Filling a birdbath with fresh water helps the birds. But make sure the birdbath water you're using is safe for birds to bathe in and drink.
Don’t Fill Your Birdbath With Garden Hose Water—Here’s Why
Is Hose Water Harmful for Birds?

“Can I use hose water to fill birdbaths, or is the PVC harmful for birds?” asks Birds & Blooms reader Tobias Morse of Montague, Michigan.
Birding experts Kenn and Kimberly Kaufman say, “It’s true that ordinary garden hoses contain chemicals that could be harmful to birds. Besides PVC (polyvinyl chloride), the hose may contain lead or other toxins. Small amounts may leach into the water, especially when water sits in the hose for hours or days.
If you’re in a situation where the only practical way to fill your birdbath is with a garden hose, let the water run for at least a few minutes to wash out most of the contaminants. It’s also possible to buy hoses made of safer materials; look for those labeled as being safe for drinking water.”
Should you put copper pennies in your birdbath?
Can You Use Water From a Rain Barrel?

Saved rainwater can be used to irrigate your trees, shrubs and ornamental flower beds; feed into a rain garden; or wash your home or car. But because roof water can contain droppings from birds, moss and roof tile materials, it’s not recommended to use a rain barrel as a source for drinking water (for you or the birds) or for watering edible plants.
How to Properly Fill Your Birdbath

Fill a watering can or pitcher with water from your kitchen sink or another drinking water source (avoid water that is treated with softener salt). Then use the water to fill your birdbath.
Keep the water shallow (aim for a maximum depth of 1 1/2 to 2 inches) and consider adding stones for small birds to perch on.
Clean and rinse your birdbath every couple of days. Use a stiff brush to remove any dirt and debris, then add fresh water (you may need to add water more often in hot weather).
Keep offering fresh water, even in winter. You may have heard that offering water to birds in winter is dangerous, but a heated bird bath is a safe way to help keep your feathered friends hydrated.
About the Experts
Kenn and Kimberly Kaufman are the official bird experts for Birds & Blooms. They are the creators of the Kaufman Field Guide series and they lead birding trips all over the world.