I have four chickens, different ages. Whenever I clean out their water by dumping it on the ground, they all rush over like I'm giving them the best treat ever and start drinking from the ground. If I kick dirt in the water and make it into thicker mud they think that's even better. It's probably a natural chicken behavior and I don't think they are deficient, they get both crushed up eggshell and oyster shells, but I'm worried about possible lead in the soil if they start eating too much. Any suggestions on how to stop them? Just wondering...