I agree with all the above posts so would just add one comment, fresh bath water every day is important because in my opinion its helps the birds moult quicker which is a stressful time for them and the quicker they moult out the better. Daily baths soften the new pin feathers which makes it easier for the birds to moult, they preen themselves a lot more after bathing so get though the moult quicker, a bird with no bath water will have dry brittle feathers trying to grow out which will take a lot longer than a bird with access to fresh bath water.
Just my opinion.....