When dealing with clogged drains, be it from fat, food, or anything else, pouring boiling water straight down them might sound like a good idea, right? Well, warn our plumbing experts – wrong, very wrong, particularly in winter.
The reason is simple. Pour boiling water onto anything cold, and you risk thermal shock and breakages, and the same applies to your pipes, too.
Why You Should Never Pour Boiling Water Down Drains in Winter
If you haven't yet found an effective ways to stop pipes freezing, Devin Conley, founder and CEO at Mountain Standard Plumbing warns against turning to sudden heat. He says, 'Boiling water and winter pipes is a disaster in slow motion. What most homeowners don't realize is how brittle their pipes get in the winter.
'This is what I see all winter, every winter. That shot of 212-degree water down the drain hits pipes that may be only a degree or two above freezing, depending on insulation and exposure. With PVC, which has become the norm since about the 1980s, that's bad news.
'PVC starts to soften at 140 degrees. At 212, it can sag and develop hairline cracks at joints and bends. Plus, if the glue bond at joints is compromised, or the rubber gaskets soften, you may not notice until water starts leaking out from under the sink or through the wall.'
Devin reveals that in winter, this amounts to a double danger as cold pipes sag away from glue joints or gasket seals, and thermal shock from boiling water closes the gap with jagged edges.
'The net result,' Devin explains, 'is a drip that often goes unnoticed for weeks or months, soaking and rotting woodwork.'
So, not only will pouring boiling water down the drain leave you wondering what to do if a pipe bursts, but it can also secretly increase the risk of mold and mildew in hidden spots with a slow leak, and you won't know about it until it's too late.
Josh Mitchell, HVAC pro and founder of AirConditionerLab, agrees, warning that, though PVC pipes are most at risk, copper and cast iron are not immune, either.
'They last longer, but repeated boiling water over cold pipes in winter can create stress fractures or small leaks at the joints,' he advises. 'Many of these cracks only appear once the weather warms. A slow drip can turn into a full break a few weeks later. ABS and PVC are even more vulnerable, and the repairs can get expensive once cabinets, walls, or flooring need to be opened.
'The other issue in winter is grease. Boiling water moves the grease only a short distance before it hits a cold section of pipe and hardens again. If food waste is in the mix, the grease acts like glue, trapping it in place. The clog becomes tighter and harder to clear,' only adding to the reasons your sink won't drain, rather than clearing any blockages.
What to Do Instead
There are plenty of more effective alternatives.
This winter, skip the chemicals and skip the kettle if you need to fix a clogged kitchen sink, says Devin.
Instead, he shares:
- 'FOG (fats, oils, and grease) is the enemy. Don't put it down the drain in the first place. Wipe pans with paper towels, compost scraps.' We recommend using the bestselling ENLOY Compost Bin available at Walmart for this, which features an odor-proof design
- 'Use a plunger for minor clogs. Every homeowner should have a drain plunger with a flexible flange to seat around pipe openings. The Korky BeehiveMAX Heavy Duty Toilet Plunger on Amazon seems to work well and costs less than $16.'
- 'Try a hand-crank drain snake for bathroom sink and tub clogs. Hand crankers are available from most plumbing companies, and the Drainsoon Drain Auger 25 Ft available at Amazon is a good generic snake you can buy yourself.'
- 'If you get to a certain point in the winter and you have gurgling drains or slow drains everywhere, the correct solution is to get the house hydro-jetted, using cold water.' You may need to call in a pro for this. 'Hydro-jetting uses high-pressure cold water to clear grease and roots out of main house sewer lines,' continues Devin. 'It costs about as much as a snake but is much more effective and less likely to cause damage to pipes than the thermal shock of pouring boiling water down them.'
Additionally, says Josh, 'Use dish soap and hot tap water, not boiling water, right after cooking. Let it run for 30 to 60 seconds to help keep grease suspended.' For this, we recommend using Dawn Ultra Liquid Dish Soap, available at Walmart.
'If the clog still will not move, call a plumber. It costs less than repairing a cracked drain line inside a wall. If the pipe froze and thawed recently, avoid hot water for a while. Let it warm up with room heat, or pour warm water slowly over time.'
And finally, knowing the perfect temperature to run your heating to avoid frozen pipes and when to drip faucets will prevent frozen pipes, and therefore negate the risk of bursts.
What to Shop
All prices were correct at the time of publication.
For tough clogs, this plunger clears blockages fast, forcing eight times the volume of air down your drains compared to a regular plunger.
This drain snake includes an easy-to-use handle that spins 360 degrees, and is easy to use with a universal fit.
This sink strainer stops food from flowing down pipes and clogging up your drains, and won't scratch your sink.
We always recommend wearing gloves when tackling cleaning or unclogging drains. These are durable, reusable, and tear-resistant.
This ultra-concentrated formula is safe for showers, sinks, tubs, pipes, and can be used to help prevent clogs from forming, too.
Clear clogs like a pro with this easy-to-use drain snake, which features an ergonomic pistol grip and a flexible spring that effectively bends without breaking.
Meet the Experts
Devin is the founder and CEO of Mountain Standard Plumbing, which is based in Denver. He has more than a decade of experience and provides comprehensive plumbing services to Colorado homeowners, from routine maintenance to emergency plumbing and sewer services.
As the founder of AirConditionerLab, Josh is an expert when it comes to all things plumbing, heating, ventilation, and cooling. He set up his website in 2014, publishing his findings to help readers solve their HVAC problems.
'Boiling water works on glass and metal, but it is not safe for plastic pipes in a cold house,' adds Josh. 'It sounds like a good idea, but winter temperatures change how the plumbing reacts,' which is why it's also vital to insulate your pipes properly.
