What causes water caustics bleeding above the waterline in Unreal?

The caustics are projected by a light function or decal with no clip at the water surface, so the rippling pattern lands on rocks and walls above the water too.

How do I catch this when it only happens for some players?

Capture it automatically from the player's device with the full stack trace, the device and OS, the build, and a breadcrumb trail of what they did. That turns a vague complaint into a specific, reproducible issue you can fix without owning the hardware it happens on.

How to Fix Unreal Water Caustics Bleeding Above the Waterline

Quick answer: Mask the caustics projection to below the water height using world position, fog volume, or a depth test so the pattern only appears on submerged surfaces.

Caustic light ripples climb up onto dry cliffs above the water, which looks wrong. Caustics should be confined below the water surface; the projection needs a height or volume mask.

How to fix it

1. Clip by water height

In the caustics light function or decal material, fade the contribution to zero where world Z is above the water surface height so dry surfaces stay unaffected.

2. Or use a water volume

Restrict caustics to a post-process/volume that only applies underwater, so leaving the water automatically removes the projected pattern.

3. Tint and fade with depth

Scale caustic intensity by depth below the surface and tint with the water color so the effect strengthens deeper and vanishes cleanly right at the waterline.

Catching the ones you can't reproduce

The hardest version of this to fix is the one you can't reproduce — it only happens on a player's hardware, OS, driver, or save state, under conditions that simply aren't present on your machine. A report that says “it crashed” or “it froze” gives you nothing to act on, so the bug survives release after release while quietly costing you players.

Automatic error capture closes that gap. Each failure arrives with its full stack trace, the device and OS, the build number, and a breadcrumb trail of what the player did right before it broke, so even a failure you have never seen becomes a specific, reproducible issue. Fold identical failures into one signature ranked by how many players each hits, and your worklist sorts itself worst-first instead of arriving as a stream of vague complaints.

This is where a tool like Bugnet earns its place. Its SDK captures every Unreal Engine error automatically with the full stack trace plus device, OS, memory, build, and game-state context, folds duplicates into one grouped issue with an occurrence count, and ties each to the build it first appeared on — so you fix the problem that hurts the most players first and confirm it is gone when its signature disappears from the next release.

The errors you never hear about are the ones quietly costing you players. Visibility turns them into a worklist.