I've stopped at churches twice to fill up water bottles and take advantage of some shade. Both times I've left money in the door. A few years ago I had to stop at a private residence and ask for water (it was a 90 mile day with 95 degree heat and I had stopped sweating). The people were very nice and refused payment. Municipal water costs around 1/10 of a penny for a gallon here so it's not like you're committing some grand larceny.