The water is pink / magenta
Check that the project uses URP and that the correct pipeline asset is assigned in Project Settings → Graphics. A pink material can also indicate a shader compilation problem; check the Console.
Reflections don't show anything
Make sure objects are on layers listed in the reflected layers list. Find layer indices in Edit → Project Settings → Tags and Layers.
Simulation doesn't react to objects
Objects need an Obstructor component and both obstructions + simulation must be enabled.
Water looks different in Tilemap mode
Tilemap UVs scale with bounds. Adjust tiling settings to compensate.
Performance is poor on mobile
Switch to Mobile type, reduce simulation resolution, disable or lower reflection resolution.
Camera.main is null errors
Your camera needs the MainCamera tag.
Can I have multiple water objects?
Yes. Each creates its own material instance. Managers are shared.
Can I use infinite water?
Yes — use the Advanced simulation type. It runs in world-space and follows the camera at constant cost.