We never give ours tap water, but ours also had giardia in it at one point, and our birds ended up with it. We got rid of it, but we have never gone back to the tap for their water. We get ours in gallon jugs and I buy about 12 at a time so I have it for a while. We do the same for our cat too, and haven't had a problem since.
Hope this helped!
Thank you for my wonderful signature Deb!!!
RIP Pepper, Peatri, Holly, Mini, and Quarty