Recommended materials for storage tanks in lab ultrapure water systems

In daily laboratory operations, pure water is indispensable—whether for cleaning laboratory vessels or preparing reagents used in experiments. In most cases, the pure water produced by a laboratory water purification system is used directly. This approach not only offers convenience but also minimizes the risk of external contamination. While storing ultrapure water is generally not advisable, it may be necessary when the demand is relatively large or before further filtering the water. Currently, most laboratory ultrapure water systems utilize storage tanks to store the produced ultrapure water. As ultrapure water is an excellent solvent, most storage tanks are constructed from inert materials.

When purchasing a laboratory water purification system, the tank material is often overlooked. While all purified water tanks are made of inert materials, which one is better? The main materials for purified water storage tanks on the market are polyethylene (PE) and polypropylene (PP). We recommend selecting tanks made of PE. Why is PP not recommended for storage tanks? There are two primary reasons:

We always emphasize that after water purification, external influences on the purified water should be minimized. PE exhibits greater stability than PP, so its leaching effect on pure water is smaller compared to PP. The methyl groups in polypropylene are relatively prone to detachment. Although the probability is low, such occurrences should be minimized in rigorous experiments.

In routine use of laboratory water purification systems, PP storage tanks are observed to be less durable than those made of PE. PP is more susceptible to oxidative degradation under ultraviolet light and thermal exposure. Moreover, to enhance its impact resistance, impact modifiers must be added during the molding of PP components. This addition introduces an additional risk of external substances affecting water purity.

We hope this information assists you in selecting a storage tank for your laboratory water purification system.