I live on a hobby farm and we've planted an orchard on our property. With the droughts that have been going on we didn't want to lose any trees. My husband came up with this idea on his own a few years ago and we even use it in the gardens now:
Go to any fast food place or a bakery and ask about getting empty pickle buckets. About an inch from the bottom, drill a 1/16th inch hole. Use a file to scrape the hole smooth and place the bucket near what ever you want to water. Make sure you point the hole toward the plant. Now, fill the bucket with water. 5 gallons a week is all a tree needs. Bakeries often have 2.5 gallon buckets from the fillings and icings or you can fill the buckets less for smaller plants like tomatoes.
I have also gotten soy sauce buckets from behind a Chinese restaurant - & florists sometimes get rid of their dirtier ones, too. What a great Idea! We have to think water conservation!!