Collecting Rainwater in the City (and maybe even drinking it)

| Gardening, Urban Permaculture, Water Harvesting + Reuse | comments | Author :

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If you’ve been hanging out in many of Australia’s cities this last week or two, you may have noticed a lot of rain about.

Falling off roofs, gushing down gutters and along stormwater drains, those droplets that sound so glorious on a tin roof are often a lost resource in cities, washing down our hard surfaces and heading out to sea.

Yet there’s the opportunity to capture and store so much of that rainwater in our cities and put it to good use, in our gardens and our homes. In fact it’s rather crazy not to.

After all it’s free, untreated and saves that precious resource being washed down our stormwater drains along with street pollution that eventually ends up in our waterways.

And given that we can expect more water stress in communities in years to come, getting your home set up is a good and darn sensible idea.

There’s been a long-held kneejerk reaction in the past against harvesting water in cities due to pollution concerns, but with careful management and systems built with this in consideration, it’s an easy hurdle to overcome.

As a result many councils around Australian cities are now actively encouraging the installation of rainwater tanks in new and existing homes, with many providing rebates for installation, and some making it a requirement on all new homes.

Last year the Australian Bureau of Statistics said that just over 2.3 million households in Australia used a rainwater tank for their water source – more than a quarter of households, an increase from 19 percent in 2007.

However in cities, where water is readily available for buying and piping directly into the home, mains water remains the most common option.

The type of system you can get in your home depends on circumstance, what you want to use the water captured for, and of course, space available.

Do you want to capture water simply to water your veggie patch every other day? To use in your laundry and bathroom? Or do you fancy going whole hog and using captured rainwater for everything in your home, including drinking water?

Capture for your garden can be as simple as a small or slim tank with a hose attachment or a tap to fill your watering can.

If your garden’s needs exceed that, or if you’re looking to hook yourself up to something larger that will cover off your laundry and bathroom needs, something like a rainbank with a tank system is great for controlling water supply, by automatically selecting the water source from either mains or harvested rainwater.

Want to provide rainwater for every facet of your urban home and lifestyle? It can be done.

Yes, despite any preconceptions, you can actually capture water in cities to use for drinking water. One man in particular (who you may have heard of) Michael Mobbs has been doing it successfully for decades.

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Mobbs, who set his inner city Sydney home up with tanks to harvest rainwater from his roof in 1996, has since been testing the water harvested and found it to be cleaner than the mains water provided in the city.

Mobbs has continued to measure his rainwater consistently over the years.

First testing in 1997 showed that faecal coliform bacteria levels were consistently zero except in the water sampled in June 1997 when the solar panels on the roof were cleaned, potentially causing some disturbance, while turbidity levels (suspended matter in the water) measured well below guidelines too.

Metals in the water when compared to mains water showed much lower levels of arsenic and mercury, and comparable levels of lead.

In his book, Sustainable House, which details his entire experience of setting up a tank, harvesting, testing and using the water, Mobbs says his family overcame the fear of architects, builders bureaucrats, plumbers and the like by researching the facts themselves.

“The water tastes delicious; fresh, sweet and cool from my buried tank, without the chlorine smell or its polluting and harmful by-products,” says Mobbs in his book.

“Get this sweet nectar, taste it, see how ordinary it is, and you’ll wonder at the awfulness of red tape, ‘experts’ and all those who would stand in the way of the citizen drinking it. Killjoys abound. Overcome them.”

Mobbs system overcame any of the potential pollutants that harvesting water in the city may bring with a ‘first flush’ device, which diverts the first 6-10 L of dirty rainwater away before harvesting the following clean rainwater into the tank.

Helping keep the water clean is a sump that excludes the last of any heavy sediment, and self-cleaning gutters that exclude any droppings, leaves and debris from the gutters, but allow water to enter.

All harvested water enters a 10,000 L steel-enforced concrete tank hidden below the house’s back deck – which is generally enough for a family of two, and about all the water their tiny roof can capture.

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A very serious looking Nick, next to Michael Mobbs’ rainwater collection pipe

For any of the above uses – from watering the veggies to drinking – we recommend setting yourself up with the newer stainless steel tanks.

