No more stinky water butts in your garden.
Step 1: Fitment
Fit a water butt of your choice as normal
Step 2: Feed Pipe
Instead of fitting the feed pipe to fill from the top, increase the length of it so it is about 4 inches from the bottom of the water butt.
Step 3: Circulation
As a top filled water butt simply fills to spill, all the water at the bottom never moves or is rarely disturbed. This leads to it stagnating and becoming a very unpleasant experience when using water from that tank.
Increasing the length of the feed pipe to just off the bottom of the tank, will fill up from the bottom and circulate out the water every time it rains.
No unpleasant smelly water when used.
No need to add chemicals
No need to drain the water out to refresh it.
Hydrostatic pressure of the water column in the feed pipe will be equal to the pressure in the main body of water. Water will obviously always find it's own level and so push any horrid water up and out of the water butt.