The lay of the land allowed for a basement area to be built at the back of the house. This housed a storage tank. The house was not connected to mains water - by choice not necessity. All water that landed on the roof was funnelled into the gutters, down the down pipes, through pipes under the house and into the storage tank. The tank was 8 cubic metres, about one half of the basement area. If the tank filled up, the overflow was directed through pipes into the pond. The pond's only way of filling up was from the overflow or rain. Plant growth on the pond helped to guard against evaporation during hot spells.
I never ran out of water, though got low on a few occasions. The water issue was never a hardship, even once when I had a number of people staying. A lot of it has to do with awareness. Awareness of how we use water and how much we waste by just leaving taps running. I also learnt how much rain water we waste. How much rain water in our current system lands on roofs, is collected in gutters, directed down down pipes and then into the drainage system. What if we utilized our roofs to collect rain water for our own personal use or to use on the garden?