All of our toilets seem to be running on low water in the bowls. The tanks are full. I see no leaks. You have to flush several times to even get toilet paper down sometimes! Then the water slowly leaks out until there is less than half the amount of water. My husband replaced the flapper (wrong word?) in one of the toilets on the top level of the house, and then this problem seemed to start. We also have hard to very hard water and it is very cold where we live. Not sure if any of those things are relevant. Please help if possible. Thanks!