This article is brought to you by AskBobCarr.com — Maryland’s trusted source for practical water solutions, smart drainage diagnosis, and real talk from Bob Carr.
Hi, I’m Bob Carr. I’ve been walking Maryland properties for over 35 years. And before we break out the trenchers, pipes, or drawings, there’s one thing I always do first:
I test the soil.
Because 90% of drainage problems I see? They come down to this: the ground can’t take the water. And I’ve got a five-minute test that tells me what I need to know.
Let me show you how it works — and why it matters more than any other tool in my truck.
What You’ll Need
This isn’t complicated. You don’t need fancy lab gear or machines. You just need:
- A post-hole digger, auger, or shovel
- A bucket or garden hose
- A watch, phone, or stopwatch
- A ruler or tape measure (optional but helpful)
This test is often called a “perc test” — short for percolation. It tells you how fast water moves through your soil.
The TLC Water Absorption Test (Step-by-Step)
- Pick your location. Go to the wettest part of your yard — where water sits the longest.
- Dig a hole at least 12” deep and 6” wide. You can go deeper if you suspect deeper compaction.
- Fill the hole with water and let it fully drain. This pre-wets the soil to simulate real storm conditions.
- Refill the hole a second time and start your timer.
- Check the water level every 30–60 minutes. Track how many inches drop per hour.
Repeat this in more than one location if you want to compare zones. Front yard vs. back. Shady areas vs. sunny ones. It can vary more than you think.
What Your Results Mean
More than 1” per hour
Great news. Your soil drains well. You likely don’t need a complex drainage system — just proper grading and water redirection.
Between 1” and 0.25” per hour
Moderate absorption. Your soil is slow, but workable. You’ll want to use solid drain pipe, sandier backfill, and protect against sediment.
Less than 0.25” per hour
Now we’re talking clay, compaction, or construction fill. This soil holds water, suffocates roots, and causes long-term headaches. A French drain alone won’t fix this — we need to rebuild the soil.
AskBobCarr.com Tip: If your soil drains less than a quarter inch per hour, we recommend a combined soil rebuild + drainage strategy. That means pulling out the poor material, adding sand and compost, and making sure water has somewhere to go.
Why This Test Saves You Thousands
Most drainage contractors skip this part. They eyeball a puddle, quote a French drain, and dig. That’s how you end up with expensive systems that don’t work.
I don’t believe in guessing. I believe in knowing.
This test: – Tells us how deep we need to dig – Shows if water will soak, drain, or spread sideways – Lets us choose the right fix (not the most popular one)
Field Story: Edgewater, MD
We had a client with a wet backyard and standing water. Another company had installed a French drain — but it failed in a year.
We ran this test. Drain rate: 0.1” per hour.
Our AskBobCarr.com fix: – Removed 10” of soil across 800 sq ft – Mixed in compost, loam, and sand – Added a new drain system tied to a pop-up emitter
Result: Dry lawn. No standing water. And a system that actually moves the water.
Field Story: Davidsonville, MD
This family had water always pooling near their driveway after storms. Contractors told them it was slope — but we knew to check deeper.
Drain rate was under 0.2” per hour. No wonder the lawn never dried out.
Our fix: – Soil rebuild with compost and sand blend – Installed a shallow French drain 10” deep with a 2% slope – Directed water 40 feet to a safe exit with a pop-up
Result: No more driveway ponding. Grass regrew in 3 weeks. Problem gone.
What It Costs to Fix Based on Your Soil Test
|
Drainage Strategy |
Typical Cost Range |
|
Minor grading & downspout reroutes |
$1,000–$3,000 |
|
Soil rebuild (per 1,000 sq ft) |
$3,000–$6,500 |
|
French drain w/ soil correction |
$6,000–$12,000 |
|
Dry well w/ overflow & fabric protection |
$2,500–$4,500 |
|
Pop-up emitter install (w/ slope) |
$800–$2,000 |
Bob’s Note: We don’t overdesign. We do what works, and we often phase work if you want to start with the worst zone first.
FAQs About Soil Drainage Testing
Q: Do I need to test in multiple spots?
A: It’s a good idea, especially if your front and back yards behave differently.
Q: What if my soil drains great — but I still have puddles?
A: That likely means you have a grading or flow issue, not a soil problem. We fix that, too.
Q: Can I do this test in winter or early spring?
A: Yes, but thawed ground works best. Fall is ideal — before the freeze sets in.
Q: Will a French drain work if my soil drains slowly?
A: Only if we prep the trench right. That’s why we wrap our drains in filter fabric and backfill with the right gravel blend.
Q: How long does it take TLC to run this test?
A: We do it on every water evaluation. It takes 5–10 minutes and gives us all the insight we need to build a smart plan.
Final Thoughts From Bob
I’ve said this for years — before you build a system, test the soil.
Because it’s not just about what you see. It’s about what’s underneath — and how water behaves once it hits the ground.
This one simple test has saved homeowners thousands. And helped us design better, smarter, longer-lasting solutions.
📞 Call (410) 721-2342 or schedule your soil and drainage check at AskBobCarr.com
Because fixing drainage starts by understanding how your soil holds — or hides — water. And that starts with a bucket, a hole, and five minutes of truth.