Gross!
I know! It's cause he likes fresh water and is used to "hunting" for it outside LOL he has a bowl but he'll drink out of little planters, the cover on the fire pit, the stairs, tables, etc. Any little pool of water. He loves rain water. So now he has taken to hunting for it inside. Sometimes I tell him no and he walks away thankfully, he's a good boy, but then he always looks so confused and hurt and I feel bad so sometimes I end up giving it to him anyway or just not saying no lol they are on a table next to my chair.