Young men lounge on patchy grass and street corners in Bonteheuwel on the Cape Flats. In this barren landscape, Lilyhaven Place is a green oasis, with a vegetable and herb garden that is thriving on a grey-water system.

The NGO Urban Harvest installed the old-age home's system to save water and nourish the food garden on which residents depend for nutrition.

Spinach, green peppers and herbs stand tall there despite Cape Town being hit by its worst water shortages.

Gardener Nkosi Nqazeleni showed off the small-scale wetland with reeds, which filters water collected from sinks and washing machines. This purification system makes the water safe for food cultivation.

Lilyhaven has more than 100 residents, and they chimed in with praise for the fresh, organic produce. Basking in the sun, 61-year-old Annette Funk said: "I like the green beans and we know it's good for us."

Urban Harvest founder Ben Getz said gardens had nutritional, ecological and spiritual value, but a suburban garden needed anything from 5000 to 10000 litres a day to flourish.

"For me gardens are not a luxury, they are a necessity," said Getz. "With the current water shortages it is really important to find ways to keep food gardens alive."

Urban Harvest has started more than 300 food gardens in Cape Town since 2006.

Said Getz: "We work with a lot of schools and community projects and have started putting in beautiful grey-water systems to support this. The systems produce odourless, colourless water which is almost good for drinking."