‘Keep rain where it falls’: Michael Mobbs, the ‘Off the Grid Guy’

After Council connected Quaama to the Brogo Dam supply in 1984, they sent a truck through the village collecting everyone’s rainwater tanks. ‘You won’t be needing these anymore—let us do you a favour and remove them for you!’ They needed people to pay for household water now—the last thing they wanted was people collecting their own.

But by the time we built our new house in 2008, the NSW Government was offering rebates for every new tank connected to toilets or washing machines. And development approval relied on such environmental features too.

Many Quaama residents collect rainwater from their roofs now. For those who don’t, their share soaks into their garden, or runs off into the channels that Council digs along the roadsides, breeding mosquitoes and frogs until it seeps into the ground or evaporates. But at least the rain ‘stays where it falls’—one of the main tenets of Michael Mobbs’s presentation to the Bermagui Institute in February. Mobbs, the ‘Off the Grid Guy‘, has disconnected his inner-Sydney home from mains water and sewer (and electricity) and promotes sustainable living.

By re-using his treated sewage to flush the toilets, wash clothes and water the garden, Mobbs has kept over two million litres of sewage on site and out of the ocean. There’s a model of Mobbs’s ‘Sustainable House’ in the Powerhouse Museum (pictured above).

But back to our towns. Bermagui has had mains water since 1955 (originally sourced from Couria Creek and Tilba Dam) and Cobargo since 1958 (originally from Illawambra Weir). These days, both towns are supplied from Brogo Dam.

Mobbs calculated that, in Bermagui, about 948,000 litres of rainwater falls on the Lamont Street road surface between Wallaga and Montague streets every year. And, ‘Bermagui village is about three square kilometres,’ he says. ‘Twice as much rain falls on Bermagui, and is sent out to the ocean, as is used from the mains water supply.’ Levels in Brogo Dam had fallen to 12% capacity at the time of the recent fires.

In 2018 Council installed 600 metres of kerb and gutter between Keating Drive and George Street on Wallaga Lake Road to ‘formalise stormwater management’ in the area. Chris Best, BVSC’s Manager of Water and Sewerage Services, says, ‘Stormwater typically runs to a creek or the ocean, often via sediment-control structures, gross pollutant traps and sometimes rain-garden style vegetation beds to clean up any pollutants as much as possible before going to the environment.’

Writing this, I thought about the language. When a council offers to manage ‘stormwater’ it sounds helpful. But if they wanted to manage your ‘rainwater’, would you be as grateful?

Rather than ask Council to dismantle their ‘stormwater’ infrastructure, for homeowners Mobbs recommends ‘leaky’ pipes, known around here as ‘ag’ pipes. A length of ag pipe can be used to replace the same length of drainage pipe. There’s a three-minute instructive video on Mobbs’s website. In his council area, ratepayers are replacing regular pipes with ‘leaky’ pipes on the road verge, with no apparent blowback from the authorities. Then they’re planting productive, edible gardens there. A thermal image of his suburb shows that roads planted like this are two to four degrees cooler at night.

Mobbs’s premise is that if Bermagui’s rainwater was kept where it fell, the town would be a lot cooler. Residents would save money on power bills. ‘And cooler streets increase business for main street shops. On hot days, they lose business to shopping centres because customers flock there for the air con.’ Research, data and tips to cool house, streets, towns and cities are on the Street Coolers website.

The other side of the equation is ‘waste’ water.

Quaama is not sewered and most houses have a septic tank. When I bought my old cottage in 1997 it had no septic at all—the previous owner had connected the kitchen sink and bathtub to lengths of 50mm polypipe which she moved around the garden according to need. And there was no inside toilet. But I was a city girl and drew the line at traipsing up the garden path to the long-drop on winter nights. And an internal flushing toilet required proper waste disposal.

Quaama soil is very high in clay, and septic tanks often overflow after rain, so my plumber recommended an independent, onsite, ‘aerated water treatment system’ (AWTS). It takes all the household waste, grey and black, treats it and pumps safe, clean water back onto the garden through a series of sprinklers.

The AWTS was expensive but I’ve never regretted it, especially during the millennial drought when mains-water sprinklers were banned. Passers-by would glance accusingly at my sprinklers, showering away. I was about to put a sign on the gate, ‘Sprinklers are connected to RECYCLED WATER from my BIOSEPTIC’, when the drought ended and restrictions were lifted.

In 2020, everyone in Quaama still deals with their own sewage, in one way or another (and for our trouble we each pay Council an annual $110 ‘onsite sewage management fee’).

It’s different in Cobargo. In 2008 Council connected every dwelling to the sewer. The effluent is pumped to the Cobargo Sewerage Treatment Plant (STP). ‘Treated water is then re-used on the showground,’ says Chris Best, ‘and the remainder—treated water not needed on the Showground—is discharged to Narira Creek. Solid waste is separated and dried and then goes onto local farms as a soil enricher.’ Rates rose by about $1000 per year—in perpetuity—when the sewer went in.

Sewerage pipes were first laid in Bermagui in 1974. Sewage is treated at the Bermagui STP to the south of the town. Some treated water is used on the golf course and the remainder is pumped out to sea. Like in Cobargo, solids go to local farms.

So do we handle the water/waste cycle sensibly in these three towns?

In Quaama, the rain stays where it falls. Waste is diverted to septic systems that are pumped out when needed—solids go to wherever the carter chooses to take them. Septic tankers are received at Merimbula STP, where the sludge is treated, and solids then go to local farms. Council is installing a new septic sludge facility at Bermagui STP to reduce cartage costs.

In Cobargo too, rain stays where it falls. Waste, including grey water, goes to the Treatment Plant; solids go to local farms, treated water onto the Showground or into the creek. All good.

Now to Bermagui. Grey and black waste is treated and liquids and solids diverted to where they are useful. All good. And rain? Many residents collect rainwater from roofs but rain that falls on hard surfaces like roads is redirected to waterways and the ocean.

According to Michael Mobbs, if that water was kept where it fell, it could result in a cooler Bermagui—good for power bills, good for business.

 

Thanks to Chris Best and David Rodgers from BVSC Water and Sewerage Services for help with historical and technical data.