> How long do you sit in a bath?

Another Japan resident here! It is common for a family to share a bath for the evening. (One at a time!) This works because each person showers to get clean before you get in the bath. Many also have folding bath covers, which help to avoid the water from cooling down and to keep the water clean during the showers. Still, nobody wants to be last.

> My immediate reaction to this is, “there’s a way for my house to be remotely flooded”.

A smart reaction! But most baths are also whole-room units, with a floor drain, and are intended to get wet. I myself have forgotten to stop the bath water a number of times (neither I nor my bath are so "smart") and while it is an unfortunate waste of water, there is no danger of flooding, only slight embarrassment.

A Japanese bath sounds a lot more like what Americans call a hot tub.

BTW, Japanese bathing is somewhat visible in My Neighbor Totoro, a really cute movie.

If you look at a picture of one, they're basically tiny hot tubs.

In most ways, yes. E.g. you clean yourself before you get in, so the water remains relatively clean after a few people. Unlike a hot tub though it's drained between uses, so it doesn't really have some of the nastier issues that hot tubs can acquire (nor does it need higher chlorine content to mitigate it).

> (One at a time!)

That's unexpected.

> A smart reaction! But most baths are also whole-room units, with a floor drain

Nice concept! Do you have any problems with mold build up?

Not a resident but I have friends there and stayed in a bunch of different apartments.

Bath rooms in smaller apartments, and also in hotels, tend to be, literally, whole-room plastic/resin structures, so it dries easier and if mold appears it's in the plastic surface and easy to get rid of it.

I have a friend with a very big fancy apartment, and his huge bath room is covered mostly in tile and has very good ventilation. The bath even has a waterproof TV so you can watch a movie meanwhile!

It's 98% humidity for months, you need to worry about the whole house!

Are you sure about that number?

I live in famously hot and humid Singapore, and it's usually around 70% to 80% humidity here during the day. I find it hard to believe Japan is even muggier?

I just randomly checked the weather for Osaka and Tokyo (on Google) and they have about 60% to 70% at the moment.

No, I exaggerated slightly; but we're past the wettest season now AFAIK.

These rooms have ventilation (and also usually a heater, cooling, dry mode). The ventilation can be set to 24/7 mode, which runs at a low setting, always on. Japanese houses/apartments also typically have a house ventilation system, meant to run when it's humid. Mold in general is a problem here, so ventilation is incorporated well.

It's fun in the winter when you're running humidifiers but forget to turn off your house ventilation and don't understand why you're still so dry.

> Japanese houses/apartments also typically have a house ventilation system, meant to run when it's humid.

Do they have Mechanical Ventilation and Heat Recovery (MVHR) or is this more like Aircon? I've recently moved somewhere more humid and I'm looking to get a grip on what other countries do.

From what I can tell it's a just a house fan. The house ventilation doesn't do heating, cooling, etc. It just moves air.

Unfortunately, it does build up from time to time, yes. However, there is another feature to most bathroom units, which is the room drying feature. It sends warm dry air into the bathroom to dry it. It is also a great tool for the 6 months of the year in which drying clothes outside is impossible. Even so, the appearance of mold can feel inevitable!

> How long do you sit in a bath?

80kg of meat can hold a lot of heat. It cools quicker than you think it would. Also, Japanese families often share the bathwater within themselves(but everyone showers outside the tub first), and the water will become lukewarm at some point in that use case.

> My immediate reaction to this is, “there’s a way for my house to be remotely flooded”.

Yep, remotely operating a machinery will always have some risks. Every machinery should have someone with an emergency stop button should be monitoring it at all time, ideally. But it's a well engineered tub auto-fill in the shower room, it effectively belongs to "inherently safe" category of equipment.

Do you have a water drain in your bathroom floor?

This is uncommon in the US, so a bath overflow quickly becomes a significant structural issue.

But USA bath tubs have overflows (redirecting water into the drain if the taps are left on), surely?

In the US, any tub made past about 1900 or so has an overflow drain that prevents overfilling. The adoption of such drains not quite contemporaneous with the adoption of indoor plumbing, but very soon after.

It's the metal plate usually just below the faucet that looks like it might be useless. But it has an opening underneath to let the overflow water in. These are always sized to handle more water than the faucet can output.

This is basically a non-concern in anything but very, very old, unremodeled bathrooms.

The sinks do as well, but it is more obvious.

