In ‘Greywater’ Category

ReNew Editor, Robyn Deed

ReNew 135 editorial: Water inside and out

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In Sophie Thomson’s Adelaide Hills garden, indigenous plants that survived under a ‘no watering’ scheme for several years have struggled this year, with some dying. In Victoria, we’re seeing reservoir levels dropping, street trees struggling and many gardeners dismayed over just how dry the soil is. It’s a similar story in many parts of Australia, with the tinder-dry bush causing devastating fires such as those in the Tassie wilderness.

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If we don’t want to abandon our gardens, critical as they are in providing shelter, cooling and habitat, as well as food, what do we do? In this issue, we explore some of the approaches that can help gardens thrive with efficient and effective use of water.

Sophie Thomson issues a challenge to rethink our gardens into watering zones, with most of the garden given to ‘no water’ and ‘low water’ plants — think local indigenous planting and choosing plants appropriate to the site and conditions. But that doesn’t mean abandoning the higher water usage plants altogether, such as vegies; instead, we look at more efficient ways to water, including drip irrigation — potentially regulated according to temperature and rainfall — and wicking beds, where the water is delivered to the plant roots and wicks up to where it’s needed. We’ve previously covered rainwater and greywater use in detail (see ReNew 125 and 130) so this time we shift attention to using stormwater via rain gardens, a way to reduce polluted runoff into our rivers and water the vegies at the same time. We also visit Melliodora, the Australian permaculture co-founder’s property in Victoria, and find out how permaculture principles meld with water efficiency.

In the tropics and subtropics, the problem is slightly different — coping with deluges in summer and relatively dry winters. Two northern Australian gardening experts give advice on what to plant and ways to use water effectively in these regions.

It’s not all about gardens. We also look at where households can save water, inside and out, and compare water usage around Australia. Our mini guide is on waterless toilets, definitely worth considering as a water- and pollution-saving measure.

Our main buyers guide is on heating. We often get queries about hydronic heating, so we’ve updated our guide to include both reverse-cycle air conditioners and hydronic.

And amidst all the talk about batteries and going off-grid, we take a look at what’s available in all-in-one battery systems, and where the market is heading. We also examine the sustainability benefits of solar and solar + battery systems. If you’ve ever wondered just how much effect your solar system can have on the grid—can it really affect the output of a coal-fired power station?—this article is for you.

Plus there’s lots more: a DIY on double glazing, a mini hydronic system, reviews of 10 water-saving books, where wind farms are heading and the Pears Report on how different the approaches to energy policy can be.

As we head into a disturbingly hot start to autumn, an election year and post the Paris climate talks, we welcome your feedback and input. We hope this year we can see action on climate change rather than just words.

Robyn Deed
ReNew Editor

 

ATA CEO’s Report

The year 2015 ended with an historic agreement at the United Nations Climate Change Conference in Paris to limit global warming below 2°C. As a signatory to the agreement, Australia is now part of the push for a net zero emissions world.

At the ATA we are at the forefront of advocating for, encouraging and advising on sustainable technology and practices in Australian homes and communities to make a big impact on reducing carbon emissions. We are continuously researching and investigating new and emerging technology for a more sustainable future.

As an example of putting knowledge into action, we were very excited to team up with the Centre for Appropriate Technology (CAT) to install an off-grid solar system at the Oriners ranger base in far north Queensland. We have been admirers of CAT’s work installing solar systems in remote Indigenous communities for many years and have profiled some of their work in ReNew previously. After funding cuts to their Bushlight program, the ATA was more than happy to work with CAT to trial a project reducing the costs of installing a system, with ATA members volunteering skills and labour.

A big thankyou to David Tolliday, John Dickie, Olivia Laskowski and CAT’s Andre Grant for their work and dedication on a successful first project. We look forward to collaborating again in our goal for a net zero-emissions world.

Donna Luckman
CEO, ATA

You can purchase ReNew 135 from the ATA webshop.

stormwater

World-leading technology: Water harvest

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Smart design is leading the way in solving the problem of water shortages and pollution in our impermeable cityscapes. By Robyn Deed.

