Our house is ~20 meter long with on one side over the whole length a gutter. On both ends, I've connected 200L rain tanks, that will collect any rain into these tanks if they aren't full. I've cut out ~10 centimeter and installed the connector that came with the rain tank.
Two on one side (connected to each other), and one on the other side.
When it's raining hard, the gutter is overflowing around the center. This causes water to get under the roof (metal roof) and has caused leakage in one of the rooms.
I've cleared out the gutter, my suspicion is that due to the rain tanks the flow rate has decreased, causing a water build up in the middle. Is that a reasonable assumption?
It only seems to happen in the center, so it may also be that it's not 100% level & it's slightly lower in the middle.
Any thoughts and possible solutions? Hopefully there's an easy solution, e.g. installing a pipe in the middle will require me connecting it to the storm water, which won't be easy.