The short answer
Standing water means inflow is exceeding the window well’s drainage path. The cause may be leaves, roof runoff, poor grading, silted stone, a blocked drain, or a drain that was never connected. Protect the basement first; do not keep adding test water when the level is near the window.
Read the pattern before digging
Check the well during or just after rain and photograph the water line. Clear loose surface debris from outside the well. Look for soil washed over the rim, a nearby downspout, a cover that funnels water inward, gaps at the foundation, and movement at the fasteners.
| Pattern | Area to investigate |
|---|---|
| Water appears only in intense rain | Roof discharge, grading, or drainage capacity |
| Water remains long after rain | Blocked stone or drain path |
| Mud coats the bottom | Soil is washing in and clogging drainage |
| Water enters at the frame | Window or flashing defect, or water rising above the frame |
| Well bows or pulls away | Anchorage, soil pressure, or freeze/thaw movement |
BILCO’s instructions specify free-draining stone around and inside its wells and describe connecting to an existing perimeter drain where one exists. Those details do not prove an older well has a working connection.
Use a controlled drainage check only when conditions are safe
Do not add test water when the drainage route is unknown, the well or foundation has moved, the window already admits water, or the water could obstruct an egress opening. In those cases, document the rain pattern and have the well and outlet traced without adding water.
If the basement is dry, the window is sound and protected, the level is well below the frame, and the visible drain has a known safe outlet, uncover only the drain surface. Add a small controlled amount of water and watch whether it disappears. Stop immediately if it ponds, approaches the window, or appears indoors. Never enter a deep well without safe access or excavate beside the foundation based on this check alone.
Correcting a downspout or grade can reduce inflow, but it will not clear a failed underground drain. A contractor may need to expose the connection or use a camera or tracer.
Escalation signs
Arrange prompt help when water touches the glass, leaks indoors, undermines the well, or blocks a required egress window. A loose, corroded, or bowed well needs structural attention before anyone climbs into it.