Tucked away in the back streets of East Melbourne is a world-leading project, patent pending. There’s not much to see—there’s a nature strip planted with wetland grasses in the middle of Darling Street, and an intriguing-looking steelwork shed in the park across the road. If you peered into the shed, you might see a poster that describes what’s going on. But most likely you’d walk on by, perhaps remarking that the grasses are thriving or the trees in the park look healthy. Which is exactly what’s intended.
What’s hidden beneath the bed of grasses is an innovative system for stormwater treatment and harvesting. With four years of research behind it, this City of Melbourne initiative uses existing technologies—water storage tanks, a natural biofiltration ‘rain garden’ and filters—but combines them in a smart way . The result is a system that’s more robust than other systems, takes up a tenth of the space and costs less to both install and maintain.

The problem

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The system aims to solve two problems: contaminated stormwater flowing into our waterways and the shortage of water for irrigation in our warming climate.

Contaminated stormwater is a major problem in our impermeable cityscapes. In a natural landscape about 15% of rainwater runs off into waterways, with the remaining 85% soaking into the soil. In a built-up area that gets flipped: about 85% is now entering our waterways.

Ralf Pfleiderer from the City of Melbourne says it’s getting worse. “We’re improving our road surfaces but making them less permeable in the process, concreting over the bluestone gutters and replacing asphalt with bluestone over concrete,” he says.
The water running off the streets into nearby rivers is contaminated by lots of things: by ‘gross pollutants’ (larger things such as plastic bags, other litter and leaves); by silts and sands washed out of the soil; and by oils from cars contributing toxic heavy metals.

The extent of water runoff into our waterways, combined with the extended drought and water restrictions, means that water for irrigation is at a premium. Many of our urban trees are struggling. Even after a recent year of good rain, soil moisture levels haven’t returned to normal. So, as well as treating the water to remove pollutants, this project provides a source of water that can be harvested for irrigation.

The solution

Central to the system is the separation of stormwater capture from treatment. Other gravity-feed systems use rain gardens for both capture and treatment: the water from road gutters runs directly, by gravity, into the rain garden as it rains. This means the rain garden has to be below the level of the road—a design and safety issue in an urban streetscape (imagine a garden bed below the level of the road). In addition, the rain garden has to be much larger to enable it to capture and treat all the stormwater as it’s flowing.

What the Darling Street system does instead is to first capture the stormwater into a large (300 kL) underground tank, which allows the water to be slowly filtered through the garden bed after the rain event has passed. Using this approach, the system is able to treat the water from a 37 hectare catchment area—this would normally require 1200 m2 of rain garden, but this system needs just 120 m2 to do the same job. In addition, it’s able to supply 21 million litres of water annually (or 18 Olympic swimming pools) for irrigation.

Rain garden as filter

The rain garden itself is a natural biofiltration system, made of sand and grasses. Most of the filtering is performed by the bacteria coating the sand particles and plant roots—a natural biofilm, not by added bacteria. The plant stems help to break the surface tension and so maintain the flow of water through the filtering sand. They look great, too. Brendan Condon from Biofilta, one of the companies involved in the system’s research and design, says that the plants in the Darling Street rain garden are already fully mature whereas ones planted at the same time in a typical gravity-feed rain garden would still be establishing.

The system has been robustly designed to avoid many of the problems that plague other rain garden systems. Although rain gardens are good at filtering out contaminants, they get clogged by litter, sediment and silts, requiring expensive manual maintenance. To avoid this issue, before capturing the water into the holding tank, there are two filters applied to the water—a gross pollutant trap, to remove leaves and litter, and a sedimentation chamber, to settle out a lot of the silts. Both these filters fill up too, of course, but they’re easier to maintain as they can be vacuumed clean mechanically, rather than manually.

The cleaned water is either stored in a reuse tank (also beneath the ground) for irrigation use, or returned to the stormwater drains as cleaned stormwater—much better for our waterways than the original polluted stormwater. The final step is a UV filter to ensure that any residual bacteria are killed.

Harvesting the water

Come summer, the system will switch to using water from the reuse tank for irrigation as needed. Irrigation could also be applied in winter, but Ralf Pfleiderer says that this is something for down the track. In winter the water needs to be applied below the surface as the surface layer is often already wet, leading to run off. But irrigation is still needed in winter: beneath the surface the soil moisture remains low, after so many years of drought.

Unlike gravity-feed systems, this system does require electricity to pump the water through the rain garden for filtering. But Ralf notes the pumps run just two hours out of 24, under low load, with a total electricity cost of about $200/year, offset using carbon credits.

