, Two Opposite Jobs

Walk into any home center and you'll find drain pipe with holes and drain pipe without. They look almost identical and cost about the same, but they do opposite things — and using the wrong one is one of the most common reasons a drainage system fails. The holes aren't a minor feature. They define what the pipe is for.

This guide explains the difference, when to use each, and how the gravel and fabric around the pipe make it work. It pairs with our Oregon drainage guide, which covers full system design.

Perforated Pipe: Built to Collect

Perforated pipe has slots or holes along its length. Its job is collection — letting water from the surrounding soil seep in along the entire run. That's exactly what you want at the bottom of a French drain or a footing drain, where the goal is to pull water out of saturated ground.

Two common styles:

• Rigid perforated PVC — smooth-walled, slotted pipe. It resists crushing, flows well, and is easier to keep clean. The slots usually point down so water rises into the pipe from below.
• Corrugated perforated pipe — flexible, ribbed, and inexpensive, often sold with a sock. Easy to install around curves, but the ribs catch sediment and it's more prone to crushing under load.

Perforated pipe belongs anywhere the purpose is to gather water from the soil. See our French drain cost in Oregon and foundation drain installation cost guides for where it's used.

Solid Pipe: Built to Convey

Solid pipe has no holes. Its job is conveyance — carrying water from one place to another without losing any along the way. You use it to move collected water to the outfall, to carry clean roof runoff from downspouts, and anywhere you want water to stay inside the pipe until it reaches its destination.

Here's the rule that catches people: the run from your French drain to the daylight point should be solid pipe, not perforated. If you used perforated pipe there, the water you just collected would leak right back into the ground before reaching the exit. Our how to daylight a drain guide covers this transition.

The Typical System: Both, in Sequence

A well-built drain often uses both pipes in one run:

1. Perforated pipe in the gravel trench, collecting water from the soggy area.
2. A transition to solid pipe once the trench leaves the wet zone.
3. Solid pipe carrying the water to a daylighted outfall, dry well, or permitted connection.

Collect with perforated, convey with solid. Keep that straight and half the system is already right.

The Gravel Envelope and the Sock

Perforated pipe doesn't work alone. It sits in a gravel envelope — clean, washed drain rock that creates void space for water to move freely into the pipe. The gravel does as much collecting as the pipe itself.

The enemy of this whole arrangement is fine soil. Silt and clay particles wash into the gravel, fill the voids, and eventually clog the slots — and in Oregon's fine-grained soils, this happens fast without protection. Two defenses:

• Filter fabric (geotextile) lining the trench, wrapping the gravel so soil can't migrate in while water still passes through.
• A sock — a fabric sleeve fitted directly over the perforated pipe.

Best practice in fine or clay soils is usually fabric around the gravel envelope. A sock alone can blind over with clay; in clean, sandy soils it may be enough. Skipping fabric entirely is the single most common cause of a French drain silting up and dying within a few years.

When to Use Each: Quick Reference

A Note on Pipe Direction and Strength

For perforated rigid pipe, orient the holes so water enters as intended (commonly slots down for groundwater collection). And mind the load: anywhere pipe runs under a driveway or parking area, use solid pipe rated for the traffic, since thin corrugated pipe can crush. Crushed pipe is a silent failure — everything looks fine on the surface while the drain quietly stops working underground.