My friends had a 310 litre blue food barrel cut diagonally over it's length to giver two halvers with a drain point at the end of one . The diagonal half was set in a simple wooden cradle that Don made with the frame on skids. Done so the ducks could walk up a 15 inch wide gang plank to get in & out at the shallow end .
Once a week he'd drain the thing , power or hose wash it , move it to a new site and refill it .
Don said that this was his best solution to stop the ground getting muddy in wet weather . It also allowed him to pull it around the orchard to a new site thus fertilizing the orchard bit by bit & keeping the weeds & grass down .
His ducks & geese had night time closed up shelters with slatted floors for ventilation as much as anything , they were also on skids for the same reason . He made them so the tops hinged open to one side to allow him to clean the slats off , before moving them on to a new place.
Don helped me set up with four geese his best advice was :-
Whatever you do start feeding them long before the grass loses its nutritiousness , often a lot of ducks & geese are almost starved before a lot of owners realise it .