Future water supply?

The most significant current application is to clean stormwater, thus reducing pollution in our waterways. When used for irrigation, such systems can also help keep parks and street plantings healthy, and so help alleviate the heat island effect in cities as our climate warms. Brendan Condon notes that he’s been involved with installing similar systems for apartments to provide irrigation for their gardens.

Looking further ahead, Ralf speculates that such systems could become part of a decentralised water storage approach. We could be using harvested stormwater on our gardens, and in our toilets and washing machines, while our reservoirs are used purely for drinking water.

Stormwater could even cover all our water needs. Melbourne currently uses 400 GL of water a year, compared to available stormwater of about 463 GL. We only use around 10 GL of that at the moment, so at the very least stormwater could be a much bigger part of our future water supply.

If we can switch to thinking of reservoirs as just one part of our storage system, rather than the full system—as super-sized rainwater tanks in effect—maybe we can start to reduce our dependence on them.

The system was researched and developed by Biofilta and Cardno, in conjunction with the City of Melbourne. A patent for the BiofiltaTM bioretention system has been applied for.

More info:

www.melbourne.vic.gov.au/ParksandActivities/Parks

www.biofilta.com.au

130_greywater_guide

Greywater system buyers guide

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Although many regions no longer have water restrictions, water is still a very precious resource in a country as dry as Australia. Greywater systems let you use water at least twice, which makes good environmental sense. Here, we look at what systems are available.

The advantage of greywater is that we produce it on a daily basis. In many cases it can be diverted to the garden with minimal effort and cost in a number of different ways. You can opt for a low-cost DIY system using something as simple as a greywater diversion hose attached to your washing machine outlet. Or you might be considering installing a full commercial greywater system. Whichever way you go, there are a number of things you need to consider.

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This guide highlights the main issues associated with greywater reuse. There are many choices available and there is no single solution for all circumstances. Therefore, the more research you do, the more suitable your system will be for your particular situation.
There can be many restrictions as to where systems can be installed. In some cases, especially for retrofits, installing a greywater system will require major works—this can make the system cost-prohibitive.

Greywater sources

Greywater is any wastewater generated from your laundry (sinks and appliances), bathroom (baths, showers, basins) and kitchen (sinks and dishwashers), before it has come into contact with the sewer. It does not include toilet wastewater, which is classed as blackwater.
However, while kitchen and dishwasher water is technically greywater, unless you are treating it, it is recommended that you don’t use this water source. Kitchen water only makes up around five percent of total water consumed in the average home, yet it is considered the most contaminated. This is partly due to high sodium levels from some dishwashing detergents, particularly from dishwashers, solid matter such as food waste from rinsing dishes, as well as fats, grease and oils from cooking and cleaning, which can all damage soil structure if allowed to build up.

What’s in the greywater?

The chemical and physical quality of greywater varies enormously, as greywater is essentially made up of the elements that you put into it.
Generally speaking, pathogen and bacteria content is low in most greywater sources (unless you are washing contaminated items, such as nappies) and, provided you take steps to minimise potential contact, such as using subsurface delivery of the greywater, it is of minimal concern.
Choosing the right cleaning products is perhaps one of the most important elements in reducing the risks associated with greywater reuse. The elements phosphorus and nitrogen are nutrients necessary for plant growth. If these elements are kept to a suitable level by choosing cleaning products with low phosphorus and nitrogen content, they can replace the need for fertilisers for gardens and lawns—the nutrients can actually be utilised by plants and soils.
The main concerns with greywater are salt build-up from cleaning products and increased pH levels in the soil. Both can have a detrimental effect on your soil and plants. However, they can both be mitigated by monitoring, conditioning your soils for optimum health and taking care to choose cleaning products with little or no salt.

