You better check your local laws because catching rainwater is illegal in Colorado.
Your kidding right?
Thankfully it is still perfectly legal to catch rainwater in Washington. And if they change the law the bastards will have to Grandfather me....
An important point to note is that this tank does NOT contain potable water. Potable water is defined as water that is safe for drinking by human beings.
The tank does contain FRESH water, in that the water does not contain any salt. Desalinization is much different from purification, and there is a great difference between the two and it is important to make that distinction.
However, in an emergency this water is perfectly good for filtering and purification by whatever means you plan on using. There are many different filtering systems out there, and this thread is not about which of those is best. I am just trying to demonstrate one fairly simple way that anyone can simply and economically harvest what God lets fall from the sky for any use you have for it.
Good! I'll be building one in my yard this summer then.