Q: When it’s really cold outside — in the 20s or lower — the toilet tank in my powder room develops so much condensation that it drips onto the floor in a measurable amount. The condensation forms only on the side of the tank that’s connected to the water line, which runs in an insulated cavity along a joist from where water comes into the basement. The other side of the tank, adjacent to the vanity, remains dry. The toilet is on an outside wall on the main floor, above the unfinished part of my basement. What can I do to prevent this from happening? Would wrapping the water line with insulating tape work?
A: When condensation forms on the outside of a toilet tank, it’s because the tank is cold — typically because the incoming water is cold — and the air nearby is warm. Warm air holds more moisture, so when it hits that cold surface, some of its moisture goes from being invisible water vapor to the liquid water dripping on the floor.
Condensation on toilet tanks is a fairly common problem. One cause is often steamy air from showers. Better ventilation and shorter, not-quite-so-hot showers can reduce the humidity in the room, which in turn reduces the condensation. But powder rooms don’t typically have showers.
In homes with older toilets, installing a new, water-efficient toilet sometimes helps because these toilets don’t usually empty the whole tank on each flush. The toilets stay warmer because some water in the tank is at room temperature — unless the bathroom is so busy that the toilet often gets flushed repeatedly. If your powder room is used only occasionally and if the toilet isn’t a water-efficient model, replacing it would be one thing to try.
If you do opt for a new toilet, consider getting one with an insulated, or lined, tank. The insulation, often Styrofoam, keeps the water temperature in the tank from dictating the temperature of the outside surface. That surface stays warmer, so condensation is less likely. Or you can choose a pressure-assist toilet, which contains the flush water inside a separate pressure vessel in the toilet tank. Water in a house is pressurized, and these toilets use that to compress air within the pressure vessel, resulting in added flushing power. A side benefit is that condensation is less likely because the vessel is within the tank.
If you’re replacing the toilet, make sure the new model works well, independent of the insulation or pressure issues. A water-saving toilet doesn’t save water, and it might not even reduce the condensation problem, if you have to flush repeatedly. Maximum Performance testing (MaP) is a voluntary rating system that grew out of consumer frustration with some 1990s water-saving toilets that performed miserably. The program scores toilets by the amount of solid waste (soybean paste and toilet paper) they can dispose of with a single flush.
Publishing the results has encouraged manufacturers to make better toilets. By 2017, the average tested toilet could eliminate twice as much waste as the average in 2003, when the first ratings were published. From the program’s website, you can download the list of tested toilets or choose a list limited to models that also meet water-thrifty standards set by WaterSense, a program of the federal Environmental Protection Agency. The list notes models that have an insulated tank or a pressure-assist design and includes practical details such as the rough-in distance, which helps you pick a model that won’t require a lot of remodeling to install. The MaP program’s online guide, titled, “Consumers — 15 Important Tips Before You Purchase a Toilet,” explains the rough-in distance and other factors to consider.
Another possible solution for a condensation problem is to install a mixing valve so some of the water going into the toilet tank comes from a hot-water pipe. You’d need to hire a plumber and perhaps other tradespeople, depending on how handy you are and how easy it is to open up a wall to tap into a hot water pipe and install the valve. Having a persistently damp floor in a bathroom can eventually rot out the floor and lead to very costly repairs. So perhaps the cost of installing the valve, patching the walls and paying the ongoing cost of heating the water might make sense from a financial viewpoint. But it seems incredibly wasteful in terms of energy use unless you rig up handles and turn on the hot water only when the weather is frigid.
You ask whether wrapping insulating tape around the water line leading to the toilet would make a difference. The water line is already in an insulated cavity, which should be keeping it about the same temperature as it was while traveling underground to your home. The water is cold. Wrapping the pipe with insulating tape would not make the water warmer, which is what would minimize the risk of condensation.
Electric heat cable, designed to keep cold-water pipes from freezing, might seem to be a better solution. But ground water in Virginia is on average in the md-50s, which is too warm for heat cables to make a difference unless your basement gets so cold that the water cools while traveling through it. Heat cables made by Frost King, a popular brand, have thermostats that turn on heat when pipes are below 38 degrees and switch off above 45 degrees.
Because the condensation is on only one side of the tank, you might want to investigate whether there is an insulation issue with your house that is contributing to the condensation. A home inspector with a thermal-imaging camera can check the wall, floor and ceiling to pinpoint gaps.
Have a problem in your home? Send questions to localliving@washpost.com. Put “How To” in the subject line, tell us where you live and try to include a photo.
Source link: https://www.washingtonpost.com/home/2024/03/29/how-to-stop-toilet-condensation/