Salt

Salt build-up in soils, particularly sodium salts, poses perhaps the greatest risk associated with untreated greywater reuse. The accumulation of salts in the soil can damage soil structure and lead to a loss of permeability, causing problems for soil and plant health. The main source of sodium is powdered washing detergents and fabric softeners that use sodium salts as bulking agents.
Concentrated powders and liquid detergents generally have fewer salts than the average powdered detergent. There are many powdered detergents on the market that now have low or no sodium content.
For more information and a list of products that are greywater friendly, go to www.greysmart.com.au (see the resources section for information on this site).

pH levels

Generally speaking, pH levels outside the optimum range of between six and seven affect the solubility of soils and hence plants’ ability to absorb essential nutrients. As most gardeners know, pH values range from one (acidic) to 14 (alkaline), with seven being neutral.
As untreated greywater is generally alkaline, if you have an acid-loving garden, you will need to consider the types of cleaning products you use—washing powders generally make greywater very alkaline, as do solid soaps, while liquid soaps tend to be more pH neutral. The pH of greywater can vary depending on the source—shower water is often fairly neutral compared to washing machine water, for instance.
Before you’ve even applied greywater, pH levels can vary from acidic to alkaline from one part of the garden to another. Given this variability and the likelihood of greywater raising the pH of your soil, it is advisable to regularly monitor the pH and condition of your soil. Acidic soils can be made more basic with calcium carbonate and basic soils can be made more acidic with sulphur. To monitor this, pH test kits and soil conditioners are available from most nurseries.

Other issues

Although salt build-up and pH are of particular concern, there are other greywater components that can have an impact on your soil and plants. They include fats and oils from soaps and shampoos, disinfectants (including eucalyptus and tea tree oil), bleaches, toothpaste, hot water and sheer volume of water—leading to over watering.
For more detailed information on greywater composition, see section 2.4 Composition of Greywater in NSW Guidelines for Greywater Reuse in Sewered, Single Household Residential Premises (www.bit.ly/NSWGreywater) and Oasis Design’s Fecal Coliform Bacteria Counts: What They Really Mean About Water Quality (www.oasisdesign.net/water/quality/coliform.htm).

The complete article looks at greywater system types, use of greywater, greywater regulations and more.

Read the full Greywater Systems Buyers Guide in ReNew 130.

Download the full table of manufacturers, suppliers and their systems.

ensuite loo web

Composting toilets in an urban setting

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Jeff Knowles had reservations about putting in a ‘long drop’ in his urban home, but was pleasantly surprised.

In 2001, my partner Chrissy and I engaged Strine Design to assist in the design of our new sustainable home in Queanbeyan. Under the leadership of architect and builder Ric Butt, Strine had been responsible for numerous buildings of a deeply sustainable nature in the Canberra area. Many of these included sustainable elements that were not available through other builders/architects at that time—composting toilets being a case in point.

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Initially, it must be said, I had reservations (mostly to do with smell and a reputation for being difficult to maintain) about putting in a ‘long drop’, but several visits to see Clivus Multrum units already installed around the district convinced me that the idea was worth proper consideration. Chrissy was especially keen, due to the water saving and general ecological advantages.

Deciding to incorporate the unit into our home design and actually getting that design through the local council turned out to be two quite separate things. Fortunately for us, our architect Ric Butt had a lot of experience in this area. He’d pioneered the use of the units with forward-thinking councils, even in water catchment areas such as the Googong Dam where it was absolutely crucial for them to work well. He also had ready access to evidence from other composting toilet owners of the minimal maintenance required.

The eventual approval only took two weeks. With written agreement on our part to maintain and service the unit, our council agreed to pass the ‘radical design’—which, in fact, represented a return to many concepts that had previously been commonplace in Australian houses in the bush.

The house was duly built and the toilets (one CM10 unit with two separate toilets) were installed. We had them installed partly raised inside and partly submerged outside with a service hatch. This is one way of installing them—it means a couple of steps inside, but not as far to descend to do the maintenance outside.

We obtained wood shavings from the local sawmill and our learning began. Ric’s flippant suggestion was to start the composting process by just throwing in a dead possum. Not surprisingly, I couldn’t find said deceased possum lying anywhere around, so we finished up using a product from the supermarket called Actizyme.

Actizyme is designed and marketed as a natural drain cleaner but is also an excellent compost starter. It took me a while to understand that the active microbes in standard food composting systems are the same as the ones in the Clivus Multrum.

That established, we settled in to using the loos—and fielding the inevitable questions from visitors such as “Where is the button?”, “Why don’t they smell?”, “How much water do you really save in a year?”

The council came out to visit a few times in the first few years to check that the neighbours were not affected by smells etc from the toilets and that we were doing the right things by the greywater. Now they occasionally send people to us who need help with the approval or maintenance processes.

Read the full article in ReNew 128.
northern_greenhouse

Earthships downunder

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In ReNew 122, Martin Freney presented his research on the performance of earthships. Here, he provides additional information on earthship design for Australian and New Zealand conditions, and planning issues.

