Clean water in your birdbath helps both the birds and your property. Dirty water increases the spread of disease among birds, and it also introduces a breeding ground for mosquitoes. In addition, dirty water simply looks unappealing, both to you and to the birds.
Generally, you need to change your water at least every two to four days, but if your water quickly grows dirty, change it more regularly. If the water looks dirty or if algae grows on the birdbath itself, you haven’t cleaned enough.
When it is time to clean your birdbath, first empty out the water. Then, use a small scrub brush and mild detergent or birdbath cleaner (not bleach or chemicals) to clean off any dirt stains. Once you have cleaned out any stains, rinse out the birdbath thoroughly (birds don’t like soapy water) and refill the bath. You probably will not need to use detergent every time you change the water, but change the water at least twice a week.