Rain Water In Melbourne
Rainwater tanks reduce the physical impact of storm-water on drainage infrastructure, roads, urban streams and beaches and mitigate flooding. They also contribute to reducing contaminants in our waterways. Retention of rainwater allows for its reuse for outdoor use such as gardening and washing cars. When integrated with household plumbing and by using a pump, a rainwater tank can also supply water for other uses. But it is also highly desirable to use rainwater for all domestic purposes, including drinking, cooking, bathing and in hot water systems.
Its the decentralised solution to Melbourne’s water crisis. Everyone with a roof and a gutter can direct the rain runoff into their own tank, vastly reducing the net demand on the Melbourne Water Catchment. If everyone that were able to, actually did switch to tank water, then Melbourne Water (through the SCA) could supply the city on 14% of Thomson Dam’s capacity alone.
So now you’re aware of the advantages of self collection and storage of rain water. But you want all the details, well here they are.
Is It Safe To Drink?
The short answer is that in almost all cases in Melbourne YES it is, however in certain locations that are close to major industrial polluters/emitters then chemical filtering or atleast measurement is the best course of action.
VIC Health’s official line
“A properly maintained rainwater tank can provide good quality drinking water. Occasionally there are cases of illness from contaminated rainwater. In urban areas the public water supply remains the most reliable source of drinking water for the community. In these areas VIC Health supports the use of rainwater tanks for non-drinking uses. VIC Health recommends that people use the public water supply for drinking and cooking because it is filtered, disinfected and generally fluoridated.”
The safety of rainwater will depend on excluding or minimising the presence of enteric pathogens. Enteric pathogens include types of bacteria, viruses and protozoa. These organisms do not grow or survive indefinitely in water environments and are introduced into drinking water supplies by contamination with faecal material. Microbial quality of drinking water is commonly measured by testing for Escherichia coli (E. coli), or alternatively thermotolerant coliforms (sometimes referred to by the less accurate term faecal coliforms), as indicators of faecal contamination and the possible presence of enteric pathogens.
To minimise and most likely eliminate the impact of microbial hazards it is recommended to exercise an excellent maintenance schedule and use the first flush system. The first flush system automatically disregards some initial quantity of rain water (usually 100-500L for medium sized roof) that is most likely to contain built up residue, sediment, organic and decomposing materials that may have accumulated in the catchment system from the previous rain event, subsequent rain water should be quite clean.
Chemical hazards include pesticides, fungicides, herbicides, hydrocarbons and volatile
organic compounds, phthalates (plasticisers), phenolics, polycyclic aromatic hydrocarbons (PAHs) and trace metals. Impacts from major industrial emissions, may result in tank rainwater not being suitable for drinking and food preparation by particular vulnerable groups, such as pregnant or breastfeeding women and young children.
Ok all this science is scaring me how can i be 100% safe?
Well to remove microbial hazards water can be boiled, but to remove chemical hazards such as heavy metal poisons like lead(Pb), mercury(Hg) and arsenic(As) an ion exchange filtration system is required.
To play it safe the take home message is that inner urban Melbourne and any industrial adjacent suburbs should use either chemical measurement or filtering. If filtering/measuring water quality is cost exclusive, you may still want to consider a tank for purposes outside of drinking such as: clothe and car washing, household cleaning, vegetable and other garden watering, hot water supply, showers and baths, toilet flushing. Everything bar cooking and drinking.
Setup And Costs
Gutters, Pipes and Plumbing
The volume of rain water you can collect will depend on roof area. To get setup you will need to connect the gutters to the down pipes and plumb them into the tank. Generally this input side of the system is gravity fed thus the top of the tank (rain water entry point) is required to be mounted lower than the gutters, allowing roof run off to free flow into the tank. The cost of this will largely depend on the size and complexity of your premises and is best determined with a quote from your local plumber.
Tanks can get pretty big so the storage capacity of the tank you get may be limited to the size of your block, or more correctly the free space available to install it in. Tanks come in alot of shapes, capacities and materials. From 1000L at around $250 up to 50,000L at around $4000.
Since it is common to mount the tank low, then the output water flow most likely can not be gravity fed, instead a pump is required to push the water through the plumbing system.
The cost of a pump can typically range between $800 and $3000 depending on your specific requirements. A good pump should be guaranteed to last atleast 10 years.
Where to now
For more information on this subject see the following page, it contains handy tips you will need to get started, and professional advice on installation.
We recommend the 24 Hour Emergency Plumbers Melbourne, they role out full installations, do professional repair and maintenance on all plumbing aspects, they can even help during the design phase of a new house or apartment block.