We didn't know it but we've been supplying the neighbors with water
For the past 11 months we've been supplying water to the neighbors next door and we didn't discover it until today. We thought we had a bad leak somewhere for the past couple of weeks because every day our water tank (2000 liters) would be nearly empty within 24 hours. Last Thursday I found a pipe that went out the back past the elder's kitchen, perhaps used to water a garden in the back at one time, and thought that there might have been a break in that line. So we had a plumber put in a stop-cock Friday.
Today I took a couple of papaya to the neighbors since we had plenty, and they pointed to our water tank and tried to tell me that they needed water. They brought me back to the back of where they live and pointed to a sink and said they were now getting no water. Since both we and the elders use less than a sixth of a tank in a couple of days of normal use, I'm guessing that the neighbors have also been watering their crops with our water.