April 23, 2009

Avoiding Paint-Related Taste & Odor Problems

by Tony Ippoliti

The American Water Works Association (AWWA) D102 Standard – Coating Steel Water Storage Tanks – requires that all “… coatings used on wet interior surfaces of the tank, shall have been tested and certified for potable water contact in accordance with NSF/ANSI¬†61. They shall have been evaluated for long-term fresh water resistance and the system shall have demonstrated satisfactory service in fresh water for at least eighteen months.

There are at least two benefits of this evaluation: that no contamination of the drinking water occurs and that no blistering of the coating occurs.

In addition, “taste & odor” problems, caused by inadequate ventilation, may be experienced in the community served by a newly painted tank. A paint-related taste & odor problem is generally defined as a solvent-like smell or taste in the water tank or at the homeowner’s tap. This results from hydrocarbon solvents being introduced into the water because ventilation to release these solvents was insufficient during the drying and curing of the coating.

The following statement is edited from the revised AWWA D102 Standard entitled Coating Steel Water-Storage Tanks:

A combination of forced and natural ventilation should be continued after coating application is completed to ensure complete curing and solvent removal. Coating life may be shortened if there is inadequate ventilation during the curing period and residual coatings solvent may contribute to taste and odor problems in stored water. Lower temperature or higher humidity may extend the time that ventilation is necessary. Heating can be used to shorten the forced ventilation period.”

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