Plumbing Fixtures

Types of Interior Design Plumbing Fixtures and Fittings

What is a Plumbing Fixture?

A plumbing fixture generally refers to a receptacle with the necessary appearance designed for a specific purpose, the use of which results in the discharge of the waste contained in the fitting into a sanitary plumbing or sanitary drainage system. There are many plumbing  fixtures and fittings, from the pipes which carry the water to and from our fittings, to the taps and waste outlets that deliver it and remove it. A soil fixture may be a waste pan, urinal, slop hopper, autopsy table, bedpan or sanitary napkin disposal unit hence soil pipe. A waste fixture is any other fixture than a soil fixture hence waste pipe.

Plumbing Terms and Plumbing Fixture Definitions


Fall is the difference in level between two points.

Self-Cleansing Velocity

Self-cleansing velocity refers to the speed at which the contents within the pipeline should be flowing along a horizontal pipeline to prevent the collection of solids out of the fluid to the pipe surface.

Gully Trap

The point where the internal sanitary plumbing connects to the drainage system.


This is usually any vertical pipe including offsets through one or more floor levels. A soil stack is a stack, which carries the discharges from one or more soil fixtures and may also carry waste discharges. A waste stack carries only discharges from waste fixtures.


This is the fitting, usually in the form of a bent pipe that retains an amount of the wastewater as a seal. This allows the flow of the waste through the fitting while preventing gases in the soil or waste system from flowing back through the fitting into the living space.

Water Seal

This is the part of the trap that holds the content of water to prevent the gases flowing back into the room. There are a number of water seals, the most common being the P and S.

Air Pressure

All drainage and plumbing systems are designed to have a flow of air in them to help with preventing and inducing siphonage.

Induced Siphonage

Induced Siphonage is the loss of water from a trap caused by a reduction in pressure at the outlet of the trap. This condition is normally caused by flow from fixtures connected to the same pipe but at a higher level. Negative pressure is created in the pipe from the excessive flow from a higher fixture. Think of siphonage, as a form of suction or a common example is the pressure used to siphon fuel from the petrol tank of a car.


Self siphonage is similar but caused by the long leg of the pipe being long enough to create a suction or siphon. The actual air pressure being greater than the pressure in the pipe essentially causes the siphon effect. When the pipe is full of fluid and moving, there is no compensating air, then the water seal will get sucked, pushed or siphoned into the waste pipe. There are now self-venting traps that allow air into the system to stop the siphoning effects.


These are the items that allow air into the system to balance and stop the water seals from siphoning themselves out and allowing noxious gas into the living areas. They eliminate the positive and negative pressures exerted by fluid flowing in the pipes. Other benefits that vents provide are reducing the corrosive gases on metal piping and letting foul gases out of the system.

Wash Down Pan

This is the most common of toilet pans. It has a wash down pattern and eliminates all waste or cleans all waste from the pan by using free falling water to run around the rim and clean the pan. The weight or force of the water also forces all the waste through the water seal and into the soil pipe while the last of the water from the flush reseals the water seal. The full flush was once 11 litres but has now been reduced to between 6 and 3 litres, which is a consideration when specifying pans as an interior designer.

Pan Connector

This is the pipe connection between the soil pipe and the pan. This is normally by means of a large rubber ring connecting the pipe to the pan and the other end is connected to the soil pipe.


This is the tank above the pan that holds the water to flush the pan. It is controlled by a button or lever to allow the flow of the water which enables flushing. It is refilled by a water feed pipe that’s inlet valve is opened when the water is emptied from the cistern. A lever supported by a floating ball (called a ball cock) opens and closes the valve according to the cistern being empty or full.

Air Gap

This is a gap at the top of the cistern to prevent any water from the cistern (which is part of the soil fixture and therefore subject to contamination from bacteria) reentering the water supply by siphoning.

Isolating Valve

As the name implies this is a valve to isolate one part of the water system from the rest of the reticulation. This allows the system to be worked on without water pouring out of that part of the system. It is similar to a stop valve.


This is a joint that can be undone. They are usually beside or adjacent to a fixture to make removal easy if necessary.

More plumbing and drainage information

Plumbing and drainage
Plumbing systems
Drainage systems
Water pressure
Types of pipes for plumbing

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