A small opening along the bottom of a window can look like unfinished work. It may instead be part of the window’s drainage system. Before filling it, identify what the opening is supposed to do.

This guide focuses on drainage openings in the window itself. Water entering through the surrounding wall, or dripping from the head of the opening, needs a different investigation.

Water in a track is not the same as water on the wall

Pella’s owner manual explains that some products allow water to collect in the sill or track before it exits through weep holes. The manual recommends checking these openings for obstructions and using a small soft brush to clear them. Locations differ by product; do not assume an unfamiliar opening is a defect or a drain.

For the homeowner, location is the useful first observation. Record whether water stays within a designed track, spills onto interior trim, or appears on the wall below. Those descriptions help distinguish a drainage question from a broader leak.

Identify the window before cleaning it

1. Find the brand and product label, if accessible. Photograph it for the manufacturer’s support team.
2. Look up the care instructions for that window series. Use its drainage diagram rather than copying a different window’s layout.
3. From a safe position, inspect the accessible track and identified outlets for loose dirt or debris.
4. Use only the cleaning method allowed by the manufacturer. Do not drill new holes, force tools into concealed channels or remove unfamiliar covers.

Do not lean outside or climb to reach an exterior outlet. An inaccessible drain is a reason to arrange service, not to improvise access.

Before painting or sealing nearby

Pella’s finishing guidance specifically cautions against getting paint in weep openings. Keep identified drainage paths clear when planning work. If someone proposes sealing an opening, ask them to show its function in the product instructions first.

That question separates two tasks often grouped together as “sealing the window”: maintaining intended drainage and closing an unintended gap. The same material is not an answer to both.

If water returns after cleaning

Save photos showing the whole window and the exact wet area. Note the date, whether rain was wind-driven, and how long water remained. A clear outlet does not prove that flashing, installation or the rest of the frame is sound.

For water reaching the room, follow our window-sill leak guide. For questions to put to an installer, read about window flashing and sill pans. Moisture that forms on the glass without rain belongs in a separate discussion: window condensation.

Bring the product details and photos to the manufacturer or window contractor. A specific drainage complaint is easier to investigate than a request to caulk every visible opening.