Plunge Out the Water
After shutting off the water supply valve, place the flange of a toilet plunger (also called a closet plunger) firmly into the drain hole in the bottom of the toilet bowl. Plunge with an up-and-down motion to get most of the water out of the bowl. This should force out any clog into the drain.
Another possibility is that the flapper valve that seals between the tank and the bowl isn't sealing properly, allowing water to constantly leak into the bowl. If it weren't for the blockage, you might never notice this leaking issue, because the toilet will flush itself when the water in the bowl rises high enough.
If the water level is too low, you may end up with frequent clogs because there isn't enough water to properly flush the toilet. If it's too high, your toilet could become dangerously close to overflowing every time you flush.
Will a toilet eventually unclog itself? It sure would be nice, but it's fairly rare for a toilet's clog to clear up after a few hours. It can happen, but only in select circumstances.
The most common cause of a toilet that doesn't drain properly is simply that it's clogged, which itself can happen for any number of reasons. Typically, using a plunger is enough to dislodge the clog and allow the water to drain properly. If that doesn't work, you may be dealing with a different issue. Venting issues.
Caustic soda is a nasty chemical that can burn, but it's very effective for unclogging toilets. To use this chemical, you need to get some rubber gloves and eye protection. You can pick the chemical from the local hardware or grocery stores. Pour a ¾ gallon of cold water into a bucket, and add 3 cups of caustic soda.
You can use Drano® Clog Removers to unclog a kitchen sink, bathroom sink, shower or clogged bathtub, but DO NOT use them in toilets. For clogged or slow-running drains, apply the product and let it work 15 minutes, then flush with hot water.
Clogged Drain: The most common cause of a toilet filling up with water after flushing is a clogged drain. When a drain is clogged, water cannot flow through it, causing it to back up and fill the toilet bowl. You can try using a plunger or a plumbing snake to clear the clog.
Can Toilet Paper Break Down Eventually? In most scenarios, water dissolves paper over time. After all, it's designed to break down in the water. In other words, if you tried to flush the toilet and didn't succeed, you can always wait around 15 minutes to try flushing again.
Examine the toilet tank's float height.
The height of the float determines how much water remains in the tank after it refills. It should be at the water level if it is not broken. If the float appears too high or low, adjust the float height and when you refill the tank, check how it changes the water level.
Is it okay to leave a clogged toilet overnight? In most cases, you can leave a clogged toilet overnight. However, calling an emergency plumber near you might be warranted if water starts leaking from the pipes. A simple clog likely won't cause this, but an inexperienced homeowner messing with the plumbing could.
Aside from vinegar and baking soda mixture, applying bleach is one of the easiest and cheapest methods for unclogging a blocked toilet.
For preventive drain cleaning, you can use Drano® Max Build-Up Remover in drains, toilets and even septic systems. Apply Drano® Max Build-Up Remover overnight or before you go to work, then wait 6 to 8 hours before running warm (not hot) water down treated drains or flushing treated toilets.