Pour-flush Toilet

Just like a cistern flush toilet, the pour flush toilet has a water seal that prevents odours and flies from coming back up the pipe. Water is poured into the bowl to flush the toilet of excreta; approximately 2 to 3 L is usually sufficient. The quantity of water and the force of the water (pouring from a height often helps) must be sufficient to move the excreta up and over the curved water seal.

Both pedestals and squatting pans can be used in the pour flush mode. Due to demand, local manufacturers have become increasingly efficient at mass-producing affordable pour flush toilets and pans.  

The water seal at the bottom of the pour flush toilet or pan should have a slope of at least 25°. Water seals should be made out of plastic or ceramic to prevent clogs and to make cleaning easier (concrete may clog more easily if it is rough or textured). The S-shape of the water seal determines how much water is needed for flushing. The optimal depth of the water seal head is approximately 2 cm to minimize the water required to flush the excreta. The trap should be approximately 7 cm in diameter. Pour-flush pans can be connected to twin-pit for pour-flush latrines, a pre-treatment and treatment units such as septic tanks, biogas settlers, anaerobic baffled reactors, toilet-linked biogas plants etc. or a small-bore or solids-free sewer or conventional sewer system. The collection system on its turn has to be connected to an appropriate treatment system.

The superstructure’s primary function is to provide privacy and protection to the user from the natural elements. The costs for the superstructure vary depending upon the kind and type of construction technique and material used (e.g. bamboo, mud, bricks, cement blocks, woven palm fronds, etc.). Construction of a temporary superstructure, which can be replaced afterwards with a permanent one, may be considered.

The pour flush toilet (or squatting pan) prevents users from seeing or smelling the excreta of previous users. Thus, it is generally well accepted. Provided that the water seal is working well, there should be almost no odours and the toilet should be clean and comfortable to use. Pour-flush toilet pans are most commonly used in combination with a single- or twin pit pour flush latrine and therefore installed outside the house. However, due to the water seal that effectively prevents odours and flies from coming back up the pipe, pour flush pans can also be installed inside the house. This can on one-hand side help in reducing construction costs (shared walls and roof) and increase user’s comfort (no need to leave the house for visiting the toilet).

Because there are no mechanical parts, pour flush toilets are quite robust and rarely require repair. Despite the fact that it is a water-based toilet, it should be cleaned regularly to maintain hygiene and prevent the buildup of stains. To reduce water requirements for flushing and to prevent clogging, it is recommended that dry cleansing materials and products used for menstrual hygiene be collected separately and not flushed down the toilet.

(Adapted from: WATERAID 2008)

The urine diversion pour-flush pan, also known as wet ecosan pan, is essentially a modification of the conventional pour-flush squatting pan, but separates urine and faeces. This type of pan is especially useful in areas where plenty of water is easily available and handling of faeces is socially undesirable.

Both the pans have two holes - one for faeces and one for urine. The area between the holes is sloped towards the faeces hole as the water is collected together with the faeces. See also urine diversion components.