Wrap a French Drain Properly
Wrapping the fabric around the stone bed and pipe together, not just the pipe, so dirt cannot migrate in and clog the drain over time.
Lay French Drain Pipe Holes-Down So It Starts Draining Sooner
Technique: French Drain Pipe Orientation
The Problem
Perforated drain pipe has holes along one side, and the instinct is to lay it holes-up so rain falling into the gravel drops into the pipe from above. It looks right and it is the way a lot of French drains get installed.
It misreads where the water is. A French drain is not catching water on its way down through the stone; it is intercepting groundwater moving sideways through the soil, and that water arrives at the trench and fills it from the bottom.
The Technique
Lay the pipe with the perforations facing down, against the stone bed.
Water reaching the trench floor can enter the pipe immediately, at the lowest point in the system. That is what lets the drain pull the water table down — it starts removing water at the level the water is actually sitting at.
Holes-up inverts that. Before a single drop enters the pipe, the water in the trench has to rise past the full diameter of the pipe and over the top of it. Everything below that line stays where it is, which is the part of the ground you were trying to dry out.
The gravel around the pipe does the rest of the work: it holds open a path for water to move through the trench faster than it moves through soil, and it filters the coarse material out before it reaches the perforations.
Pro tip: This is specific to a drain whose job is lowering a water table — a wet lawn, a soggy low corner, a slope shedding groundwater. Footing and perimeter drains around a foundation are sometimes specced differently depending on what the engineer wants the pipe to do, and pipe perforated the whole way round sidesteps the question entirely. If your drain is tied to a structure or an inspection, install what the spec says rather than what the internet says.
Pro tip: Orientation is one of two things that decide whether a French drain still works in ten years. The other is how the fabric is wrapped — wrapping the stone and pipe together as one unit rather than putting a sock on the pipe alone is what stops the stone bed silting up from outside.
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