The primary functions of the plumbing system within the house are as follows:

1. To bring an adequate and potable supply of hot and cold water to the users of the dwelling.
2. To drain all waste water and sewage discharged from these fixtures into the public sewer, or private disposal system.

It is, therefore, very important that the housing inspector familiarize himself fully with all elements of these systems so that he may recognize inadequacies of the structure's plumbing as well as other code violations.

 

Water Service: The piping of a house service line should be as short as possible. Elbows and bends should be kept to a minimum since these reduce the pressure and therefore the supply of water to fixtures in the house. The house service line should also be protected from freezing. The burying of the line under 4 feet of soil is a commonly accepted depth to prevent freezing. This depth varies, however, across the country from north to south. The local or state plumbing code should be consulted for the recommended depth in your area of the country.
 
The materials used for a house service may be copper, cast iron, steel or wrought iron. The connections used should be compatible with the type of pipe used.

• Corporation stop - The corporation stop is connected to the water main. This connection is usually made of brass and can be connected to the main by use of a special tool without shutting off the municipal supply. The valve incorporated in the corporation stop permits the pressure to be maintained in the main while the service to the building is completed.
•  Curb stop - The curb stop is a similar valve used to isolate the building from the main for repairs, nonpayment of water bills, or flooded basements. Since the corporation stop is usually under the street and would necessitate breaking the pavement to reach the valve, the curb stop is used as the isolation valve.
•  Curb stop box - The curb stop box is an access box to the curb stop for opening and closing the valve. A long-handled wrench is used to reach the valve. 
•  Meter stop -The meter stop is a valve placed on the street side of the water meter to isolate the meter for installation or maintenance. Many codes require a gate valve on the house side of the meter to shut off water for house plumbing repairs. The curb and meter stops are not to be used frequently and can be ruined in a short time if used very frequently. 
•  Water meter - The water meter is a device used to measure the amount of water used in the house. It is usually the property of the city and is a very delicate instrument that should not be abused. Since the electric system is usually grounded to the water line, a grounding loop-device should be installed around the meter. Many meters come with a yoke that maintains electrical continuity even though the meter is removed.

Hot and Cold Water Main Lines: The hot and cold water main lines are usually hung from the basement ceiling and are attached to the water meter and hot-water tank on one side and the fixture supply risers on the other. These pipes should be installed in a neat manner and should be supported by pipe hangers or straps of sufficient strength and number to prevent sagging. Hot and cold water lines should be approximately 6 inches apart unless the hot water line is insulated. This is to insure that the cold water line does not pick up heat from the hot water line. The supply mains should have a drain valve or stop and waste valve in order to remove water from the system for repairs. These valves should be on the low end of the line or on the end of each fixture riser.

The fixture risers start at the basement main and rise vertically to the fixtures on the upper floors. In a one-family dwelling, riser branches will usually proceed from the main riser to each fixture grouping. In any event the fixture risers should not depend on the branch risers for support but should be supported with a pipe bracket. Each fixture is then connected to the branch riser by a separate line. The last fixture on a line is usually connected directly to the branch riser.

Hot Water Heaters: Hot water heaters are usually powered by electricity, fuel oil, gas, or in rare cases, coal or wood. They consist of a space for heating the water and a storage tank for providing hot water over a limited period of time. All hot water heaters should be fitted with a temperature-pressure relief valve no matter what fuel is used. This valve will operate when either the temperature or the pressure becomes too high due to an interruption of the water supply or a faulty thermostat.

Pipe Sizes: The size of basement mains and risers depends on the number of fixtures supplied. However, a 3/4 inch pipe is usually the minimum size used. This allows for deposits on the pipe due to hardness in the water and will usually give satisfactory volume and pressure.

 

 

Sanitary Drainage System: The proper sizing of the sanitary drain or house drain depends on the number of fixtures it serves. The usual minimum size is 6 inches in dial diameter. The materials used are usually cast iron, vitrified clay, plastic, and in rare cases, lead. For proper flow in the drain the pipe should be sized so that it flows approximately one-half full. This ensures proper scouring action so that the solids contained in the waste will not be deposited in the pipe.

• Sizing of house drain - The Uniform Plumbing Code Committee has developed a method of sizing of house drains in terms of "fixture units." One ''fixture unit" equals approximately 71 D2 gallons of water per minute. This is the surge flow-rate of water discharged from a wash basin in 1 minute. All other fixtures have been related to this unit.

Sanitary Drain Sizes

• Grade of house drain - A house drain or building sewer should be sloped toward the sewer to ensure scouring of the drain. The usual pitch of a house or building sewer is 1 D4 inch fall in 1 foot of length.
• Fixture and branch drains - A branch drain is a waste pipe that collects the waste from two or more fixtures and conveys it to the building or house sewer. It is sized in the same way as the house sewer, taking into account that all water closets must have a minimum 3-inch diameter drain, and only two water closets may connect into one 3-inch drain.

All branch drains must join the house drain with a "Y" -type fitting. The same is true for fixture drains joining branch drains. The "Y" fitting is used to eliminate, as much as possible, the deposit of solids in or near the connection. A build-up of these solids will cause a blockage in the drain.

• Traps - A plumbing trap is a device used in a waste system to prevent the passage of sewer gas into the structure and yet not hinder the fixture's discharge to any great extent. All fixtures connected to a household plumbing system should have a trap installed in the line.

The effect of sewer gases on the human body are known; many are extremely harmful. Additionally, certain sewer gases are explosive. A trap will prevent these gases from passing into the structure. The depth of the seal in a trap is usually 2 inches. A deep seal trap has a 4-inch seal.