Quick Answer: How Did Chinese Courtyards Drain Rainwater?
Traditional Chinese courtyards can drain rain through a connected route from roof slopes to paving, channels and outlets. Some parts, such as an eave or an open gutter, are visible. Others run under paving or walls.[1][2][3]
- Catchment: Roofs guide water to the eaves, and graded surfaces can direct it after it lands.[1][3]
- Palace example: At the Forbidden City’s three main halls, carved dragon-head spouts (螭首, chīshǒu) discharge water from the terraces.[1][3]
- Residential example: Huizhou houses can bring roof runoff into a skywell (天井, tiānjǐng) and then carry it away in a concealed drain.[4][5]
To read a courtyard, follow where the water lands, where it enters a channel and where it finally leaves the enclosed space.[1][2][4]
A line of drops falls from the eaves. On the ground, a shallow stone groove sends the water toward a small opening. What looks like an isolated feature can belong to a route that continues below the paving.[1][3]
Following Rain from Eaves to Outlet
Start at the roof edge. Chinese drip tiles help direct runoff from particular rows of roof tiles. Once the water lands, the slope of paving or the shape of a stone channel can guide it toward an inlet. A low groove alongside a building may carry water to an opening under a step or wall.[1][3]
Water may enter a covered drain through a perforated stone, then continue along a route invisible at the surface. In the Forbidden City, a documented type of inlet uses a stone cover pierced in a pattern resembling an old coin. The opening is the visible entry to the drain. In a timber building, the base under a post also keeps the end of the wood away from direct contact with the ground. The column base and the courtyard drain are separate features that address moisture at different points.[1][2][3]
In a photograph, a visible water channel tells you the direction of one stretch. The destination may require a site plan or a conservation record. This is especially true when the inlet disappears under a wall or paving.[2][3]
The Forbidden City’s Terraces and Drains
A Palace Museum account describes the drainage of the three-tier terrace beneath the Hall of Supreme Harmony, Hall of Central Harmony and Hall of Preserving Harmony. It records 1,142 carved outlets around the shared terraces. The channels and gently sloped surfaces guide runoff to openings at the edges. The dragon-head forms then carry water outward through holes bored through the stone.[1][3]
Beyond the terrace, open and covered drains connect the courts to the Inner Golden Water River. That river receives runoff from many parts of the palace through a wider network. Palace Museum research notes that the network has been altered and repaired over time. In 2023, reporting from the museum identified sediment and litter blocking a connection near the Palace of Compassion and Tranquillity, where water briefly collected. That blockage interrupted the route between the surface and the buried network.[1][2][6]
Why Huizhou Skywells Bring Water Inward
Huangshan’s local history office records an inward-draining arrangement in traditional Huizhou houses. A skywell brings light and air to the interior. Nearby roofs can slope toward that opening and send water into the small courtyard, where a channel carries it into a covered drain.[4][5]
The expression four waters return to the hall (四水归堂, sì shuǐ guī táng) describes that inward collection and has an association with keeping prosperity within the household. The household saying concerns the inward flow at roof level. At ground level, the channel conducts the water away. The skywell and the stepped fire walls around a Huizhou building do different work within the same compact arrangement.[4][5]
FAQs About Chinese Courtyard Drainage
Do the Forbidden City’s carved dragon heads drain water?
The documented spouts around the three main halls have openings through the stone. They discharge water from the terrace edges and also form part of the carved decoration.[1][3]
Does an inward-sloping roof leave water inside the house?
In the Huizhou arrangement described by Huangshan’s local records, rain enters the open skywell. A channel then takes it into a concealed drain.[4][5]
Can you see the entire drain from the courtyard?
You can often see eaves, grooves and inlets. Covered drains and their connections may only be visible during survey, maintenance or excavation.[2][3][6]
Sources
[1] An Na, Palace Museum. Drainage design in classical imperial palaces and gardens
[2] Palace Museum. The formation and function of the Forbidden City’s Ming drainage network
[3] Hunan University School of Architecture and Planning. Rainwater routes and drainage features in historic buildings
[4] Huangshan Local History Office. Traditional Huizhou houses and their skywells
[5] Buildings. Research on the shape and environment of Huizhou skywells
[6] Beijing News. Reporting on Palace Museum drainage during heavy rain in 2023