We live in an older two story home for 25 yrs. For the past 6 months we have had problems with both toilets on the 1st and 2nd floors not flushing properly. When we flush, the water in the bowel rises high and then either flushes completely or it just swirls around and doesn't go down the drain. We've plunged a number of times without much success. When the water doesn't flush initially, we try by flushing again and at the same time pour a bucket of water into the toilet and that always works. Very odd that that works but plunging doesn't. Any suggestions what the problem may be?