Plants need watering the summer. I have been using my bathwater (cooled down) for watering and this is economical and eco-friendly. I use bio-degradable and organic soaps so I am guessing that the water should not harm the plants in any way. In fact, soapy water kills off certain bugs and pests so this is a double benefit.  Here is a wiki article-

http://www.wikihow.com/Make-Soapy-Water-Garden-Spray

Street plants need water too although their roots absorb a lot of water from underground.  In the summer, the watering pipes stuck into the soil help the local council to water trees as the soil may be very dry.  However, lately I have been finding people putting rubbish into these pipes- sweet wrappers, paper, cans and here in this photo, a plastic bag full of dog poo.   This is so silly and selfish.  If you see anyone doing this, please explain the reason why the pipe is there- they may not know.  Already plastic is choking our seas and killing animals, now we are choking plants with plastic too.