"Jennifer" wrote in message
...
We get so little rain here, in the spring/summer it can go 3 - 4 months
without a drop. I was looking at the 40 - 50 gallon size.


This might help water one pot plant. What did you have in mind that you
would do with this much water? If you have a garden a tank 10 times as big
might start to be useful, 50 times would be better.

Did you make your own or did you buy one?
Can you connect a hose to your spigot?

This is only useful of there is fall from the barrel to where you want the
water. A bucket may be much simpler for this volume.

Do you have it "anchored" to you home... for example what
keeps it from blowing away in a strong wind if empty?

Depends what it's made of, the shape and where it is

I'm assuming I
will have to cut my drain pipe, any hints on that?


Depends on what the drain pipe is made from and how it is connected to the
roof plumbing. Consider also that it will not take much of a shower to fill
your barrel (depending on how much roof area drains to that downpipe).
Where will the overflow go?

Jennifer


Your questions suggest that your experience is a long way from basic
plumbing or even the fairly simple concepts behind it. Perhaps there is
somebody around who is of a more practical frame of mind who could have a
look at your house and garden and give advice to get you started.

David