Philip Johnson’s name may be familiar. He’s the garden designer who generated rare garden-related headlines when his ‘Australian Garden’ won Best in Show at the Chelsea Flower Show in 2013. One of the surprising and inspiring elements of that garden was its billabong. Here is it in case you’ve forgotten:
Bush-inspired swimming holes of naturally cleaned water, where tadpoles cavort and dragonflies skim while we swim, are a Johnson speciality. And having drooled over his new book, Connected (Murdoch $60), a billabong is now on my list of highly desired.
A natural swimming pool is something of a revolutionary idea in Australia. We love our pools, but even those that defy the shiny-tiled turquoise traditions use non-natural systems for cleaning the water – chlorine, salt and ozone in various combinations. Yet the technology of naturally-cleaned pools is decades old and constantly evolving. There are some 20,000 private and public natural pools in Europe. Germany has built more than 100 public swimming ponds in the last few decades, each designed to cater for thousands of swimmers a day. These swimmers aren’t waking up with ear infections or worse, so how does a naturally cleaned pond work?
“There’s a filtration zone within the body of the pool, or in a little alcove built into the pool,” explains Johnson. “This zone mimics the natural system. In an alpine stream for instance, the water runs over pebbles and the enormous surface area of those little pebbles allows for large populations of microorganisms to live. They remove the nutrients from the water, keeping it clean. The same thing happens in the filtration zone of a built billabong. Microorganisms clean the water, which is constantly moving through the filtration zone.”
The constant movement of the water means there are no mosquitoes. But there is maintenance. Like a bush garden, a bush pool is not a set-and-forget option. “How much maintenance you do depends on how you want your water to look,” says Johnson. “I skim the leaves, and brush the biofilm that grows on the rocks.” The biofilm is growing medium for more cleansing microorganisms and isn’t a problem, though it can feel a bit slimy.
This is Johnson’s swimming hole on his steep bush property in Olinda, in the Dandenongs outside Melbourne. It incorporates a shallow beachy area, with flat rocks overhung by tree ferns “perfect for sitting under with a gin and tonic”, as well as a deeper area for jumping off a rock ledge into, and a waterfall for standing under. He’s designed swimming holes for many of his clients too, the stories of which are outlined in Connected . As these designs make clear, the billabongs are part of an integrated water management system, whose complexity depends on the size of the property and the requirements of its water resources. While the water engineering impresses, the real allure is the notion of an idyllic bush waterhole, in our own backyard.
Photo of Olinda is by Claire Takacs from the book ‘Connected: the sustainable landscapes of Philip Johnson’, published by Murdoch, $60, and the photo of the Chelsea winning garden is from the Ross Garden Tours blog.