I've had a few people asking about the rainwater harvester on my allotment in the village, and specifically how it was put together. Like many others I'm sure, I couldn't really bring myself to spend £35-£60 on a water butt that could only hold 210L. Similarly, whilst I'm only about 5 minutes walk from home it didn't seem right to be walking to and fro to water my plants with tap water.
This is where I came up with the idea of using an IBC container. These are 1000L containers, many of which transport food-based contents such as food extract and once they have been used once, they're surplus to requirement. You need to make sure that the containers are food-safe because there are some of course which are used to transport oil and fuel-based liquids.
There are companies which sell second-hand containers online, but personally I used Facebook Marketplace (https://www.facebook.com/search/marketplace/?q=ibc%20container) and found a container locally which cost me £40. They come in 600L and 1000L varieties, and usually with a pallet on the base. Many suppliers sell tap and hozelock adaptors to fit on the front also which is just what I was looking for. My plan was to use gravity-fed pressure to drip feed my plot on a timer.
The frame was quite simple to build, with the appropriate slant for the roof, and sufficient width to support 3 full size corrugated plastic roof sheets.
The posts and support were all purchased from Mole Valley, and pressure treated to provide some longevity. Whilst it wasn't necessary I decided to concrete in the posts for extra support as I didn't really want the frame collapsing in the winter weather.