Stormwater – reducing water demand and rainwater reuse
Reducing your home’s water demand
Australia is the driest inhabited continent in the world, and as such, water is an increasingly precious resource. Water prices reflect this, and bills can soar if you aren’t careful about your water usage. Increased demand for water also requires the construction or new dams, desalination plants, and other public infrastructure at immense cost to both the taxpayer and the environment.
Luckily, there are many simple and easy ways in which you can reduce your mains water consumption.
Through the harvesting of rainwater and the recycling of grey water, it is possible for a home to become self-sufficient in terms of water use, with costs relating to installation and maintenance recouped within a year.
Six simple steps for reducing your mains water consumption
1. Choose water efficient fixtures and appliances to reduce your indoor water use. Newer shower heads, toilets, and taps are often significantly more water efficient than older models. The same goes for dishwashers and washing machines.
2. Minimise your outdoor water consumption by filling your garden with plans that are well-suited to local growing conditions. Here in Australia, indigenous plants are the best choice, as they naturally require less water than introduced varieties.
3. Reduce paved areas around your home, as paved surfaces increase stormwater runoff and heat radiation.
4. Wash bikes, cars, and other large items on lawns so that the water is used to water the lawn at the same time.
5. Avoid hosing down pavement or paths. Sweep them instead.
6. Reuse water where you can, such as by installing a grey water irrigation system.
In terms of total water used to maintain gardens here in Australia, government estimates put a figure of 90% on the amount of water used to maintain lawns (yourhome.gov). With this in mind, reducing your lawn area is perhaps the easiest way in which you can save on outdoor water use.
Instead of having an area covered with grass, try installing a garden bed, pebbles/sand, or water-hardy ground covering plants.
Reducing water use on lawns
Different varieties of grass require different amounts of water to survive. If you are landscaping your home, choose a variety of grass which is water-hardy, such as couch or buffalo grass. You will also be able to find region specific blends or species at your local plant nursery which will be well-suited to that area’s growing conditions.
Rainwater, consisting of water that falls as part of common weather events such as showers and storms, has been collected for domestic use in Australian households since colonial times.
Different locations offer different opportunities for rainwater collection and reuse. For example, urban households here in Melbourne are connected to the treated, reticulated mains water supply which comes from a central water source for your municipal area. In regional areas, homes may be connected to ‘town water’, which is another way of saying the mains water supply.
Rural households may need to source their own water, from dams, rivers, or boreholes. Whatever the location, collecting rainwater can significantly lower a home’s reliance on other water sources. Rainwater here in Australia is often of superior quality for household use than mains water.
The benefits of reusing rainwater
Using rainwater will assist urban and regional homeowners to reduce their water bills by giving them an alternative water supply to local mains. Depending on the size of the tank, the type of climate, and usage patterns, mains water use can be reduced by as much as 100% in some homes that have installed rainwater harvesting systems.
In addition to these benefits, which manifest on the micro scale, there are many larger social and environmental benefits to rainwater reuse, such as:
• Reduced need for new desalination plants and/or dams in response to drought or population changes
• Reduced infrastructure and operating costs for those who are no longer wholly reliant on municipal water supplies
• Reduced impact on natural environmental flows in rivers and watercourses.
Installing a rainwater harvesting system in your home can also reduce the impact of stormwater runoff, which reduces the risk of localised flooding and protects the environment.
The up-front purchase and installation cost of a rainwater harvesting system differs significantly depending on the type and size of tank, whether or not a pump is required, and any additional plumbing required to accommodate the new system.
Some state governments offer rebates on the cost of installing a rainwater reuse system, though these are subject to change as policies shift. You can check www.yourenergysavings.gov.au to check if you are eligible for any rebates on a new rainwater system.
How you can use rainwater
Rainwater collected in a modern, well-maintained system is suitable for all domestic or commercial applications. The more rainwater is used, the greater amount of money you will save on mains water use.
Many state government health departments recommend that homeowners use the public mains water supply for drinking and cooking, as this water is treated and usually fluoridated. However, rainwater is safe to use for these purposes and can be the best option in some areas.
Health and safety implications
There are two main ways in which the use of rainwater tanks and reuse systems can adversely impact human health:
• Indirect impact – where a rainwater tank/system provides a suitable breeding space for disease-carrying insects such as mosquitoes.
• Direct impact – Certain pathogens are sometimes present in rainwater, and these can pose a slight risk to human health in certain cases. A lack of fluoridisation can also be an adverse effect associated with using rainwater for drinking or cooking.
If you are concerned that mosquitoes may attempt to colonise your rainwater tank, you should ensure that overflows and tank inlets are covered by screens. This will prevent mosquitoes from entering the tank to breed.
If you plan on using your rainwater for drinking purposes, it is a good idea to install a system which is specifically designed for this. Some systems contain filters that are designed to make water safe for drinking. You could also install a reverse osmosis unit to purify water before drinking.
In some cases, a plumber may fail to ensure that a rainwater system is properly isolated from the mains supply. The plumbing Code of Australia requires such systems to have a backflow prevention device or visible air gap in place to prevent rainwater from flowing back into the mains supply.
Where rainwater can be collected for domestic reuse
Roofs and gutters
Most roof types are suitable for the collection of rainwater for reuse, though you need to consider the quality of rainwater required and ensure that your roof meets certain standards.
For lawn or garden irrigation:
• Rainwater can be collected from any roof except those composed of unsealed asbestos
• Ensure that roof gutters fall towards outlets
• Fit a leaf screen on gutters to ensure that sediment and other material does not build up in the system
For drinking and cooking:
• Avoid collecting rainwater from roofs or roof sections that may contain asbestos sheeting, lead flashing, or pre-1980 paint. Roofs containing these materials may be sealed using a potable-quality roof sealant. If you have sealed your roof with a sealant, avoid collecting any rainwater for reuse until a few rainfall events have passed and rinsed the roof
• Avoid collecting rainwater for drinking purposes if there is a chance that airborne toxins or chemicals may be present, for example, in areas where industrial or chemical processing is occurring, or crop dusting.
If you need professional help on your stormwater matters, contact us on 0412 738 874 or leave a message.
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