WSG 170
                                                           Date Signed: October 23, 2003


SUBJECT:   Potable Water Heat Exchangers

FROM:      Cynthia C. Dougherty, Director
             Office of Ground Water and Drinking Water

TO:          Water Division Directors
       This letter is to update and confirm my October 1996 memo (attached) regarding the
Office of Ground Water and Drinking Water's (OGWDW) long-standing policy of discouraging
the use of potable water source heat pumps. Our numerous concerns, including the potential for
deterioration of water quality, as documented over the last decade or more continue to stand.

       Over the years, OGWDW and EPA's Office of Research and Development (ORD) have
cited a variety of concerns about the use of heat pumps that return water to the distribution
system, including: the potential for contamination of drinking water with metal byproducts
(copper and lead), oils and refrigerators; potential for increased bacterial growth this might
stimulate in the distribution system; and the potential for liability to the drinking water system
should health be impaired as a result of the heat pump interconnection. Other emerging issues
include potential risks to drinking water security that might arise with the establishment of cross
connections between heat exchangers and potable water mains.

       Although ORD has developed a test protocol, neither they nor we are aware of any new
research, test results or other data that address the issues associated with the use of this heat
pump technology. In the absence of satisfactory test results,  our position discouraging the use of
heat exchangers without significant additional study remains unchanged.  We therefore advise
you to maintain your vigilance as previously suggested with respect to any public health or water
quality problems that develop and to communicate with your states and provide support as the
need arises.

       If you have any questions about our policy on heat exchangers, please call  me or contact
Bill Diamond, Director, Drinking Water Protection Division, Office of Ground Water and
Drinking Water, at (202) 564-3751.

cc: James Taft, ASDWA