My run has 6 inches of sand and is covered by a roof, so up until recently I never had any drainage issues. Then I added a pop door from my Pekin coop into the run, and let my 7 Pekin ducks into the run with my chickens and mallards. The Pekins proceeded to drain my three 5 gallon waterers onto the ground, and after a few days of repeating this routine, my sand floor was a swamp with standing water in the low spots. With winter coming on, I knew I needed to find a solution or I would have major ice problems in a month or two. So I decided to add a drainage system to the coop, and build catch basins for each of the 3 waterers and the two open bathing bowls. The basins are built with 2x6 walls and galvanized steel bottoms that are V shaped with a 1.5" PVC drain pipe at the bottom of the V which drains the water from the catch basin and takes the water outside the run. The catch basins are filled with large river rocks, and the waterers are placed on an octagon paver for a little extra height, So far so good, my sand is dry again, and the water now drains outside the coop. It took me a few hours to build the 5 catch basins, and 3 hours to install them. Hoping this may inspire anyone who has drainage problems, and wants their coop to have better drainage than their house!