We have also recently built a rainwater collection system on the back of the barn.
The barrels were purchased from the local Scouts who were having a fundraiser. SInce you need to get a bucket under the taps at the bottom, we built a platform. It's big enough for 3 barrels and made from mainly leftover wood we had lying around.
We live on the Canadian Shield. Getting those posts in the ground was not happening, hence the cement bases. If you had ground you could actually pound a post into, you could do it that way.
Putting eavestrough on the back of the barn was not obvious either but we managed.
We had to sort of gerry-rig a facia board to screw it to. And the barn and lean-to are not in line, hence the s-bend to drain water from one into the other.
We need to manually change which barrel the water flows into. I suspect one could figure out how to get the overflow from one to go into another but we were stumped and this seemed easiest.
These are located at the back of the shelter the pigs are sleeping in. We've put their drinking water container just off to the left of it so this makes it much easier to get water to the pigs.
Pigs are thirsty animals (one theory as to why many desert cultures have a taboo on eating pork) so being able to use rainwater is also a bonus. And this year we have had quite a bit of rain.
We plan to figure out how to put eavestrough on the front of the barn and where to collect that water. We were thinking we could run a gutter back to join these but now I'm wondering whether it makes sense to have another set of barrels at the front. I think the water coming off the back will easily fill 3 barells.