Did the relatives live in an area with regular rain? Catchment is always a possibility.
Yeah. The catchment filled the cistern but not enough still if it was raining a tank would last a while, but like with company over at Christmas it would mean a trip to FS every three days or so. They’re only about 2-3 miles outside of town but they didn’t get the water mains extend that far until about 2015. I forget why they couldn’t have a well.