Population growth, pollution and climate change put water systems under immense pressure. The reuse of greywater for irrigation will benefit homeowners and water utilities alike. Greywater is, however, different from fresh water and requires different guidelines for it to be reused.
WHAT IS GREYWATER?
Greywater is wastewater accumulated from household use. It can be sourced from hand basins, showers, baths, washing machines and kitchen sinks 1. Water that has come into contact with faeces from the toilet or has been used for washing diapers should be avoided.
WHY IS GREYWATER IMPORTANT?
Population growth, especially rapid urbanisation, as well as pollution and fluctuations in rainfall put water systems under immense pressure.There is a general outlook that between 2015 and 2033 water demand in the already water-scarce South Africa will exceed supply2. This is of great significance, as South Africa relies on its neighbours for access to water sources and on elaborate water distribution infrastructure that uses large amounts of energy.
It is estimated that 31-50% of water consumed in South African households goes towards gardening. Besides, for example, harvesting rainfall or planting drought-resistant plants, the reuse of greywater for irrigation will benefit homeowners and water utilities alike.
BENEFITS OF REUSING GREYWATER
Saving money on your water bill
Reducing the chances of polluting local water bodies
Reconnecting urban residents and backyard gardens to the natural water cycle
GREYWATER FOR IRRIGATION
If greywater is released into rivers, lakes, or estuaries, its nutrients become pollutants, but to plants, they are valuable fertiliser. Therefore, while greywater may look “dirty,” it is a safe and even beneficial source of irrigation water for the homestead 3.
Greywater can easily be piped directly outside or distributed via buckets to water ornamental plants or fruit trees. The wastewater can also be used to irrigate vegetable plants, as long as it doesn’t touch edible parts of the plants. It is essential to use “plant-friendly” products that don’t contain salts, boron, or chlorine bleach as their build-up in the soil can damage plants 3.
6 BASIC GUIDELINES
Greywater is different from fresh water and requires different guidelines for it to be reused, as set out by the United States organisation Greywater Action 3:
1. Don’t store greywater for more than 24 hours.
2. Minimise contact with greywater.
3. Infiltrate greywater into the ground, don’t allow it to pool up or run off.
4. Keep your system as simple as possible - avoid pumps and filters that need upkeep.
5. Install a 3-way valve for easy switching between the greywater system and the sewer/septic.
6. Match the amount of greywater your plants will receive with their irrigation needs.
Harsh municipal water restrictions need not be a death sentence for gardens if households become more greywater-savvy. As citizens take responsibility for their water consumption to support municipalities, municipalities can focus on the greater task of more effectively managing their water assets. For more information on how municipalities can do this, read our blog Moving Towards Comprehensive Water Demand Management. .