Have you ever thought of rainwater harvesting?
Installing a water butt, or any large tub, pot, bowl, etc. in the garden or the terrace is the easiest and cheapest way to make use of free rainwater for watering the garden and washing the car.
You can also divert water from gutters and from shed roofs. You can leave gardening trugs and buckets in the open to collect all the water that can be used for indoor plants, washing vessels etc. Invest in an extra large butt or a stone pot. You will feel good just saving water for the planet to survive a little longer!