WATER SERVICE LINES
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Water service lines connect buried water mains to buildings to supply potable water, and sometimes to supply fire protection systems. There is usually a segment of the water line under the street, the property of the water utility, and a segment on the building property, belonging to the building owner. Water service lines may also be used to supply reclaimed water to applications such as irrigation.
Water service lines are plastic piping materials in nominal tubing sizes 1/2 In. to 3 In., depending on the size of the building and the estimated water demands. While some jurisdictions still use soft copper for these applications, polymer (plastic) piping materials provide the best combinations of safety, durability, ease of installation, longevity, and value.
Several types of tubing represented by PPI's Building & Construction Division (BCD) are used to distribute water to buildings and entire communities through municipal water service lines. These include crosslinked polyethylene (PEX) water tubing and specific types of polyethylene of raised temperature (PE-RT) water tubing. In addition, HDPE tubing from PPI's Municipal & Industrial Division (MID) is widely used for this application.
PEX tubing for municipal water service is typically required to meet the requirements of AWWA C904-2016 Crosslinked Polyethylene (PEX) Pressure Tubing, ½ In. (13 mm) Through 3 In. (76 mm), for Water Service. AWWA C904-16 requires PEX tubing to have a material designation code of 1306 or higher. PEX tubing meeting the requirements of ASTM F876 and/or CSA B137.5 may also be approved for this application.
PE-RT tubing for municipal water service is typically required to meet the requirements of AWWA C901-17 Polyethylene (PE) Pressure Pipe and Tubing, ¾ In. (19 mm) Through 3 In. (76 mm), for Water Service. AWWA C901-17 requires PE-RT tubing to have a material designation code of PE4710. PE-RT tubing meeting the requirements of ASTM F2769 and/or CSA B137.18 may also be approved for this application.
Since PEX and PE-RT tubing are both copper tube size (CTS) products, they utilize standard compression joint valves and fittings (when used with approved inserts), so they are easy and convenient to install. This includes brass valves and fittings made to AWWA C800 requirements, as well as polymer valves and fittings, when approved. Just as with HDPE pipes, inserts have negligible effect on pressure loss.
In addition, several types of metal and polymer fittings which are designed specifically for PEX and/or PE-RT tubing may be approved for water service applications. This includes fittings produced to nationally accredited standards such as ASTM F1807, F1960, F2080, and F2159.
As stated in AWWA C904, "Each such fitting should be qualified before use by investigation and by tests when necessary to determine that the fitting is suitable and safe for the intended servic." This includes specific approvals from fitting manufacturers for buried water service line applications.
Unlike buried metal pipes, plastic water service lines will not corrode or suffer mineral build-up, nor will they contribute dissolved metals into drinking water. Plastic water service lines must be certified to NSF/ANSI Std. 61 for drinking water safety.
PEX and PE-RT tubing are flexible to ease installation and resistant to freeze-break damage, lessening the chance of splitting or cracking. They provide excellent resistance to disinfectants such as chlorine and chloramines, reducing risk of long-term degradation.
Finally, PEX or PE-RT water service pipes can save up to half the cost of copper and have no scrap value, practically eliminating the chance of theft, a significant savings for budget-constrained waterworks professionals.
Advantages of PEX and PE-RT tubing materials for this application include:
- Durability and toughness to survive jobsite installations
- Flexibility to speed installation, including re-piping
- Resistance to corrosion, tuberculation, deposits
- Long coil lengths reduces fittings and scrap
- High chlorine and chloramine resistance
- No scrap value, avoiding jobsite theft
- Several fitting and joining options
- Lightweight, easy to transport
- Many sustainability benefits
Presentation - PEX Pipes for Service Line Applications
Design Guide - Residential PEX Water Supply Plumbing Systems
AWWA C904 - Crosslinked Polyethylene (PEX) Pressure Tubing, ½ In. (13 mm) Through 3 In. (76 mm), for Water Service
AWWA C901 - Polyethylene (PE) Pressure Pipe and Tubing, ¾ In. (19 mm) Through 3 In. (76 mm), for Water Service