We are in a severe drought,my grandkids have a baby pool @ my house.I can get debris out but what about bacter

Can you treat the water for purification with thimble of clorox or something safely? Our drought situation absolutely doesn't allow any use of water for recreational use.The water of couse becomes stagnant after a while.I do have it covered securely and keep it debris free,but I sure love these babies and they really love their little pool.It's only 6' in diameter and 6" deep.Ant chemists out there that can tell me something safe and effective?