Yard Drainage Learning Center: The Concepts Behind the Fixes
Every drainage fix rests on a few basics: how water moves across and through the ground, whether your soil can absorb it, why clay behaves the way it does, and how much slope water needs to move. Understand these four and you can judge any advice you're given.
Why the basics are worth ten minutes
Most yard drainage mistakes aren't installation errors — they're understanding errors. A French drain buried under surface water, a dry well dug into clay, a low spot filled in a yard that drains poorly everywhere: each is the right tool used without grasping the concept underneath.
The pages here cover the four ideas that sit beneath every drainage decision. None of them takes long, and together they let you tell whether the advice you're reading — or being quoted — actually fits your yard.
The four concepts
- How yard drainage works — surface water versus water in the soil, and why that single distinction decides almost everything.
- How to test your soil's drainage — the one-hour perc test that tells you whether your ground can absorb water at all, and what the result means.
- Clay soil and drainage — why the soil that causes most drainage problems drains so slowly, and what actually helps.
- How much slope you need for drainage — the grade numbers, how to measure them, and why "flat" is rarely as flat as it looks.
Once these make sense, what you're seeing and which fix suits it both get much easier to sort out.
FAQs
What do I need to understand before fixing yard drainage?
Four things: whether your water is on the surface or in the soil, whether your soil can absorb water (a perc test answers this), how clay changes the picture if you have it, and how much slope you have to move water. Those four decide which solutions can possibly work in your yard, before cost or preference enter into it.
Why does understanding the basics matter?
Because most drainage failures are the right tool used in the wrong situation — a French drain for surface water, a dry well in clay. Grasping a few concepts lets you avoid those expensive mistakes and judge whether a contractor's diagnosis makes sense. Ten minutes of understanding saves thousands in misapplied fixes.
All pages in this section
Clay Soil and Drainage: Why It Holds Water and What Actually Helps
Clay drains slowly because its particles are tiny and pack tightly, leaving almost no room for water to pass — often less than half an inch an hour. That's why it causes most yard drainage problems.
How Much Slope Do You Need for Drainage?
Near the house, aim for about 6 inches of fall over the first 10 feet — roughly a 5% grade. Out in the yard, 1% is enough to move water, meaning 1 inch of drop per 10 feet.
How to Test Your Soil's Drainage: The One-Hour Perc Test
Dig a 12-inch hole, fill it with water and let it drain to pre-soak the ground, then fill it again and time how far the level drops in one hour. More than an inch an hour is good; under half an inch means poor drainage.
How Yard Drainage Works: Surface Water vs Water in the Soil
Yard drainage manages two kinds of water: water on the surface, which runs and pools where you can see it, and water in the soil, which soaks in and saturates the ground below. Different tools handle each, and telling them apart is the one distinction that decides almost every drainage fix. .
By Under Your Home Team · Last reviewed 2026-08-09