Quick troubleshooting screen
Choose the closest symptom and what you can observe during rain. The result is an inspection order, not a remote diagnosis.
1. If the outlet is unknown, find it before replacing anything
A collection system with no known endpoint is difficult to diagnose. Trace visible piping, cleanouts, daylight outlets and discharge points. If the system was intended to infiltrate rather than discharge, identify the storage/infiltration feature and how overflow was supposed to work.
An unknown outlet is especially important when a drain appears to “take water” at the inlet but the wet area never improves. The problem may be downstream, not at the grate or trench.
2. If performance gradually worsened, inspect maintenance points first
Leaves, mulch, sediment and root growth can reduce surface inlet area or block a downstream opening. A catch basin may need the grate and sump cleaned. A daylight outlet may be buried by vegetation or sediment. A downspout screen can also restrict flow before water ever reaches the buried line.
Do not force tools into buried pipe or use high-pressure methods where you do not know the pipe material, joints or downstream condition. Access strategy depends on the actual system.
3. If it only fails in large storms, separate capacity from blockage
A system that works during ordinary rain but is overwhelmed during larger events may be reaching its hydraulic or storage limit rather than being fully blocked. Look for strong outlet flow during the failure. Visible discharge plus upstream overflow suggests a different question from an outlet that remains dry.
Wrivel's volume calculators can compare event volumes, but they do not calculate peak pipe capacity. Inlets, pipe diameter, slope, fittings and storm intensity all influence flow rate.
4. If a French-drain strip stays wet after several rainy days
Persistent saturation after consecutive wet days can reflect slow soil, a high seasonal water table, an undersized or restricted outlet, or water entering from a source the trench was never meant to intercept. A gravel trench is not evidence that surrounding soil can always absorb the inflow.
Compare observations at the proposed/installed area with the soil drain-down field worksheet, while remembering that a simple field observation is not a formal design infiltration test.
5. If a downspout backs up
Start upstream and move downstream: gutter/downspout blockage, connection fitting, accessible cleanout, buried route and outlet. If the line has always backed up, verify whether it has continuous fall. If it worked before and changed suddenly, obstruction or a changed outlet condition deserves attention before upsizing.
Use the downspout drainage guide to compare roof runoff volume with the measured route geometry.
6. If the outlet is eroding the yard
The system may be moving water successfully but releasing it with too much concentrated energy for the outlet area. Extending the pipe a few feet is not automatically a fix. The receiving surface, slope, velocity, stabilization and legal discharge location all matter.
Active erosion near a slope, retaining wall, foundation or public infrastructure can become a higher-consequence condition and may need local professional review.
7. If the same puddle remains but the outlet flows
Check whether the inlet is actually at the low point and whether surrounding grade directs water to it. A functioning pipe cannot collect water that never reaches the inlet. Broad sheet flow may need surface shaping, while a point low spot may need inlet elevation corrected.
A simple maintenance rhythm
Before excavating an existing system
- Find the actual outlet or infiltration endpoint.
- Inspect all accessible inlets, grates, screens and cleanouts.
- Observe the system during rain if it is safe to do so.
- Compare small-storm versus large-storm behavior.
- Check whether the wet area is still the lowest point.
- Locate utilities before any diagnostic excavation.
- Document pipe material and approximate route before opening the trench.