We looked into the options when we were researching water tank options for drinking water for our farm, and found stainless steel to be one of the best options for health and recyclability.

Our latest water tank needs have been urban, however – for supplying irrigation water to the 107 Rooftop Garden in Redfern.

Once again, though, stainless steel tanks were our preferred option – 100% recyclable, no leaching, and they’ll last for many 100’s of years unless you drive a truck over them.

So we recently installed these slimline stainless steel tanks, nearly 1800 L each, at the 107 Rooftop Garden, to harvest roof water for the irrigation of all the food plants on site.

Their slim shape make them perfect for sliding into smaller spots on the site, preventing precious space being wasted – for this reason they’re also perfect for fitting down those skinny spaces next to your house.

Their slimline shape is also perfect for getting them up a stairwell, which was essential in our case.

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So take a look at your roof and rainfall this week – is there anywhere you might be able to start harvesting that sweet free water for your home and garden?

Further reading

We cover the design + implementation of rainwater collection and use for resilience in both city + country extensively in our Permaculture Design Courses. Where there is water, there is life.

A humungous THANK YOU to Select Water Tanks for their very generous contribution to the 107 Rooftop Garden.

Are you collecting + using rainwater in the city or the suburbs? What do you use it for? We’d love to hear…

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Article by Emma Bowen – grower, writer and thinker – find her over at The Slowpoke

See the comments

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Comments

25 responses to “Collecting Rainwater in the City (and maybe even drinking it)

  1. I am familiar with Michael Mobbs’s research and it prompted us to install ranwater tanks years ago in our Denistone house. So far we have 10,000 L capacity tanks for water running from the roof of the house and further 5,000 in tanks collecting water from garden sheds (the latter used only for watering the garden).

    We drink and cook with rainwater, but boil it before drinking, as we do not have filters. After years of doing so we are still alive 🙂 and the water tastes much better than the one running from our city taps.

    1. Fascinating! I collect more than enough rainwater for my small urban garden in a dual water butt system off my + my neighbours roof, so would love to drink it too as am really concerned with everything in drinking water. Does boiling it clear all the contaminants (heavy metals/OVCs etc)? Seems so simple!

      1. It depends where you are as to the quality of the water, and there’s lots of factors like what the roof is made from, is there a heavy bird poop loading if you’re under a big tree, etc etc – boiling the water will not clear it of heavy metals – we suggest you get some tested (easy to do) before throwing yourself into it, but make sure you send in a sample of your tap water at the same time! you might be surprised 🙂

  2. I would love to get a rainwater tank and often think of it.
    I just wish it made more financial sense, though I probably shouldn’t consider that.
    One Kilolitre of Sydney mains water cost me $2.45
    Just running and maintaining a rainwater pump would cost more than that.
    And now there is no installation rebate for me in Sydney NSW.
    So the cost of a new tank would be more than a lifetime of mains water usage cost, for me.

    1. Yep good point, if we’re talking in purely economic terms, right now mains water is much, much cheaper for the end user. However, there are other factors like resilience, and choosing to not outsource your impact, that could be considered.

      Also, installing some pickle barrels to catch water from your downpipe and adding a basic hose or tap to their base is a DIY option, which costs very little and will increase your home’s water security in dry times, which we have seen in the past and will surely see again.

      1. Good idea, I will search around for some used drums or IBC tanks, as a first step for the garden.
        I would much prefer to be drinking water without fluoride added also.

    2. We are rural and collect every drop we can. We filter it before drinking, tastes great.

      @Jeff – not sure what your daily consumption is, but we are VERY conservative) as our roof area is small) and it’s about 120l (excl laundry which we do in town once a week) per day. This is for 2 people. A kilolitre = 1000l, which I would guess would last city people 1 week at a minimum? This is 2.45 * 52 = $127.40 per year. Not sure if there are other base fees on top of this? A 22,000l tank just cost us $2450. If I divide that by $127.40 that gives 19.2 years. These tanks should last more quite a bit more than this as they have a 20 year guarantee! A pressure switch pump is not so expensive, a few hundred dollars or so, so I am sure it makes financial sense over the long term. Of course, no flouride, chlorine, and other contaminants that will cost your health over the long term (difficult to measure their cost). Inevitably the price of piped water will never go down.. and the quality will decrease as waterways and watersheds are more polluted over time. Some councils are adding treated sewage to the drinking supply as well. The cost to the environment is much higher than buying a tank that will last more than 2 decades. One limitation may be the water company’s reluctance to allow you to disconnect from their supply – this problem is worth fighting against (from a free choice as well as a sustainable point of view).

