"Ed" ex@directory wrote in message
o.uk...
The first water barrel (A) on my allotment is at the top of a slight
slope and is fed by rain water gathered from the roof of my shed. I want
to put in a second barrel (B) in a direct line (no bends involved) from
the first barrel and down a slight slope. Both are fitted with taps, but I
would always prefer to drain the water from the lower barrel B as it is a
little more accessible. How best to connect these?

I have options to run a connection pipe from the upper barrel (A) to the
lower barrel (B) as follows:

1. Connect from top of barrel A to top of barrel B

Top to top seems best.
As already noted it depends on the difference in heights.
If there is no difference then it may not matter (but you imply B is lower
than A).
Bottom of A to any part of B will only fill A to the top point of B.
Top to top fills both barrels to the top and also lets any sediment settle.

You could always go for more than one connection.

Connect top to top so that both barrels fill fully.
Then connect the bottom of A via a tap to anywhere on B.
This allows you to run water from A to B when B is empty without
compromising your ability to fill both barrels to the top.