Piping should be supported to ensure alignment and to prevent sagging. Piping in the ground should be laid on a proper bed. Piping above ground should be supported with hooks, straps, bands, brackets and/or hangers suitable for the size of the piping, of adequate strength and quality, and located at intervals so as to prevent sagging, damage and vibration. Other piping should not support piping. Piping should not put strain upon connected equipment or appliances.

A common vent is one vent that serves more than one fixture, functioning as an individual vent for each fixture. Wet venting is venting single or double bathroom groups or combinations thereof, where one vent pipe may serve all the fixtures connected to the wet vent. Waste-stack venting is venting individual fixtures through a drainage stack, and the over-sized stack functions as the vent. Circuit venting is venting up to eight fixtures with a single vent pipe. A combination drain-and-vent system is restricted to floor drains, sinks and lavatories, and relies on the over-sized drain pipe. Island-fixture venting has a vent installed below the flood-level rim of the fixture before rising to connect to another vent.

Where the drainage system cannot drain by gravity to the sewer, an automatic pump or ejector can be used to discharge the soil and waste. The cover for the pump should be tightly sealed (gas-tight). Sumps, other than pneumatic ejectors, should be vented with a minimum 1-1/4-inch diameter vent pipe. Pumps use mechanical methods to discharge, and pneumatic ejectors use air pressure. Grinder pumps and ejectors pulverize solids to a near-liquid state and pump the slurry to the drainage system.

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Hot water is defined as water of a temperature of 110° F (43° C) or hotter. Tempered water ranges from 85° F to 110° F (29° C to 43° C), and the device supplying the tempered water must limit the temperature to 110° F (43° C).

Ball valves are less restrictive to flow than other valves. The handle clearly indicates whether the valve is open or closed. Ball valves do not control water flow.

Water Pressure Defects

In order to get the most meaningful results in relation to inspecting the water pressure, it is good practice to inspect the plumbing fixtures at the highest point in the house. And then move downwards to the lowest level of the building while running water at each fixture for a minute or two. Do not let water run at any fixture without close observation. Do not let water run unattended at any fixture.

The minimum static pressure at the dwelling entrance for either public or private water service (as determined by the local water authority) should be 40 psi (276 kPa). The maximum static pressure should be 80 psi (552 kPa). When the pressure from the public water main or private well exceeds 80 psi, a pressure-reducing valve or regulator should be installed at the point where the water service pipe enters the dwelling. The pressure regulator should be installed immediately downstream of the main shut-off valve. To allow a continuous flow of water to the dwelling, the water pressure-reducing valve is designed to remain in an open position if the component fails.

An air gap in a drainage system is the unobstructed vertical distance of free space between the outlet of the waste pipe and the flood-level rim of the receptacle into which the waste pipe is discharging. As an example in a commercial restaurant, the air gap would be between the drainpipe of a salad bar and the floor sink or tub drain.

There are deep wells (more than 25 feet deep) and shallow wells (25 feet or less). A typical well pump can pull up about 25 feet of water. If the well is deeper than 25 feet, the pump will have to be installed at the bottom of the well to push the water up. Pumps are better at pushing than pulling.