Im not sure about bathtubs, but in the U.S. it's apparently legal to sell lavatory sinks without an overflow. Ask me how I know.

This puzzled me and I looked it up, and yes, sinks without overflow meet code [1] (but not tubs). So your situation was apparently legal.

But the sibling comment to this one, where a sink had an overflow, but it was not connected, did not meet code [also 1].

Go figure. There must be some reasoning there, but I'm confused as to what it is.

https://forms.iapmo.org/email_marketing/codespotlight/2018/m...

Code sometimes makes allowances for situations which aren't ideal, as long as they aren't deceptive or creating a false sense of security.

So if you have old two-prong outlets in your house from back when, those are allowed.

If you replace them with a three-pronged outlet which is ungrounded, that breaks code.

If the three-pronged outlet is a GFCI outlet labeled with NO ELECTRICAL GROUND, that is allowed.

My last apartment had the overflow drain hole but it wasn't attached to anything. The water just went directly into the wooden cabinet underneath. Madness. Literally worse than not having the hole because it reduced the capacity of the sink. This is what happens when landlords who DGAF hire handymen who DGAF to do all the work on their units.

To be fair to the potential handyman or contractor many overflow drains are integrated into the sink drain before they attach anything. It might have been the landlord buying temu style sinks with fake overflow holes.

Many overflow drains are not or are poorly connected. If you buy a new home, the inspector will usually skip to overflow test because it will likely fail.

Well, it's also legal to sell food that tastes bad. Doesn't mean you should buy it.

The tub sits in a big shower booth. Other bathroom amenities like sink and washing machines are installed outside the booth. Toilet is usually a separate room entirely. So no problem overflowing water onto the floor since that's how you take a shower.

Bathroom floor drain is common (might even be a code requirement?) in commercial buildings but not in homes.

All my tubs and sinks in the bathrooms have an 'overflow drain' near the top which you are unable to fill beyond. Is there any reason why that wouldn't be sufficient?

Yeah, if the drain in the sink is clogged. US bathroom pipe is 1.25" which will (probably) lead to a 2" and 4" pipe eventually (depending on when, where, and how your house was built ofc). The hole in the sink leads to the same initial pipe.

It makes the tub taller than it is deep by a little bit and doesn't look as nice are the only reason I can think of. A little bit of splashed water just isn't a big deal in most wet bathroom setups. They could also just put a drain right off the side of the tub.

My Japanese style bathroom here both has an overflow in the tub and a drain in the middle of the room.

In Japan it's very common for bathrooms to be wet rooms; likewise South Korea and Taiwan among others.

To add to this, it's so nice. Sit on a stool in the middle of the room and rinse, soap up, scrub to exfoliate, rinse, then roll the lid of the bath open and soak in a sub much deeper than an American one. Bath is programmable to maintain a constant temperature.

Basically a spa experience every day.

I wish more people knew how nice it is! And the toilet is in a completely separate room so there's no contention among one person who wants to take a bath and another who needs to use the toilet.

I just wish dish washers and dryers were more common in Japanese households. I'm in Okinawa where dryers are a lot more "standard", but dish washers are relatively rare.

I believe it’s mandatory in Australia

Yes, I can't remember seeing a bathroom or laundry here that didn't have a floor drain. Seems insane for that to not be standardised. I briefly lived with a bathroom in the UK that was carpeted?!

i briefly lived in a house that had second floor laundry with no tray or floor drain. the first day after installing a new washing machine it flooded and did over 30k damage to carpet, drywall, and installed electrical. Insurance would not cover installing a floor drain or tray, and the owner chose to let that decision stand.

truly bizarre

Considering that US houses usually either have a crawl space, basement, or are on a slab the lack of a drain is weird when you think about it. You would think wet locations would be required to have a drain.

I think a lot of European houses have floor drains in the bath, you can basically hose the bathroom down.

More on topic. Outside of the US R290 (propane) heat pumps are common. But illegal in the US because the refrigerant manufacturers control the code bodies. You can have a 20lb propane tank hanging off a BBQ which in normal operation is literally on fire. But you can't have an R290 monoblack cause it's too dangerous.

> I think a lot of European houses have floor drains in the bath, you can basically hose the bathroom down.

Weirdly, in the UK it's common to have carpet in the bathrooms.

> How long do you sit in a bath?

