You walked outside and found a soggy patch that wasn’t there last week. Now you’re wondering whether you have a drainage problem or pipe leak, and how expensive it’s about to get.
Here’s the short version. Drainage water follows the weather: it shows up with rain and fades within days. A pipe leak ignores the weather and keeps the same spot wet every day.
J&P Landscape has sorted out both kinds of wet yards across San Jose and Silicon Valley since 1984. Our drainage service covers the fixes for the first kind. If your tests point to a buried pipe, drain pipe leak detection is the next step. This guide helps you tell which one you have before anyone starts digging.
Does the Wet Spot Follow the Weather?
A drainage problem means rain or sprinkler water has nowhere to go, so it collects on or just under the surface. A hidden pipe leak means water is escaping from a buried line and soaking the soil from below.
J&P Landscape, a licensed Bay Area landscape contractor since 1984, tells a drainage problem from a pipe leak with one question: does the wet spot follow the weather? Drainage water appears during or right after rain and fades within about three dry days, because San Jose’s clay soil drains slowly but it does drain. A leaking pipe keeps feeding the same patch every day, rain or shine. The fastest check takes about 30 minutes: shut off every faucet, appliance, and sprinkler zone, then watch your water meter’s low-flow dial. If it keeps moving, water is escaping somewhere on your property, which points to a leak. If it sits still and the spot only shows up after storms, you’re dealing with drainage. A patch that’s still soggy more than three dry days after rain deserves a closer look either way, since some yards have both problems at once.
Here’s how the two compare at a glance:
| Clue | Drainage problem | Hidden pipe leak |
|---|---|---|
| When it appears | During or right after rain | Any day, rain or shine |
| How long it lasts | Fades within a few dry days | Stays wet or keeps coming back |
| Where it shows up | Low spots, fence lines, near downspouts and foundations | A small, fixed patch along a pipe route |
| Grass and soil | Muddy, sometimes mossy | Unusually green patch, soft or sunken soil |
| Water bill | No change | Unexplained rise |
| Smell | Earthy | Sewage odor points to a sewer line |
This is where Bay Area yards fool people. Santa Clara County’s expansive clay soil holds water, so even a healthy yard can stay damp for a couple of days after a storm. A patch that’s still soggy on day four is the one worth investigating.
Four At-Home Tests Before You Call Anyone
You don’t need special tools for these. Each one takes a few minutes, and together they usually narrow things down fast.
1. The Dry-Spell Check
Note the date of the last rain. Then look at the spot each morning for three days, and snap a photo each time. If it dries out, drainage is the likely cause. If it stays wet or keeps refilling, move on to the next test.
2. The Water Meter Test
Turn off every faucet, appliance, and sprinkler zone. Find your meter, usually in a box near the curb, and look at the low-flow dial. Check again after about 30 minutes.
If the dial moves with everything off, water is leaking somewhere on your side of the meter. Check your toilets first, since a running toilet can fake a yard leak.
3. The Sprinkler-Zone Check
Run each irrigation zone for a few minutes, one at a time. Watch the wet spot and the nearby sprinkler heads. If the patch gets wetter or heads in that zone sputter with weak pressure, the leak is probably on that zone’s line.
4. The Downspout Hose Test
This one only applies if your downspouts connect to underground pipes. On a dry day, run a garden hose into the downspout opening for several minutes. If water surfaces at your wet spot, the buried line is cracked or clogged.
Before you dig anywhere, call 811, at least two working days ahead. Gas, electric, and water lines share yards, and hitting one turns a wet spot into an emergency. And if the water smells like sewage or your indoor drains are slow, stop testing and call a plumber.
Where Hidden Yard Leaks Usually Hide
Most soggy-but-not-rainy patches trace back to one of three places.
Irrigation Lines
Sprinkler lines run shallow, so roots, shifting clay, and old shovel strikes can crack them. Look for a patch that grows when the system runs, weak spray, and a higher water bill. When this is the source, irrigation repair is usually a smaller job than people fear.
Buried Downspout and Drain Pipes
Many homes send roof water through underground pipes to the street or a dry well. When one cracks or clogs, water backs up and surfaces near the break. That’s what makes it tricky: it only shows during storms, so it looks like a drainage problem when it’s really a pipe problem.
On older properties, the wet spot often sits right over a line someone buried years ago and nobody remembers.
Supply and Sewer Lines
A leak in the pressurized line to your house keeps the soil wet and spikes your bill. A sewer lateral leak usually announces itself with smell. Both of these are plumbing repairs, not landscaping ones.
What a Landscape Contractor Can Fix, and What Needs a Plumber
J&P Landscape is a licensed design-build landscape company (CA Contractor License #963784), so we handle the yard side of the problem: regrading low spots, French drains, downspout runoff lines, and irrigation repair. If your tests point to the main supply line or a sewer lateral, that belongs with a plumber, and we’d rather say so up front than guess.
Plenty of yards have both problems at once. A leaking sprinkler line can feed a spot that also has no place to drain. So fix the leak first, then judge what the drainage is really doing. If the soggy spot is mostly rain-related, our guide to fixing a waterlogged backyard walks through the options.
Frequently Asked Questions
Check whether it stays wet on dry days. If the spot is soggy three or more days after rain, or your water meter dial moves with everything off, a pipe is the likely cause.
Usually a leaking irrigation line, supply line, or buried drain pipe is feeding the soil. Overwatering and runoff from a neighbor's property can also do it, so run the sprinkler-zone check first.
Yes. A cracked or clogged downspout or yard drain pipe backs up and surfaces near the break, usually during storms. A hose test on a dry day can confirm it.
A leak in a pressurized line, like irrigation or the supply line to your house, often does. A leak in a rain-fed drain pipe won't, because it only carries stormwater.
It depends where the leak is. Supply lines and sewer laterals need a plumber, while irrigation lines, yard drains, and grading issues are landscape work.
Yes. J&P Landscape serves the wider Bay Area, including Redwood City and Fremont. We offer a free consultation to sort out whether water or a pipe is the problem.
Tired of Guessing What's Wet Under Your Yard?
You shouldn’t have to wonder every time it rains. If your yard passes the leak tests, or you still can’t tell, J&P Landscape offers a free consultation for homeowners across San Jose, Silicon Valley, and the Bay Area. We’ll walk the property, separate the water problems from the pipe problems, and give you a straight quote. Call (408) 636-6442.
Related Reading: Yard Drainage Checklist for the Rainy Season · Landscape Projects