Tips for Using Greywater in the Garden

South Africa is a semi-arid country that receives an average of 490mm of rain every year. Currently, the country is experiencing a water shortage because there is only 1 000m3 of water available per person per year. This figure will decrease as our population expands, pushing us into a greater water crisis.

Use rainwater harvesting, reuse wastewater (greywater) and apply soil improvement process like composting as a means to reducing your water consumption in the garden.

Municipal water use, which includes domestic water and water used in the garden, makes up an average of 27% of the total water used in the country. A major component of domestic water consumption is gardening, estimated at 31% to 50% of total household water use.

How can you reduce your water use in the garden?

Using water wise gardening concepts and drought-resistant indigenous plants, along with mulching of soil to preserve soil moisture and efficient irrigation systems and irrigation scheduling will help reduce the amount of water you use in the garden.

You could also use rainwater harvesting and reuse wastewater (greywater) and apply soil improvement process like composting.

Why should I reuse greywater?

There are many reasons why using greywater is beneficial. Firstly, using greywater means using less of the country’s valuable potable water and saving thousands of litres of drinking water. Secondly, this will reduce the impact on natural water resources because you’ve reduced your water consumption. And lastly, you will save money on your water bill.

What is greywater? 

 Using greywater in the garden

Greywater is typically alkaline, so avoid using it on acid-loving plants such as azaleas, begonias, gardenias, hibiscus, camellias and ferns. 

Greywater should not be used on fynbos or proteas either. In general, tough, drought-tolerant plants will do best with greywater irrigation.

Greywater is typically alkaline, so avoid using it on acid-loving plants such as azaleas, begonias, gardenias, hibiscus, camellias and ferns. Greywater should not be used on fynbos or proteas either.

Plants watered with greywater will benefit from an occasional flushing of rainwater or tap water to remove any greywater residue on the plant leaves, especially if you’ve used the ‘sprayer’ system.

Pay attention to what your plants are telling you. Dry, wilted or curled leaves can be signs of lack of water, while wilted shoot tips or soft plant tissue can mean overwatering.

Examples of plants that thrive on greywater irrigation include olives, rosemary, bougainvillea, lavender, Cape honeysuckle, Italian cypress, bearded iris and petunias.

Tips for greywater use

Kitchen sink or dishwasher greywater may contain soap, detergents, grease, oils, blood, small traces of pesticides and food scraps. It should not be used for irrigation unless the water does not contain grease, blood, pesticides or oils.

Using environmentally friendly soaps, detergents and cleaning products will positively improve the quality of your greywater, and be an advantage to your garden. Also, don’t always irrigate in the same place with greywater. Constantly move the sprinkler watering system in the garden.

How plants benefit from greywater

Greywater contains small amounts of nitrogen and phosphorus, which are potential sources of plant nutrients. The soapy nature of greywater can act as a pest repellent too. 

Greywater systems

A greywater system can be very simple. For example, you can use a bucket to carry your bath water outside to water the garden. Or, you can install a state-of-the-art system that does everything for you.

The goal is to find a system that makes maximum use of your greywater, while minimising costs for the purchase, installation and maintenance of your system.

Examples of plants that thrive on greywater irrigation include olives, rosemary, bougainvillea, lavender, Cape honeysuckle, Italian cypress, bearded iris and petunias.

1. Bucket system

Use a bucket to transport the greywater, by hand, from the bathroom to the garden. It is the cheapest system but may be slightly inconvenient.

2. DIY pipe system

Connect a pipe from the outlet of your bathroom to a hosepipe. When ready, lay the hosepipe in the part of your garden that needs watering.

3. Commercial greywater system

The greywater system is connected directly to the outlet pipes of the bathroom, and the greywater is collected in a closed storage tank. The greywater is filtered to remove hair and lint. From the storage tank, the greywater is pumped into the irrigation pipes and distributed to the garden.

Health and safety greywater tips

Use a nylon stocking or a sock on the end of your drainage hose to filter out lint and hair.

1. Do not use greywater if it contains oil, faeces or urine.

2. Only store your greywater for a maximum of 24 hours.

3. Don’t let kids or pets play in or around greywater.

4. Use a nylon stocking or a sock on the end of your drainage hose to filter out lint and hair.

5. Don’t use greywater in a mist system (pathogens can be dispersed in the mist) or in a drip system (particles will clog the drip nozzles).

Article courtesy of Water Wise.