Rooms · Wash · 13 min read · Updated September 2026

The bathroom

The room the classical house did not have, and the privy it did. What the yang-house manuals said about the latrine, what the twentieth century made of the bathroom when it arrived, which of its rules are old and which are recent, where the room goes on a plan and over what, the water seal the tradition never knew it was describing, and what the building science says about damp, air and the same room.

Oriented N 341°

Water

Fig. 01 A bath beside a window. The tradition’s whole demand of the room is that it be closed, dry and out of the way; the window does most of that.

For almost all of its history the tradition had nothing to say about bathrooms, because houses did not contain them. Water came from a well or a river, washing happened in a basin, and the privy stood in a corner of the yard. What the manuals did discuss was the privy, and what they said about it is the root of everything the modern books say about the bathroom. The rules that now fill a chapter of every feng shui manual are twentieth-century work, practitioners applying an old vocabulary to a new room, and they are worth reading in that light. Some of them are good. Some of them are the plumber’s rules in another language.

The privy, in the old manuals

The yang-house manuals of the Ming and Qing knew one wet room, the latrine, and treated it as the house’s most unclean place: to be kept away from the stove, away from the gate, away from the ancestral hall, and out of sight. The Eight Mansions method gave the rule a compass form that is still taught. Of the eight directions from the centre of a house, four are favourable to its owner and four are not, and the method puts the things that must be borne but not honoured, the privy, the rubbish, the stove’s fire-mouth, in the unfavourable four, so that they press down on the bad directions rather than spoiling the good ones. Wong and Skinner both describe the placement; Too repeats it as the rule that a toilet must not sit in one’s best sector. Japanese kasō, the house physiognomy that grew from the same roots, has the version most people have heard: no toilet, kitchen or entrance at the north-east, the demon gate.

What the tradition made of the bathroom

When piped water and the water closet arrived, the manuals had a new room and an old vocabulary. The bathroom is Water, in the Five Element reading, and its defining feature for the tradition is that water leaves through it. Drains, in the manuals, are where qi goes; the room is read as a place of loss and of yin, damp, dark and private, and the rules follow from wanting to contain both. Rossbach records the Black Sect version of the 1980s, Wong the compass version of the 1990s, and Too the popular synthesis, and they agree more than they differ.

Plan 01 The bathroom: fittings out of the door’s line, a window to vent it, a door that closes The door opens at the bottom. The toilet sits on the side wall, out of the line of the door (solid); the ghosted position directly opposite the door is the one every school and every plumber dislikes. The window on the far wall carries the moisture out. What the tradition asks of the room is mostly that it be closed and dry.

Position on the plan

The one bathroom rule with a classical shape is about the centre. The tradition wants the middle of a house open, stable and Earth; a bathroom there is read as water at the heart of the plan, and it is also, in practice, a windowless room that must be mechanically ventilated and drained through a long run of pipe. A bathroom on an outside wall with a window is what every school and every architect prefers, for reasons that do not need to agree.

Fig. 02 Two storeys cut through. Below, a kitchen with its stove, a hall with the front door, and a bedroom with the bed’s head against the party wall. Above, the bathroom drawn solid where the tradition puts it, over the hall, with its pipes gathered in one duct; and ghosted in the three places the manuals refuse: over the bed’s head, over the stove, and over the front door. The rule is a rule about what is overhead. A sleeper under a cistern, a stove under a drain and a threshold under a toilet are the three stacks every manual names; the plumber’s reason for the solid version is that the pipes are shortest and the noise is furthest from the bed.

The other position rule is vertical, and it is the one that matters in a house on two floors. The manuals refuse a bathroom over a bed, over a stove and over the front door, and they refuse it at the middle of the plan for the reason above. What they accept is the bathroom over the hall or the landing, which is where a plumber would put it too: the soil pipe and the water supply run together in one duct, the runs are short and fall steeply, and the sound of a cistern refilling at three in the morning is a wall and a corridor away from anyone asleep. A bathroom over a bedroom puts that sound, and the risk of a leak, directly over a sleeper; a bathroom over the kitchen puts the leak over the food. The tradition’s objection and the surveyor’s are the same objection.

The door, and what it faces

A bathroom door that opens onto the front door, the bed or the kitchen is disliked by every manual: the tradition reads it as the house’s most private and wettest room exposed to its most public or its hottest. The remedies are to keep the door closed, to hang it so that it swings toward the wall rather than the room, and, where a bathroom must open off a bedroom, to treat the door as part of the wall: the same colour as the wall, no glazing, and closed at night.

