Is HDPE Pipe Safe For Drinking Water?
Quick response to problems: Metal pipes and pipe materials have always had problems with corrosion, deposition, pressure resistance, thermal conductivity, and chemical resistance. Cross-linked polyethylene (PEX) pipe is an alternative, but the available sizes are too small for major commercial installations.
Plastic pipes and tubes are widely used to transport various types of gases and liquids. Due to inherent advantages, plastic may be more popular than metal. They are lighter in weight, do not require an open flame connection, and are flexible, which simplifies installation and reduces breakage caused by freezing.
Plastics are generally lower in cost and can resist the corrosion and scaling that plague metals in certain applications.
Due to concerns about the migration of chemical contaminants, plastics used to hold food and water are undergoing stricter scrutiny. Many recent studies and media have focused on endocrine-disrupting chemicals, such as bisphenol a found in polycarbonate baby bottles, and phthalates in vinyl toys and other products.
High-density polyethylene (HDPE) pipes have been used in non-potable water applications for decades. In particular, HDPE pipe is usually the first choice for welding joints. Although special equipment is required to form the weld seam, welding eliminates the need for separate parts, which is a common source of leakage and infiltration of contaminants. HDPE is very flexible and can tolerate more severe field processing than brittle polymers. The flexibility also allows for steering in the piping system without the need for additional joints.
For drinking water, HDPE was initially limited to cold water applications, because early formulations were not strong enough for high-temperature hot water systems. The supplier subsequently developed cross-linked polyethylene (PEX) with superior strength and high-temperature properties. EX is very common in radiant floor heating applications and is increasingly used in domestic hot/cold water systems. However, the available pipe size is too small for larger commercial installations. HDPE and PEX are both polyethylene (PE), but because of their different properties, care should be taken not to confuse these two very different materials.
HDPE can be used as an inner lining for hot water. In multi-layer pipes, the strength is provided by another layer of pipe, such as aluminum, but multi-layer pipes cannot provide all the performance advantages of plastics alone.
HDPE is a widely recognized standard organization and code agency for potable cold water applications.
Chemical contaminants in HDPE pipe materials will indeed migrate into the water, and certain plastic pipes will penetrate into the water when in contact with contaminated soil. However, these studies are still inconclusive as to the impact of these pollutants on human health.
Those who expect to use HDPE, especially in hot water applications, should require suppliers to provide data and certifications on chemical migration, taste and odor, and high-temperature performance.
Those who are most worried about chemical pollution may be more willing to give up the use of plastics altogether, but compared to copper, plastic pipes have important advantages in terms of installation, use, cost, and the environment.
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