Download the PDF here.

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Or read more on the performance of earthships in ReNew 122.

Naturum side view web

Composting toilet buyers guide

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Tired of flushing water? With care and maintenance, a composting toilet can be a good alternative to the water-loo, writes Anton Vikstrom.

Who has ever pondered what happens when you flush the loo? Apart from thoughts of how much water is chasing your deposit, what about the process downstream? There are alternatives for people to take care of their business on site. While composting toilets have been popular on rural and ‘off pipe’ locations such as national parks for years, increasingly people are interested in composting their sewage on site.

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So, what is a composting toilet? How does it work? And how can I get one? This article provides an introduction to composting toilets as well as important information about maintenance.

Sewage treatment today

While the modern sewerage system is an integrated engineered marvel, it is also a marvel of wasteful design. In a standard home in a developed city, all black (toilet) and grey (shower and sink) water is combined, usually in the house slab, before leaving site. From that point it is a long downhill trip to our modern wastewater plants. In Melbourne alone, 330,000 million litres of wastewater are processed each year, including trade waste from industry.

Our centralised sewerage system is a case of out of sight out of mind. Waste is processed at primary level—sieved, screened and mashed up. It passes through a series of ponds where oxygen is circulated to aid microbial digestion of the solids. Water from the system is discharged into oceans or streams after being treated with chlorine. As they say, ‘with pollution dilution is the solution.’ However, releasing this water can cause nutrification, blue-green algae, heavy metal concentration, let alone the negative effect large amounts of chlorine has on ecosystems. Just think how 330,000 million litres of water could be used otherwise.

The other system that operates in ‘off pipe’ conditions is the ubiquitous septic tank (septic being from the Greek ‘septikos’ meaning ‘to make putrid’.) After flushing, all solids settle in the bottom of a large concrete tank and are later pumped out by Mr Wiffy. The excess fluid is disposed of in a sub-surface disposal/leach field. These systems are anaerobic and produce a classic stinky sewage smell. There is no separation of cured waste and fresh waste, allowing direct transfer of any pathogens to the leachate field. While very common in Australia, septic systems are increasingly linked to a number of water pollution issues resulting from a high density of the systems in close proximity to water catchments.

Composting toilets operate on completely different principles from conventional wet systems and offer a proven alternative.

Read the full article in ReNew 104
Ecocare

Greywater system buyers guide

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Water restrictions require creative solutions to keep gardens alive. Adam Maxey looks at the pros and cons of greywater recycling.

The advantage of greywater is that we produce it on a daily basis. In most cases it can be intercepted and diverted to the garden with minimal effort and cost in a number of different ways. However, whether you intend to buy a commercial greywater system or set-up your own DIY system there are a number of things you need to consider. This guide highlights the main issues associated with greywater reuse. There are many choices available and there is no single solution for all circumstances. Therefore, the more research you do, the more suitable your system will be for your particular situation.

READ MORE »

Greywater sources

Greywater is any wastewater generated from your laundry, bathroom and kitchen, before it has come into contact with the sewer. This includes bathroom (bath, shower and basin), laundry, kitchen and appliance discharge. It does not include toilet wastewater, which is classed as blackwater.

However, while kitchen and dishwasher water is technically greywater, unless you are treating kitchen greywater it is recommended that this source of water not be used. Kitchen water only makes up around five percent of total water consumed in the average home, yet it is considered the most contaminated. This is largely due to high sodium levels from dishwashing detergents, particularly from dishwashers, as well as fats, grease and oils from cooking and cleaning, which can all damage soil structure if allowed to build up.

Cleaning products

Choosing the right cleaning products is perhaps one of the most important elements in reducing the risks associated with greywater reuse. The chemical and physical quality of greywater varies enormously, as greywater is essentially made up of the elements that you put into it.

Generally speaking pathogen and bacteria content is low in most greywater sources (unless you are washing contaminated items such as nappies, soiled clothes etc) and as long as you take all the right steps to minimise potential contact, such as delivering greywater subsurface, it is of minimal concern.

Equally, phosphorus and nitrogen are nutrients necessary for plant growth. If phosphorus and nitrogen are kept to an optimum level by choosing cleaning products with low phosphorus and nitrogen, they can replace the need for fertilisers for gardens and lawns, and the nutrients can actually be utilised by plants and soils.