The en-suite is the case the manuals did not foresee and now spend most of their bathroom pages on. A door in the bedroom wall that faces the bed shows the sleeper, from the pillow, the toilet; the same door on the side wall, or at the foot of the room with the bed turned from it, shows nothing. Where the plan is fixed, a curtain across the opening, a door that closes itself, and a light in the bathroom that comes on low at night do what the tradition asks. The site’s bedroom pages draw the bed away from such a door for the same reason they draw it away from the room door.

The drain, and the water seal

The manuals’ anxiety about drains, that qi leaves by them and the plug should be in and the lid down, has a modern reading the manuals did not intend. Every drain in a modern bathroom carries a trap, a U-bend that holds a few centimetres of water, and that water is the seal between the room and the sewer. A trap that dries out, in a shower that is not used for a month or a basin in a guest room, lets the gases of the drain into the house, and the smell that follows is what the older tradition would have called the privy arriving in the room. Keeping the seals full, running water into unused drains, fitting lids and covers, and keeping the door closed against the rest of the house are the tradition’s rules and the plumber’s rules at once. The site does not claim that the manuals knew this. It notes that the practice they arrived at is the practice that works.

Fig. 03 The same waste twice, cut through at the trap. On the left the fitting is in use: a few centimetres of water stand in the bend, held there because the outlet leaves above the bottom of the U, and that water is the whole of the seal between the room and the sewer. On the right the same trap after a shower nobody has used for a month, or a basin in a spare room: the water has evaporated, the bore is open end to end, and what the old manuals called the privy arriving in the room comes up the pipe. The remedy is the one the tradition already gives for its own reasons — run water into every drain, keep the plug in, the lid down and the door shut. The manuals' anxiety about drains is about qi leaving by them, not about what comes back; the site does not claim the manuals knew about traps, only that the practice they arrived at is the practice that works. A domestic trap holds about fifty millimetres of water. The drawing is a section, not to scale, and shows one fitting: a floor gully, a shower and a washing machine standpipe all carry the same seal and all dry out the same way.

Dry, and why

The numbers are worth having. A bath or a shower puts a litre or more of water into the air of a small room, and the air of a bathroom after a shower is close to saturated; on a cold wall or a cold window that moisture condenses, and mould grows where surfaces stay wet. The English building regulations ask a bathroom for an intermittent extract of about fifteen litres of air a second, roughly one small fan, or an openable window; the kitchen gets more, the bedrooms get a trickle. A fan on a timer that runs for twenty minutes after the light goes off, a window opened after a bath, and a heated room in winter so that the walls are not cold are what keeps the room within the guideline. The tradition’s vocabulary for all of this is one word, dry, and it is the right word.

Inside the room

Within the bathroom the tradition’s vocabulary is Water and Metal: white, pale grey, glass, tile, chrome, the round basin. It asks for a little Earth or Wood to steady them, a wooden stool or bath rack, a plant that tolerates steam, a fern or a pothos, a warm towel, a stone dish, and it dislikes the mirror that faces the door, which shows the room to whoever opens it and sends the door back at whoever is inside. Beyond that it has little to say, and the designer has more: a window that opens, a floor that drains, a light that is warm rather than clinical and, for the night, low, since the sleep research finds the bright bathroom light at two in the morning as waking as any screen; a door that closes properly and a lock that works; and storage that keeps the surfaces clear, because a bathroom with nothing on its surfaces dries faster and reads as clean before it is cleaned.

Reading the bathroom

The tests, in the order the tradition would make them:

Where is it on the plan? On an outside wall with a window, not at the centre. If it is at the centre, the fan and the door do the window’s work and must be good.
What is it over, and what is under it? A hall, a landing, another bathroom: yes. A bed, a stove, the front door: no, and if it cannot move, the leak protection and the sound insulation below it must be real.
What does the door face? Not the front door, not the bed, not the stove. Where it must, the door is part of the wall, closed, and swings toward the wall.
Does it dry? A window or a fan that runs after use, a heated room in winter, no condensation on the glass an hour after a shower.
Are the seals full? Water in every trap, covers on the drains, the lid down, the door closed.
Where is the mirror? Not facing the door. Beside the basin, lit from both sides, is where a mirror is used.
What is the light? Warm by day, low by night, and the switch where a hand finds it in the dark.
What is on the surfaces? As little as possible. The room the tradition wants is the room that is no trouble, and a clear surface is most of that.

Keep it that way and the room will do what the tradition asks, which is to be forgotten, and what the building science asks, which is to be dry.