  3. I think the lac of support from builders etc in the past was more to do with the fact that there is no money in people supplying their own water. 🙁
    We have the slab in place for our tank. We’re getting in a 29,000 stainless steel tank, hopefully in the next month or so. Our chooks get their water off their shed roof that fills a 1000L slab tank, the greenhouse has 4 tanks attached gathering up to 1800L, the shed funnels its water into our original 3000L poly tank and even the water from the cubby roof is in the process of running into tubes that go into some small 200L tanks in the veggie patch that allow me to turn on their taps and drip irrigate the garden beds. I love water catchement and having my own supply, free from chlorine and fluoride. I can’t wait to get the big tank in place. 🙂

  4. I installed rainwater harvesting at my (NZ) urban block last year; I urgently needed to buffer the stormwater which was discharging onto the ground and flooding my clay flat (thanks to previous owner’s stormwater disposal choices). Lots went wrong. I had to do massive research and consultation to fix the mess the first tradie made. I ended up writing a couple of articles for Organic NZ magazine which are online. Part 1 is the basics: http://www.organicnz.org.nz/node/987
    Part 2 gets into drinking tank water: the safety of it, what you should add to a basic system http://www.organicnz.org.nz/node/988
    The sidebar recounts my own tale of woe! I hope other people can learn from what went wrong at my place, so they don’t have to find out the hard way. I had very knowledgeable Australian sources say the same thing about Australian tradespeople’s lack of knowledge about rainwater harvesting. Get personal recommendations before settling on someone.
    Full respect to Michael Mobbs and I’d love to drink the tank water at his place. It’s great that he has done ongoing testing to refute the scaremongering. But I can’t see that a first flush diverter that size is doing anything useful.
    Love Jessie’s comment about all the tanks going in at their place. Nice one. I could only fit a 5700 litre tank in but there has to be a phase 2: a big arse tank down the bottom I can manually fill from the top tank. Been so dry here this summer I could think I’m back in Australia …

  5. Great to hear about urban sky juice harvesting in Oz. I’m on tanks on the Otgao Peninsula South Island Nz and have huge gums behind my house which as much as I love them (originally from Oz) they fill my gutters up in no time with not only the elaves but teh tiny nuts too. I’m intriged by the self cleaning gutters taht Michael Mobbs has. Any where I could find out about them?

  6. I use a Team Poly Modular (750 litre) Drink Water Tank for cooking, drinking and home brew beer. It strains, captures 40 litres of run off and settles the water in the first tank. A filter is placed between the first tank and the two 250 litre storage tanks.
    In use for 8 years with no water quality problems.
    A 6500 litre tank is used for garden watering.

  7. We now have our second water tank. First is attached to our carport roof – garden use only.
    Second tank to our new large shed down the back of our suburban property.
    Problem:
    The roof catchment area is partially under a large Casuarina (in a neighbours yard ) and the stored water when used smells like sulphur – yukky. The filtration of the gutters is done manually by my husband every month – we do have gutter guards and downpipe guards, but the she-oak has such a lot of needles and nuts drop.
    Does anyone know :
    1. does it harm veges if used straight from the tank?
    2. Is there any way of changing the smell?
    Thanks for such wonderful articles always. Nicci .

    1. I would say your veggies would be absolutely fine, it sounds like you just have decomposing leaf material in the tank (and maybe some other bits)

      To change the smell you’d need to clean the tank out first off (yay) but short of adding minerals or chemicals to the tank, over time you might end up in the same situation. Great to have that garden water supply sorted though! Yay you 🙂

  8. In ancient cities, they dug big pits and sloped the sidewalks in one area of the neighborhood. The rainwater would collect in the pits (lined with pebbles) and they called it a well.

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