First Solution: Raise the level of your water butts
If you can't raise the level of your water butts, follow these steps...
(See large diagram below)
Step 1: Ensure you connect at least one water butt at the correct level to your RAINPOD.
Step 2: Add a 25mm 90 degree overflow bend at the max water level you would like to fill your first water butt(s).
Step 3: Ensure your rainwater diverter is HIGHER than the water level in step 2.
Step 4: Connect your hose to the 90 degree bend in step 2 and connect the remaining water butts in the lower garden section.
Step 5: Add an addition water butt tap to any of these water butts to access your lower level water or install a water butt pump.
Step 6: Add an overflow to one of these water butts. This will serve as your main overflow to your system.
If you wanted to hide the lower level water butts, simply add a RAINTAP to access your water in a more convenient location.