Polyethylene (abbreviated PE) is the most common plastic. Many kinds of polyethylene are known, with most having the chemical formula (C2H4)n.

High-density polyethylene (HDPE) is the polyethylene most commonly used for water tank manufacturing. While there are different styles of PE tanks on the market, the traditional round tank with domed top is the best choice for rainwater collection.

HDPE is defined by a density of greater or equal to 0.941 g/cm3. HDPE has a low degree of branching. The mostly linear molecules pack together well, so intermolecular forces are stronger than in highly branched polymers. HDPE has high tensile strength.

Advantages:

  • Economical storage solution for water
  • Impact resistant, easily mold-able, and can have some UV sunlight degradation protection
  • Available in a wide variety of sizes, capacities, and colors
  • Provides strength and durability for years of reliable performance
  • Can be food grade, NSF approved for drinking water storage
  • PE tanks are easier to move and install by hand due to their strength and lightness
  • Lighter weight of PE tanks can mean lower shipping cost when compared to other tank materials
  • PE tanks won’t rust over time and have to be replaced
  • If a PE tank is accidentally punctured, it can easily be repaired, in most cases

 

Disadvantages:

  • Aesthetic appearance of PE tanks can be lacking
  • UV sunlight degradation of the plastic over the years even if a UV inhibitor is in the plastic
  • Even though PE tanks come in a variety of sizes, they are set sizes so there are “gaps” in their product sizing which could cause issues of not being able to install as large of tank you want because the right sized tank is a size that is in the gap of the PE tank selection.
  • If you desire a large rainwater storage volume, you would have to use multiple PE tanks which could end up wasting space. Think about a round peg going into a square or a rectangle.
  • PE tanks are susceptible to wild fires
  • The manufacturing process of plastic from oil is a heavy pollution generating industry
Group of poly tanks
Group of three 2500 gallon poly tanks

Did you know...

During an average year of rainfall, a typical 2,000 square foot house in Austin could collect almost 40,000 gallons of rainwater.

Don’t Waste This Opportunity

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