I'm an American and my answer is at least an hour, maybe more, depending on how I'm feeling. I usually listen to an audiobook. Baths are for hanging out and relaxing in.

Reading this comment from an hot european bathtub right now, I've been here for two hours

Don't you get all wrinkly?

I don't mind

https://en.wikipedia.org/wiki/Wrinkle#Water-immersion_wrinkl...

If I'm in the bath I'm either reading a good book, or talking with my wife (I have a tub big enough for two - takes a lot of water to fill) - either way I'm going to be in it for an hour or two. As the other poster said, if I want to get clean I'll take a quick shower. The tub is nice when my muscles get sore and tight from work.

> or talking with my wife (I have a tub big enough for two - takes a lot of water to fill)

Taking your wife into the tub with you is just good economics then. Saves on water necessary to fill the thing p.

> How long do you sit in a bath?

We love our baths here in Japan

> My immediate reaction to this is, “there’s a way for my house to be remotely flooded”.

I forgot to mention that it senses and automatically stops filling the bath at a select number of liters, even if you start a bath using the physical button when you're at home.

> How long do you sit in a bath?

The entire point of a bath is to relax and soak in it. Otherwise I'd just take a far more economical shower.

Interesting that that's a feature of the water heater and not the tub. It has to travel through the plumbing all the way round-trip to the heater? You must have isolated recirculation plumbing to deal with the grey water, yeah?

Typically Japanese homes are laid out economically so the bath is right where the hot water heater is. In our house from the 70's it's probably not more than meter through the wall to the water heater. Even in apartment buildings, typically each apartment has it's own tankless gas water heater on the outside wall of the building so it's easy to meter usage separately.

That is what I always see in wet saunas/bathrooms around me. The bathing room is a main feature so things like main plumbing and water heaters are all placed around that to keep it simple. Recirculation additions after that would then be two simple connections off the back of the tub, probably near where the faucet goes.

Technically, you could also just pull refrigerant lines from the heat pump to the bath tub - you probably already run those to the indoor AC units you have in different rooms anyway - or connect the bath tub to the hot water lines you run to the radiators. Both imply a grey water heat exchanger built into the tub.

Depends on setup, of course. If there's a central AC blowing hot/cold air through ducts, you're stuck using a grey water loop. But it is the least attractive setup...

Barring some catastrophic overflow clogging + drain clogging or other issue, your house will be fine! Your wallet may not be.

These are truly _bath_ rooms. The shower and bath are side by side, with the intent that you wash off before hopping into the bath to soak. Thus if the tub overflowed it would just go down the shower drain.

Most baths (in the UK at least) have overflows right so the primary risk is just wasting a lot of water?

If you have a delayed start dishwasher or washing machine, you already have that.

While in the US making a bathroom a "wet room" is rare, it can be quite common in other countries.

You can totally remodel bathrooms to be "wet rooms" in the US, it is well worth it.

Kids flooding the bathroom via the tub? Not a problem. Toilet overflowing? Gross, but not a problem.

I wish I would have made all the bathrooms in my home wet rooms.

This was my biggest takeaway from Japan in terms of home design - the bathroom design. At a small apartment in Tokyo the "bathroom" was in fact three separate spaces: a nook where the washer and sink lived which opened into the living room, one side of the nook featured the toilet closet, the other, and actual bathroom with tub and shower. This lets three people use the plumbing fixtures - toilet, shower/bath and sink. Though not all of the places I stayed at split the sink and bathroom.

Contrast this with the all-in-one design where a person taking a shower monopolizes all the plumbing fixtures even while they are not using them. I was on a bachelor party trip with 8 guys and two bathrooms where some inconsiderate people camped out in the shower for 20 minutes while people waking up had to pee so badly they went outside in the bushes. Meanwhile on a trip to Japan with five people we could easily share one or two split bathrooms and never had an issue.

Oh, and the electric bidet is a clear winner in terms of bathroom accessory to buy. Less TP use and no threat of swamp ass that demands you take a shower. Heated seat in winter is a blessing, especially in the morning. After my Japan trip it was the first thing I bought when I got back home.

Not OP but I used to sit in a bath for a long time reading, gradually adding the hottest water to keep it at a nice temp. It's been a while tho, but I'm sure there's someone like me out there :)

Every bathtub I've met has an overflow drain near the top, although maybe that drain is smaller then the output of my faucet, good thing mine isn't connected to the internet :D, YMMV.