Read the full article in ReNew 102
_8175070

Stay smart with the grey stuff

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As we head into summer water is worth saving more than ever. Anjali Brown surveyed Alternative Technology Association members about their own domestic greywater systems. Here’s what you need to know.

The average house produces around 83,000 litres of greywater a year. Some Australian households have found ways to reuse this otherwise wasted resource, either with DIY nous or commercially available greywater systems. With commercial systems growing in popularity, the time was right for the Alternative Technology Association (ATA) to survey its members about their own experience with these systems.

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ATA members who had purchased a manufactured, commercially available greywater system were invited to complete the survey in May.

Of those surveyed, 80% had bought diversion systems most of which came with some form of filtration device (to remove particles such as hair and lint), a mains diverter, a surge tank and in some cases a pump. These elements differentiate these diversion systems from a simple hose out the laundry window or a good old-fashioned bucket. While untreated greywater from these diversion systems can be used to flush toilets, it is most commonly used for garden irrigation.

The remaining 20% of respondents had purchased treatment systems which involve a high level treatment of greywater via biological or chemical processes (sometimes both). The treated greywater can be stored for more than 24 hours without becoming a health hazard and it can be used for non-potable indoor water needs as well as on the garden.

Read the full article in ReNew 109.
Soap bar

Soaps, shampoos and soil

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Hard soap is out and bodywash is in when it comes to greywater in the garden. A report about the impact of bathroom products on soil shows why.

Greywater use has become so widespread in many parts of Australia that it is now more a case of who isn’t using greywater to keep their gardens alive. This is great news for water conservation efforts. Greywater use is not an exact science, though, and successful greywater irrigation depends on a number of factors including soil type, plant type and ultimately which chemicals and elements make up your greywater.

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Typically, laundry and bathroom water are the most common and safest waste waters to use depending on which products you are using. Thanks to Robert Patterson of Lanfax Laboratories (www.lanfaxlabs.com.au) and his independent study of laundry detergents we have a better idea of which laundry products are safe for greywater irrigation (see report in ReNew 98). This data has been a valuable resource over the years for people using laundry water to irrigate their gardens, yet there has been a need for similar studies for bathroom products.

With this in mind, the Alternative Technology Association, in conjunction with Associate Professor Barry Meehan and RMIT University’s Environmental Science Department, set about filling this information gap. The plan was to analyse typical ingredients in a number of bathroom products and assess the potential impact on soils.

The Alternative Technology Association (ATA) conducted a member survey last year about the types of bathroom products used in households.

The survey identified the most popular products in four categories: shampoos, conditioners, solid soaps and bodywashes. Within these categories a further distinction was made according to whether the product was mainstream, generic or ‘eco friendly’.

All of the 44 products tested in this study were brands identified by ATA members who were watering their gardens with bathroom greywater. Product samples used in this study were provided by the ATA.

Read the full article in ReNew 107.
gareden

Staying green with greywater

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Jacinta Cleary visits one experienced green thumb who keeps her garden thriving with greywater.

On a rainy Melbourne day a visit to Karen Sutherland’s edible garden is a bit like a trip to the tropics, with feijoa, mango and avocado trees all surviving well. Admittedly, the mango tree is far from fruiting, but maybe one day if the weather continues to warm.

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It’s a combination of rainwater, greywater and a little bit of mains water than keeps this suburban garden absolutely thriving. Keeping a garden alive in dry periods is one thing, but taking it to the next step and growing healthy produce with minimal water requires some planning.

Household greywater is used every day in this garden and has made a big difference. Karen specialises in designing and installing edible gardens and importantly, helping people learn how to grow and maintain their own veggies, fruit and herbs. Her philosophy on gardening is very much tied in with sustainability and the fact that sourcing food locally can help the planet by reducing transport emissions. Through years of experimentation she can judge just how much water is needed for an abundant crop of fruit and veg.

Karen and partner John had enough hands-on expertise to design and construct their own greywater system. Greywater can’t be stored longer than 24 hours, so the system is only big enough to hold a day’s worth of water. The header tank holds between 180 and 200 litres, with an overflow going to the sewerage system. Karen keeps track of how much water has gone into the header tank each day to ensure a minimum of wastage from overflow.

Read the full article in ReNew 110.