The worst is drinking out of a garden hose. If you are at a customers place and need a drink it's so tempting to grab the hose. Better you unscrew or click the hose off and have a drink.
Garden hoses laying around unused for periods of time means they're a haven for bacteria especially if a little warm.
In Adelaide back around the 90's there was a serious outbreak of meningitis ... many died. They tried to trace where and why and eventually found 2 sources.
Air conditioner cooling towers, mainly water coolers.
And the biggest culprit, black irrigation pipe.
The outbreak occurred Spring/summer when people switched on their "incubator" hose systems freely spraying the bacteria into the environment, themselves etc.
We boil our tap water, charcoal filter, then refrigerate.
But sometimes run out or forget so just be careful of hoses.