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.

In the connection of a water distribution system to water-heating appliances, there is the potential for the migration of heated water into the water distribution piping. In a typical water distribution system, the water will expand into the public water service. If the expansion of water is not accommodated in the system, dangerously high pressures can develop that can cause damage to piping, components and the water heater.

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.

Inspection of private water sources, such as a well, is beyond the scope of a home inspection.

Check for physical damage to the tank, particularly rust and corrosion on the bottom of the tank. Check for water marks on the floor of the tank. Check for a leaking TPR valve and discharge pipe is installed. The covers at the electric heating elements should not be disturbed. Corrosion can be found where the water pipes are connected to the top of the tank. The electricity or the fuel may be shut off. There could be scorching at the burner cover area. The heat rollout shield should be in place. The draft hood and vent connector are often loosely attached. All tanks should be accessible with at least 24 inches of working space around them.