Went to a one room schoolhouse for 4th, 5th & 6th grade. Didn't have running water but did have two outhouses. A brother and sister brought in a stainless steel milk container of water (guessing about 20 gallons). Had an older woman as our teacher. 6 rows, 6 grades, about 30 students. Had no trouble learning.
A neighborhood could set up a co-op agreement and have a one room independent school.