It's certainly possible; boiling water can melt or loosen the gunk holding the clog together.
For tough clogs, use a full cup. While that sits, bring a half pot of water (about 4 cups) to boil. Pour this directly into the drain very slowly but steadily to avoid getting burned by splashing water. Allow to sit for 10 to 15 minutes, then run water down the drain to check how freely water flows.
Pouring boiling water down the drain to unclog it most likely won't work. Sure, there's a very small chance it could loosen the clog, but there's a larger risk of softening or melting PVC joints.
For minor clogs, try boiling a large pot of water. Because the boiling temperature of the water is 212 degrees Fahrenheit, it is too hot for direct contact with porcelain sinks and PVC pipes. If you are sure your sink and pipes are neither of the above, slowly pour the boiling water directly down the drain.
Once a week, flush your drain by boiling a large pot of water. Pour one-half of the pot down the drain. Wait five minutes and pour the rest. It's a simple thing that can help dislodge any grease or debris lurking in your drain.
When you are using a baking soda and vinegar solution to clean out your drain, you are actually causing the rubber and plastic that are used for the drain's pipes to be eaten away by the mixture. Over time, this rubber and plastic will break down, causing the drain to become even more blocked.
Salt & hot water
While hot water can help loosen up debris, coarse salt actually scours the inside of your pipes, removing more material than hot water alone. After removing standing water from the sink, pour about half a cup of table salt down the drain before you pour in the hot water.
In modern houses some of the drain pipes are PVC plastic, and usually the boiling water will just flow through it without causing any damage. But if it goes through the pipe slowly the PVC could the deform.
Pour Hot Water into the Toilet
If you need to heat some in the microwave or the stovetop, you don't want it to reach boiling temperatures. Boiling water can cause toilet porcelain to crack. Allow the hot fluid to sit in the toilet for a few minutes to loosen the clog.
A lot of folks know the baking soda and vinegar trick. Simply pour some hot water down your clogged drain and follow it up with equal parts baking soda and vinegar (baking soda first), cover the drain with a plug if you have one, let it sit for 20-30 minutes, then follow it up with more hot water to clear the clog.
Homemade drain cleaner can break up even the toughest clogs in your sink. Baking soda, vinegar and Dawn dish soap along with boiling water can safely unclog a drain.
Pour or squeeze ½ cup of Dawn® dish detergent down the drain. For a tougher clog, use 1 full cup. Let the detergent work its way down the drain for 30 minutes.
Hot water will break down the grease better and when aided by a cleaning agent, grease is a goner. While cold-water jetting can bust through a blockage, you will not truly clean a pipe and rid it of the FOG buildup unless you clean it with hot water.
Preventative Maintenance
Pouring bleach into the drain when the unit is not operating can leave residual bleach, which will damage the drain pan and line. Using vinegar for preventative maintenance throughout the year will keep your drain clean and clear and will not damage your line.
Baking soda, vinegar and boiling water can help clean drains naturally, but you may need something stronger, like Liquid-Plumr, to fully unclog those really tough drain clogs.
Professional Plumbing Tools 101: Drain Augers
Also known as drain snakes, there are several different versions of drain augers that most plumbers will carry with them at all times. In essence, it's a basic tool, but an auger is best for tough drain clogs that just won't budge and for cleaning out drains, too.
Hot Water and Dish Soap
Wait for 10-15 minutes while the dish soap and hot water soften the clog. Once you do so, the toilet will unclog and flush freely. Alternatively, you could use hot water and shampoo from the sink if you wish to clear your toilet without leaving your bathroom.
Leave drain as is for about ten minutes, while you bring a couple of gallons of water almost to a boil. Note: Boiling water could crack your toilet bowl, so heat to just under boiling. Carefully pour hot water into the toilet bowl from about waist height to create enough force to push the clog through.
Stay ahead of erosion and corrosion by having your pipes inspected annually. Also, keep in mind that hot water has the potential of causing the soil around your outdoor pipes to move, which can damage and even break the pipes. This is especially true when the weather is dryer.
Boiling water is one of the simplest methods to address the issue of drain flies. Boil a medium-sized pot of water and pour it down the drain to eliminate gnats and other drain insects. Repeat this method once or twice a week for good results.
First, make sure there is no water in the sink. Pour one cup of baking soda followed by one cup of table salt, and then pour a cup of white vinegar. Wait for ten minutes and then flush it with boiling water. After that, the drain should be clear!
Baking Soda + Salt
Mix 1/2 cup table salt and 1/2 cup baking soda together, and pour down drain. Let sit for about 30 minutes (or overnight if it's a tough clog).
Coke and Pepsi are loaded with phosphoric acid, which breaks down the buildup that can clog your drains! Phosphoric acid can even remove lime scale and another tough buildup that regular cleaners struggle with. This is an effective and refreshing home remedy if we ever saw one!