- Loosely woven hemp rope that has been treated with oil or other waterproofing agent; it is used to caulk joints in a bell and spigot pipe and fittings.
- Obscure Glass:
- A glass that lets light through but is not totally transparent.
- Outside Diamter - The diameter of a pipe measured from the outside edge.
- Abbreviation for Original Equipment Manufacturer.
- A tubular component which permits the offsetting of a drainage run in the same basic direction.
- A unit of electrical resistance.
- Oil Powered:
- A water heater that uses oil as its fuel source.
- One-Handle Faucet:
- Provides on/off activation and temperature setting with a single operation.
- One Piece Toilet:
- A toilet in which the tank and bowl are manufactured as single vitreous china fixture. Typically, one-piece toilets have a lower profile than two-piece toilets.
- Open Front:
- A style of toilet seat rim where there is an open space about three inches wide at the front. Considered more sanitary in commercial applications where constant
usage exceeds janitorial sanitation.
- Operating Cost:
- The cost of running a water heater for a given time period.
- Orbital Weld:
- A circumferential, full fusion weld used to join together two lengths of tubing. It is a GTAW welding process. Usually to join coiled lengths.
- Organic Matter:
- Plant and animal residues, or substances made by living organisms.
- An opening through which gas is discharged and whereby the flow of gas is limited and/or controlled.
- The movement of water molecules through a thin membrane.
- Round rubber washer used to create a watertight seal.
- The opening through which the water exits the pump.
- Outlet Sewer:
- Pipe section in a septic system which runs between the septic tank and the drainage field.
- Overflow Hood:
- On a bath drain, the decorative hood concealing the overflow.
- Overflow Tube:
- The vertical tube inside a toilet tank that directs water into the bowl in case the ballcock malfunctions. It is usually part of the flush valve. It prevents
potential water damage caused by a tank overflow. A constant running condition alerts the user to a problem. On most toilets, the overflow tube also has a refill tube flowing
into it, which directs water from the ballcock through the overflow tube to the bowl, after a siphon break.
- An unstable form of oxygen (O3), which can be generated by an electrical discharge through air or regular oxygen. It is a strong oxidizing agent
and has been used in water conditioning as a disinfectant.