MAKE THE WATER YOU HAVE WORK HARD
Rainwater harvesting can provide a surprising amount of daily water, and even one or two 5 000ℓ rainwater tanks allow you to do spot-watering throughout the dry season. An average 200m2 house in an area with an annual rainfall of 500mm can generate 100 000ℓ of roof runoff, and even in a more seasonal area a useful amount of water can be captured in tanks.
Make sure the overflow is also replenishing soil water in a place that is useful – maybe where you want to establish a windbreak or screen, under a large tree, or even in a vegetable garden. A portable overflow pipe allows you to top up soil water where it makes sense. In dry areas, this can extend the active growing season by a month.
Make all your household water work at least twice. Soaps and detergents, however, are hard on most plants and will eventually cause the soil to become extremely loaded with alkaline salts, locking away all plant nutrients. The effect depends on the soil type, so watch plant health and move grey-water outlets around if you need to. Milkwood trees grow well throughout most of South Africa and seem to be exceptionally tolerant of grey water.