Pan

Pan

Slovak term: Slovenský termín

1. A pan is a plumbing fixture designed to collect human waste directly from the user and discharge it to the drainage system by flushing (WHO 2006).
2. Basin to receive excreta which is then flushed into an outlet pipe by water poured in or by water delivered around the rim of the pan from a cistern (WHO 1992).

Explanation

The problems of flies, mosquitos and odor in simple pit latrines may be overcome simply and cheaply by the installation of a pan with a water seal in the defecating hole. The pan is cleared by pouring (or, better, adding) a few litres of water into the pan after defecation. The amount of water used varies between one and four litres depending mainly on the pan and trap geometry. Pans requiring a small amount of water for flushing have the added advantage of reducing the risk of groundwater pollution. The flushing water does not have to be clean. Laundry, bathing or any other similar water may be used to conserve clean water (WHO 1992).

Like ‘dry’ latrines, pour-flush toilets can be built with one or two pits for excreta disposal. They have a special pan, which is cast into the cover slab and is preferably equipped with a water seal for odour and fly control. Pour-flush latrines require between two and three litres of water per flush and are not suitable for areas with cold climates, impermeable soils or high water tables where the groundwater is a source of drinking water. They are also inappropriate where the use of solid objects for anal cleansing is the custom, as these may cause siphon blockage (WHO 1992). A pan can be found in many forms but requires a measured volume of flushing water to discharge the waste material into the drain and then transport that material through the sewer system for off site treatment. It can protect the building from sewer gases by a water trap seal, or a mechanical trap or vertical drop into water as found in an Aqua privy. Types of pans are:

• Squat pan or squatting pan, sometimes called an eastern pan.
• Pedestal pan, sometimes called a sitting water closet.
• Sitting wall hung pan.
• Pour flush latrine connected directly over a single leach pit.( a pour flush latrine requires a manual bucket flush)
• Aqua privy is also a wet system and consists of a vertical drop into a water tight tank, which stores and contains liquid effluent. (The water seal is created by the vertical drop pipe discharging below the fluid level of the tank.) (World Plumbing Council Working Group).

Example

A pan is a water flushing device found in most developed communities where water supply is available. It requires large volumes of water to operate. It can use a dual flush or single flush or a pour flush for its water volume. The minimum usable flush volume for successful discharge drain line is a 4.5/3 litre flush, which produces a trailing waste of 2.5 litres of flush volume (World Plumbing Council Working Group 2008).

References

• WHO (1992) A Guide to the Development of On-Site Sanitation
• WHO (2006) Health Aspects of Plumbing

Links

• WHO — The Health and Environment Lexicon