Rainwater usage ( 1999 )

As I have a nice garden and we have enough rain, why not use the water?
From idea to solution it took a while and a lot of small things had to be solved.
One was the fact that we have lot's of cold days in winter, so I want to have the tanks empty.
That why I made the "valve" in picture 3 and 4. As in closed position the level of the "valve" is higher than the collector ( green plastic tube )no water can pass.
Another was a way to connect the srcewed outlets to a tube system. You can see that I solved it by manipulation of a standard part.