Can you do it yourself a large rainwater harvesting system for not a lot of money? Yes you can! Start with used IBC Totes. I will summarize in this article and then go into detail in the future parts.
Begin creating a big rainwater harvesting system by finding a used 275 gallon IBC Tote supplier. Get as many tanks as you think you need. You will be linking them together for a combined capacity. I have 9 for a combined 2500 gallon. Cost was about $80 each so it was less than $1000 which is much less than a dedicated tank of the same size.
These are the white plastic bladder with aluminum cage system that you might see in the back of a truck. They come in 2 types mostly for holding something industrial like hydraulic oil or food grade. You can tell the difference by what spout or valve they have and at least locally the lid color. The green lid is food, the black one is things like hydraulic fluid. The food grade the end of the spout/valve is ‘coarse thread to NPT’ connection, the other has a ‘buttress adapter’. These are important because you will be building a PVC plumbing ‘outrigger’ to connect more than one IBC tote.
You buy the proper buttress adapters and/or coarse thread to NPT adapters at something like Northern Tool or Amazon. Then at your home store buy 2 inch female NPT to slip socket PVC connector, 2 inch PVC pipe and 2 inch 90 degree elbows, pipe and as many ‘Tees’ as you need. Also buy a 2 inch PVC valve for a main drain. Get the ‘pressurized’ PVC fittings not the ‘non-pressurized’ PVC fittings. The slip socket is twice as deep for pressurized then non-pressurized. You will have leaks with non-pressurized, guess how I know.
Get the tanks into position, connect all the fittings together at the same level as the valves, add your main drain valve and you are mostly done. The last step is to drill holes and add buttress openings to the top of the lowest tank so that when it fills up it will automatically spill in a controlled fashion.
That is mostly it! More details and pictures in the next article.