Rental homes in Japan often come with bath and toilet features that aren't common in many other countries — bathtubs with a reheating function, toilets with a washlet (a warm-water washing function), and 24-hour ventilation systems, among others. Using them without knowing how they work can sometimes lead to unexpected malfunctions or trouble, so it's worth getting familiar with the basics. Since the bathroom and toilet are places you use every single day, knowing the correct way to use them makes it easier to avoid unnecessary problems.
- The reheating function lets you reheat the bathwater with a single switch, and it's designed on the assumption of heating enough water for the whole family in one go.
- A washlet is a warm-water washing function, and you can adjust the water temperature and pressure using the remote control.
- Keeping the ventilation fan running for a while after you bathe makes it easier to prevent mold and moisture buildup.
- The 24-hour ventilation system is a mechanism for circulating the air in your rooms, and it serves a different purpose than the bathroom's ventilation fan.
- Knowing which paper products can be flushed and which can't helps you avoid clogging the toilet.
How to Use the Reheating Function, and What to Watch Out For
The reheating function (oidaki) is used when the water you've drawn in the tub has been sitting for a while and has gone lukewarm. With a single switch on the control panel, it circulates the water through the pipes and reheats it. Because the system is designed around heating enough water for a family or housemates in one go, if you're living alone and are concerned about utility costs, it's worth considering just taking a shower instead rather than using the reheating function every time. How it operates differs by model, so it's reassuring to check the instruction manual that comes with the unit. It's also worth knowing that the system detects the water level in the tub while reheating, so it may not work properly if the water level is extremely low.
The Bathroom Ventilation Fan and Preventing Mold
Humidity in the bathroom rises sharply right after you bathe, so it's important to run the ventilation fan to clear that moisture out properly. Keeping it running for about 30 minutes to an hour, not just right after use, makes it easier to prevent mold from forming on the walls and ceiling. In units with a bathroom dryer function, you can also use it to dry laundry on rainy days. We cover moisture-control habits in more detail in a separate article. During seasons when humidity tends to run high, such as the rainy season (tsuyu) or winter, making a habit of running the fan a bit longer than usual helps prevent mold more effectively.
How to Use a Washlet (Warm-Water Washing Toilet Seat)
Toilets in many Japanese homes are fitted with a washlet — a seat with a warm-water washing function. Some models automatically warm the seat when you sit down, and let you fine-tune the water pressure and temperature using the remote control. If you're using one for the first time, it's a good idea to try the weaker pressure setting first. Checking where the stop button is ahead of time will put your mind at ease if you're ever unsure how to operate it. In winter, using the seat's heating function together with it can also take the chill off when you sit down.
What Can and Can't Be Flushed Down the Toilet
Toilets in Japan are designed around toilet paper that dissolves easily in water. Items that don't dissolve well, such as facial tissue or cleaning wipes, can cause clogs if flushed, so be sure to throw those in a dedicated trash bin instead. If the toilet does get clogged, avoid repeatedly trying to flush it and instead contact the management company promptly. Households with small children may find it reassuring to double-check as a family that things like diapers, which can't be flushed, don't get flushed by mistake.
How This Differs from the 24-Hour Ventilation System
Separate from the bathroom's ventilation fan, most homes are also fitted with a 24-hour ventilation system that continuously circulates the air throughout the living space. Installing this system is legally required, and it's designed to run at all times, with only a small impact on electricity costs. Its performance drops if dust builds up in the filter, so make a habit of cleaning it regularly. We also cover how to use housing equipment in general in a separate article. Since the condition of the filter may be checked when you move out, staying on top of routine upkeep gives you peace of mind.
Frequently Asked Questions
Do I have to use the reheating function every time?
No, it's fine not to use it. If you're living alone and the amount of hot water is a concern, taking just a shower is also an option.
The washlet water feels cold — is it broken?
It may be a type that isn't connected to the water heater, or the temperature setting may simply be low. Check the settings on the remote control, and if that doesn't fix it, contact the management company.
What should I do if the toilet gets clogged?
Avoid repeatedly flushing, refrain from using the toilet, and contact the management company or landlord promptly.
Summary
The reheating function, washlets, and 24-hour ventilation systems are features unique to Japanese homes. Knowing the basics of how to use them, along with the points to watch out for, lets you use them comfortably and with peace of mind. If something is unclear, avoid guessing on your own — check the instruction manual or consult the management company instead. Getting into the habit of reaching out early when you run into trouble, rather than handling it alone, will give you peace of mind.