How to Improve a Toilet's Flushing Power

Unclogging the Toilet

Look for signs of a clog. If the toilet abruptly fails to drain, or drains only very slowly, it is "clogged".

Wait for the excess bowl water to seep down. Then try a plunger.

Try a plumber's snake (ideally with curved toilet bend adapter) for stubborn obstructions. These can include normal toilet stuff, near-normal stuff like wipes and towels, and trinkets from kids and the adults who blame them.

Increasing Flush Volume

Look for signs the flush is too short. If the toilet fails to empty completely, returns some contents to the bowl, or tends to clog after repeated heavy use, it's probably not flushing long enough. The flush should continue for a second or so after the toilet contents disappear, to carry them over the bends and down, down and away.

Check the fill valve and float. If it has been adjusted to not allow the tank to fill completely (to within an inch or so of the top of the overflow tube), adjust it up a bit.

Remove any objects, such as bricks, bottles, and booze, reducing the volume of the toilet tank. (The former are often added to save water, but not using enough water can require multiple flushes, cleaning, and general disgust and inefficiency - which you don't want to lead to the latter.)

Check the float flapper. A toilet flapper with a foam float halfway down is a simple, inexpensive, fairly effective way to make a low-flush toilet: the foam float on the chain, instead of a little cup under the flapper itself, holds the flapper up and open only long enough for the bottom half or so of the tank contents to flush it, with the weight of the top half on it to increase speed and power. But, if the float is too high on the chain, the flush will cut off too soon to do its job. Gently nudge the foam float down the chain a half-inch or so at a time until the flush lasts long enough.

Decalcify an Old Toilet with Acidic Cleaner

Try an acidic cleaner. Very old toilets may accumulate hard water deposits that narrow their passages and cause water to drain out only slowly. If your toilet's flush seems more hesitant than your friends', try some muriatic (hydrochloric) acid or other calcium remover, adding a little water at a time to push it into the bend to attack the deposits.

Remember that strong acids and their fumes can be dangerous and corrosive. Run the vent, and flush the toilet before using.