The 15-Minute Fix
Start by taking the lid off the toilet tank and setting it somewhere safe. Then flush the toilet once and watch what happens inside as the tank refills. You’re looking for anything that doesn’t seem to reset properly after the flush is done. If the flapper at the bottom doesn’t close fully, press it gently into place. Sometimes it just isn’t sealing properly. If the chain looks too tight, twisted, or caught on something, loosen it so the flapper can drop naturally without being pulled upward.
Then check the water level. If the water keeps rising high enough to spill into the overflow tube, adjust the float slightly downward so the tank stops filling a bit sooner. On many toilets, that can be done with a small screw or clip adjustment depending on the model. Once you’ve made those changes, flush again and wait. If the water stops running and the tank fills normally without continuing to trickle, you’ve probably solved the issue. And in many cases, that’s all it takes.
Not a plumber. Not a major repair. Just a quick adjustment most people never realize they can do themselves.