"Understanding Your Home" by Building Inspector Mark Visser
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Active plumbing leaks
Drains for bathtubs, toilets, vanity, showers and dishwashers are usually located within the floor or wall construction. Water damage resulting from major leaks are usually easy to find but small leaks can go unnoticed for a long time. So, by the time you spot water stains on the ceiling a lot of damage may have occurred already and immediate action is required.
Non-functional drains
Drains are considered non-functional if the water flow from the fixture is faster than the drainage. Drains should be kept functional at all times. Slow or clogged drains can lead to fixture overflow and extensive water damage.
Pipe material
Pipe material for vent and waste lines could be ABS, cast iron, galvanized steel or copper.



Clean-out in basement
Vent and Waste Systems
Plumbing - How it Works
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Plumbing vent and waste systems. Floor drains. Plumbing leaks. Sump pumps.

The vent, drain and waste system in homes is extensive and more complicated than the water supply system. Most of the system is inside finished walls and ceilings, while the sewer lines are buried underneath the basement floor.
The waste line is the outflow, or drainage, of the plumbing system. Unlike the supply lines, the waste lines are not pressurized and rely on gravity for drainage.
Fixtures are hooked up to the drains with a trap that contains water.
Water in the trap prevents sewer gases from escaping into the house. In order that the traps are not emptied by the suction of the draining water, all drains are connected to a .....
vent pipe which allows air to enter the system and the waste to drain freely. The vent pipe is connected to the .....
soil stack which passes through the roof. The warm moist air rising up the stack tends to condense on the inside of the stack section above the roof line. If the stack is more than 12" (300 mm) above the roof, there is the potential for complete frost closure. Frost closure can be prevented by insulating the vent pipes in the attic.

Vent and waste system
Clean-outs. The waste system should have clean-outs for removal of sediments and obstructions. Clean-outs are watertight fittings with a removable plug and are usually located below fixtures and at junctions in the waste line.
Storm water drainage systems are used to remove rainwater and groundwater. Downspouts from roofs and weeping tiles may each be separately connected to storm sewers or in newer constructions where the downspouts are surface drained. The indoor plumbing for rural homes will be the same as homes in the city, except that the water lines are pressurized by a water pump.
Basement floor drains. To prevent sewer gases from escaping the drains, water is added to keep the drains filled. In newer homes this is done by a direct hook-up to a faucet. Water is supplied to the drain every time the faucet is used.
Floor drains in older homes do not have a trap seal primer or 'wet trap' and will dry out if not used regularly. Water should be poured down the drain occasionally. As an alternative, mineral or baby oil can be used which will not evaporate as readily as water.
Sump pumps. If the underground storm drainage lines in a house are lower than the public storm sewer or ditches, they can be connected to a sump (a receiving tank in the floor). A pump in the tank lifts the water to a higher level for discharge.
There are two types of sump pumps, as illustrated in the section about sump pumps. The pedestal-type is the most common one. Pumps are relatively inexpensive and it is a good practice to keep a spare handy or to install a back-up system. Sumps should have a notched cover for safety reasons and to keep out debris which may clog the pump.
See also private disposal systems; Septic tank and septic bed.
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