Can I keep an unattended birdbath clean?

I live in Portugal, in countryside about 60m North of Lisbon. We have very wet winters but it gets dry in the late spring and summer, so a birdbath is important for our locally nesting birds.

I have a birdbath which has remote filling. I have set up a webcam close to it and can refill the birdbath remotely when needed. I normally clean out the birdbath about every two weeks.

However, I will be away for several months in the summer and want to know whether to leave the birdbath in place or or not. I can regularly refill and thus change the water but won't be able to clean it by hand. Will that be unhealthy for the birds? Typical visitors/bathers are: blackbird, goldfinch, black redstart, serin, greenfinch, blue tit, house sparrow, collared dove, blackcap, sardinian warbler, white/pied wagtail and, occasionally, waxbill.

If it is not safe to leave the birdbath unattended, I can just have the water tube as a an occasional source of running water but it will be ver ysporadic and for short periods (it's part of the irrigation system for our garden).

Thanks for your advice!

Black redstart after a bath

Male black redstart after his bath