Polyvinyl chloride (PVC) is the standard for residential supply and waste piping. PVC plastic piping has been shown to outgas diethyl phthalate, trimethylhexane, aliphatic hydrocarbons, and other harmful gases. It should not be used for water supply piping in a healthy home. Because of the pollution resulting from both the manufacture and the disposal of PVC piping, we recommend seeking alternatives for waste lines as well.
Although we can choose the type of supply pipe we want in a new home, we have no control over how water is delivered to our propertyline. Well water is often delivered through PVC piping. Municipal water supply can be piped through a variety of unsavory piping, including PVC and asbestos cement. We recommend whole house water purification at the point where water enters the house. In Division n we outlined several whole-house water purification strategies. From the point at which water is purified, it makes sense to distribute it in piping that will not have an adverse affect on water quality. Your specifications could include one of the following acceptable alternatives for supply piping:
• Type L or Type M copper: Solder shall be lead-free silver solder. The system shall be flushed prior to occupancy to eliminate any flux from the soldering operation.
• Wirsbo Aquapex: A crosslinked polyethylene that shall be installed by a certified installer.
Waste drain systems do not have the same water quality concerns as supply piping does and are almost always plastic because it is most economical. We prefer to specify ABS piping because of the problems associated with the production and burning of PVC piping. Pipe assembly glues are highly volatile and
toxic and their use onsite should be carefully managed to reduce pollution. You may wish to specify the following:
• Assemble pipes with the longest pieces possible to minimize the amount of glue or solder required.
• When possible, glue waste pipe assembly outside the building envelope.
• Wipe up excessive glues and protect all surfaces from glue drips and spills.
• Whenever glue is being used inside the structure, provide adequate ventilation until all odors are dissipated.
Appliances containing water, such as water heaters and washing machines, can malfunction and leak. You can avoid the subsequent water damage and mold if you plan for this possibility If floor drains or drain pans are strategically located, the water from accidental spills can be diverted to the sewer line or to the outdoors. Drains that lead to the sewer line should be installed with a trap to prevent unwanted sewer gases from entering the home. It is important that the traps be “primed,” or kept filled with water, which creates a physical barrier against the entry of sewer gases. Selfpriming drains can be installed so that the trap will remain filled with water without additional maintenance.
Where plumbing penetrates walls and ceilings, the air space created around the opening must be completely sealed to prevent unwanted air infiltration. Consider specifying the following:
Wherever plumbing penetrates the wall, aquarium-grade 100 percent silicone caulking shall be applied to create an airtight seal.
In some communities, sewage systems periodically back up and flow into homes, leading to devastating contamination. Backflow prevention devices installed on the home waste line will usually prevent this. The local planning department may be able to help you determine if backflow prevention devices are advisable. In many communities, claims for sewage damage will not be paid unless such devices were in place prior to the incident.