Direct answer: If an exterior drain holds water all year, the usual causes are a blocked outlet, a low spot in the buried line, or a drain layout that was never pitched enough to empty fully. A little water in a catch basin is normal. A buried pipe that stays full is not.
Most likely: Start by figuring out where the water is standing. Water only in the basin points to normal sump depth or a clogged grate area. Water sitting deep in the pipe points to a blockage, crushed section, root intrusion, or a line that has settled and lost slope.
This one fools a lot of homeowners because some exterior drains are supposed to show a little water at the bottom, while others should run nearly empty between storms. Reality check: a drain that stays wet is not automatically failed, but a drain pipe that stays full season after season usually has a restriction or pitch problem. Common wrong move: digging up the middle of the yard before checking the outlet and measuring how high the standing water actually sits.
Don’t start with: Do not start by buying pipe or pouring drain chemicals into the yard drain. Most of these jobs are solved by finding the outlet condition and the water level pattern first.
You lift the grate and see a few inches of water below the pipe openings, but the incoming and outgoing pipe mouths are not submerged.
Start here: Start with Step 1 to see whether you are looking at normal basin sump water or a debris shelf hiding the outlet.
The pipe opening is partly or fully underwater even in dry weather, or a stick dipped into the pipe comes back wet several inches in.
Start here: Go to Step 2 and compare the water level at the basin to the outlet end of the line.
Water eventually moves, but the basin or pipe stays half full for days or weeks after weather clears.
Start here: Go to Step 3 because partial clogs and settled pipe runs often show up this way.
You see soft ground, greener grass, or a wet strip above where the buried line likely runs.
Start here: Go to Step 4 because that points more toward a crushed, separated, or sagged section than a simple grate clog.
Many exterior catch basins are deeper than the pipe openings so grit can settle below the flow path. That lower pocket may always hold some water.
Quick check: Remove the grate and look at the outlet pipe opening. If the standing water is below that opening and the basin drains after rain, the basin itself may be behaving normally.
The outlet end is where leaves, mulch, mud, rodent nests, and matted grass stop flow. When the outlet is restricted, the whole line can stay backed up.
Quick check: Find the daylight outlet or pop-up emitter and see whether it is packed with debris, stuck shut, or buried under soil.
Sediment, roof grit, roots, and washed-in debris can narrow the pipe enough that water lingers year-round instead of clearing between storms.
Quick check: Run water from a hose into the basin and watch the outlet. Weak flow, delayed flow, or dirty backwash points to a restriction in the line.
If the pipe has a belly or a damaged section, water collects in that low spot all the time even when the outlet is open.
Quick check: Look for a consistently soggy strip, sunken soil, mower rutting, or one section where probing suggests the line dropped lower than the rest.
You want to separate a normal basin sump from a true drainage failure before you chase clogs or start digging.
Next move: If the water sits below the outlet opening and the basin is otherwise clear, you may just be seeing normal sump water. Move to Step 5 to confirm the system still drains properly. If the outlet opening is submerged on a dry day, the line is holding water where it should not.
What to conclude: Water below the pipe opening usually means normal sediment sump depth. Water at or above the pipe opening means backup, poor pitch, or a blocked outlet.
The outlet is the fastest, least destructive place to catch the most common failure. If the end is blocked, the whole run can look like a buried pipe problem.
Next move: If clearing the outlet lets the line drain down and you get a steady discharge, the main problem was at the end of the run. If the outlet is open but little or no water arrives, the restriction or low spot is farther upstream.
What to conclude: A blocked outlet is common and usually fixable without digging. An open outlet with no response points to a buried clog, root intrusion, or a pipe that has settled.
A line that is merely slow behaves differently from one that is ponding because of a belly or obstruction.
Next move: If flushing restores strong flow and the standing water level drops below the pipe opening, you were dealing with a soft clog or sediment buildup. If the line takes water but always settles back to the same high level, that is more consistent with a sagged section or a stubborn obstruction.
When the outlet is open and flushing does not change the standing level, the pipe run itself becomes the likely problem.
Next move: If you identify one localized low or damaged section, you have a focused repair area instead of guessing at the entire line. If there are no surface clues but the line still holds water, you likely need a camera inspection or selective excavation starting near the first suspected low point.
Once you know whether the issue is normal sump water, an outlet problem, a clog, or a damaged section, the repair path gets much simpler and cheaper.
A good result: You should see the basin drain down after testing, the outlet discharge clearly, and no standing water above the pipe opening on a dry day.
If not: If the water level stays high with an open outlet and no visible debris, stop guessing and get the buried line inspected before buying more materials.
What to conclude: The right repair is usually small and targeted. The expensive mistake is treating every wet basin like a whole-system failure.
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Sometimes, yes. A catch basin often has a lower sump area beneath the pipe openings that stays wet so grit can settle out. What is not normal is water standing up in the pipe opening itself on a dry day.
A clog usually gives weak outlet flow, dirty backwash, or improvement after cleaning and flushing. A sagged pipe often settles back to the same water level every time, even when the outlet is open and the line has been flushed.
Not first. Try to locate the outlet by following slope, looking for a pop-up emitter, or tracing where the line should daylight. If you still cannot find it and the drain stays backed up, a pro inspection is cheaper than blind digging in the wrong spot.
Yes. Roots can enter joints or damaged sections and create a partial blockage that never fully clears. If you have trees near the run and the outlet is open but flow stays poor, root intrusion is a real possibility.
It can if the lid is stuck shut, buried in soil, or sitting in a low muddy pocket that never opens cleanly. The emitter should open easily under flow and close again when the line is empty.
Yes, if the outlet is open and you can watch where the water is going. Use moderate flow, not full blast. Stop immediately if water backs up toward the house or starts surfacing from the yard.