On Tue, 10 Aug 2010 07:42:05 -0700 (PDT), Jonathan wrote:

You will store more water if they are level and joined as low as
possible.

Correct and in the interests of not letting the water stagnate there
might be some sense in taking the water from Butt 3 rather than Butt
1. Also make sure the butts are opaque and have well fitting opaque
lids otherwise they will grow some lovely algae. though I guess for
garden watering that isn't much of problem but may increase a
stagnation problem.

--
Cheers
Dave.