Putting together my rainwater collection systemThere are basically two components to be considered for rainwater collection.
In preparation for my backyard water features and fernery I needed to build a new shelter for my lawn mower, wheelbarrow and the like. This shelter also included a small section of roof which was ideal for practicing the plumbing skills I needed to aquire! Because the shelter roofline was not much higher than the lower of my two rainwater collection tanks (see below), I put a new piece of 60mm PVC downpipe directly from the shelter gutter into a hole of the same size in the lid of the tank. I then had to instal an overflow from the top of the tank to the stormwater system. My second tank is to be used as a 'header' tank so I wanted to install it as high as I could but still collect rainwater by gravity. I did this by mounting it on a tank stand so that the top was positioned directly below the existing roof gutter. Again I installed a short downpipe directly into the tank. However this time I also installed a hinged cover over the hole leading into the downpipe which allows me to divert the rainwater collection if the tank is already full. Another method I considered was to purchase a rainwater diverter which I could place into the existing downpipe and run the diverted water onto my shelter roof. This diverter also contained a simple on-off mechanism. Rainwater Storage - tank selection There are many excellent storage tanks available for rainwater collection that have been specifically designed and built for the suburban backyard. They come in many shapes, colors and sizes. Because of my limited budget I decided to investigate used tanks as well as adapting other containers that I might be able to get cheap and compare these alternatives, if any, with the commercial rainwater tanks. Despite keeping an eye on the freecycle emails I receive there were no offers of vessels suitable for rainwater collection. Next I searched ebay for 'water tank', 'rainwater tank'and located second-hand conventional tanks and other containers that could be adapted for this use. My search was also limited by another factor - Because my backyard can only be accessed via the 800mm wide backdoor to my garage it means that if I were to use the conventional cylinder shaped water tank it would necessarily be of very small capacity. For instance I found a number of offers of 1000 liter plastic cube shaped containers previously used for chemical srorage on farms. These had a supporting aluminium cage and their owners had been using them for rainwater collection. However with a dimension of 1100mm they had to be discarded for my use. Under 'water drums' on ebay I found some barrel shaped plastic drums of about 200-250 liters for $20 and this got me considering their use as a 'header' tank to be used in conjunction with a larger underhouse bladder tank. The bladder tank has a lot going fot it. One model has the largest capacity (2000l) of any of the containers that can fit through my door (empty of course) and
Unfortunately at this time they are relatively uncommon so there is no second hand market and their price new put them outside my limited budget. Another possibility considered was a used water filled plastic crash barrier. I'd observed these being used on construction sites and a Google search revealed that they were commonly hired out by plant hire firms for the legth of the project. I didn't get around to pursuing their used availability. My conclusion was to use the chemical storage barrels. Even though they are on the small size at around 200 liters they are:
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