2 problems with outside taps, an old neighbour had one with ahose pipe reel connected to it, one day she had a row with some neighbours kids, so they went round that night , put the hose pipe through the letter box and turned it on, result, seriously floded house.
A custonmers house in the heat wave a few years ago, left the neighbour a key, neighbour decided to water the lawn, and left the hose on for what must have been a considerable time, as the day after they got back from holiday, i went round to fix a door for them, standing in the kitchen looking down the huge garden i noted the large water feature, and flooded lawn and plants, the home owner turned into Basil Fawlty as he ran out,to turn off the water.
A few days later went back and it appeared the neighbour had left the tap running for a few days and run up a large bill on their water meter.
Always fit an off tap inside the house.