Birds need clean water year round. photo only no link I have been seeing on Pinterest all week how to clean your cement birdbath. I hope and pray no one uses bleach. Simply empty out water use lemon juice 100% natural scrub bath and let sit for 10 to15 minutes. Uses a high pressure nozzle (the old fashioned bronze) should clean up nicely. After fifteen years my birds are spoiled, so they have me every week still scrubbing. I'll get off my rant and go back to the garden now.