1. The only thing you should ever use a plunger on is a toilet bowl!
Do not use a plunger on any other drain. The pipes underneath sinks are not made to withstand that kind of pressure. Just recently, we got a call from a home owner who had a clogged kitchen sink and she used a plunger and cracked the pipe underneath the sink. Not only that, her drain was still clogged. Only use a plunger on a toilet.
2. Only plunge a toilet if the clog is from organic matter (poop).
If the clog is from non-organic matter, such as cosmetics, sanitary items, jewelry, toys, candles, etcetera, plunging may push the item further along the line, making it more difficult and more expensive to clear the line.
3. If you know the clog is from organic matter, plunge like you mean it!
You can’t be afraid of getting splashed with “dark” water. You can always take a shower after the ordeal. If at first you don’t succeed, try waiting a few hours or all day or night for the water to soften the clog, and then try plunging again. It may be you don’t even need to plunge after 24 hours if the poop has softened. Flushing alone may work. The goal in plunging is to create a suction in the piping below. Slowly push the plunger in and try to create a seal around the hole at the bottom. Once you create the seal, firmly push back and forth without breaking the seal. This will loosen the clog from both directions and help break it up to be able to flow through the trapway. It will also greatly reduce splashing.
4. When the toilet is clogged and you try flushing and the bowl is full of water, this is the best time to plunge.
If the water level is very low, you may need to add water to the bowl by flushing again. Note: If you have an old toilet and your toilet is not flushing, then be prepared to stop the water flow, because an old toilet flushes with 3 & 1/2 gallons of water. This could possibly overflow you toilet. The newer toilets usually do not have this problem if the water level is all the way down. You can usually flush them once and it won’t overflow. How do I know if I have an older toilet? If my house was built after 1994 then is it almost certain that you have the lower flow toilet. Before 1994, you may have the older toilet, unless you have had it replaced.
If all this fails, then it may be time to call in a professional. Sometimes tools and experience make all the difference.
If someone in your household has a reputation for clogging the toilet, explain to them that they must NOT drop in a full load before flushing. Drop some, then flush. Drop some more, then flush. Repeat until finished.