The drums are closed,not open . I have piping from one drum to the other which the water passes and there is a tight seal. I have a manifold pipe from drum to drum with valves to open and close each one. I've been using a sump pump in another drum as the pumping station, but the sump just isn't strong enough for the distant. If you have a idea or though on a better pump other than a old cheap pool pump I would like to hear of them. This will only be used a few times a summer , just had another idea maybe I run lines to the water closets also,that will save on water down the drain.
Thanks for your concern about the barrels becoming mosquito-breeding pools.