sofa

Q: My neice diaper leaked and i did not know... I allowed her to sit on the sofa and as soon as she sat, a spot appeared on the sofa, I asked her to get up and changed the diaper. As a precaution I wiped the place with surf and then with a wet cloth. The next day I cleaned the sofa by pouring water over the spot three times. Has it become paak because my mother offers prayers by sitting on that sofa thats why I am concerned? Plus the water reached on the lower part of the sofa which becomes a bed. Does that part become napaak as I read somewhere that if you clean something with a jug of water, the water which flows is napaak? Keeping in mind it was just a spot which did not go on the lower part of the sofa. Also explain for the future how to clean a sofa matress, etc. if a child urinates on it?