I use a Little Tikes sand pit [it has a lid] that I found at the side of the road. It is more robust than the blue kiddie pool that I previously used and has lasted longer being emptied and hosed down regularly than my original blue kiddie pool.
Finding that the green imitation turtle pit was better than my blue kiddie pool had been, I advertised on NextDoor for one for my son's ducks and within 2 hours of posting, I had been given a second one. Grandchildren outgrow sandpits and I found, by advertising the need for a duck pool, grandmothers like ducks too.
We cover our pools at night to stop raccoons fouling them. My son's needs emptying and hosing down every day -- he has a lot of soil that the ducks can get at and eat and then come to the pool to drink; his ducks also like bathing and splashing in the pool several times a day. My pool only needs emptying and hosing down every few days. the area round my pool is heavily mulched and so it doesn't get the dirty bills washed in it. My all-male flock are also not big on bathing: I have to hose them down to get them to finish off in the pool. Stinky boys!!!
There are two red bricks and a curved edging stone for the little crested to get into the pool, but she insists on getting in over the side like the bigger ducks. The pekin and muscovy do use the curved edging stone but have no need to as they are agile enough to get in over the side without trouble.
When they were ducklings -- they were given free access to a pool from 8 weeks -- they had bricks inside the pool to stand on to get out -- they didn't seem to need the bricks, but it was a safety precaution in case one should get water logged.
