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Current IssueAugust 01, 2014
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Ask The Expert: Distilled water & plastic; storage tips for bottlers
07/01/2004 
 
Question:

Q I am mailing from the State of Johor in Malayisa. We are a distilled water bottler and are expanding our plant; thus, we need to buy new water storage tanks. Our previous tanks are polycarbonate tanks from America; however, there seems to be no such supplier in my country that manufactures such big storage tanks (1,000 gallons and above). And stainless steel is too expensive now. Therefore, we are looking for other alternatives. Someone has quoted me using a polyethelene tank instead. Please reply whether it is advisable to use polyethelene for storage of distilled water. Data specifications for polyethelene are attached herewith. Thank you.

Lynda Loh, Director
Pure Water (JB) SDN BHD
Bahru, Johor, Malaysia

 

Answer: 

A Storage tanks can be made from many different kinds of plastics. The type of plastic used will determine the method of tank fabrication and ultimately the price of the tank. Some plastics lend themselves to be molded into the final shape, while others need to be fabricated piece by piece. Molded tanks are generally less expensive and much more readily available.

A polycarbonate tank would need to be custom built. The only special property about polycarbonate is that it is extremely clear (like glass). Otherwise, polycarbonate has no special properties that make it a better choice for holding distilled water.

Polyethylene tanks are widely available in many shapes and sizes up to 10,000 gallons. There are different types of polyethylene, including medium density and high density. Both products are excellent for water up to 140°F. The medium density tanks are good for liquids with a specific gravity of less than 1.5 (water has a specific gravity of 1.0) and the high density tanks are good to a specific gravity of 1.8.

Polyethylene meets the U.S. Food and Drug Administration (FDA) standards for potable water. These tanks are easy to find in an any farm supply store. You can see a variety of tanks online at www.usplastic.com. Pricing on the medium density tanks are usually around US$0.50 per gallon; thus, a 1,000 gallon tank should cost around US$500. Good luck with your tank.

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