Alliance for Water Efficiency Forum
General Discussion Forum
A/C Condensation Water Quality
The safety of collecting the AC condensate into the rainwater cistern is directly related to the intended uses of the cistern water. AC condensate should never be considered potable. The condensate is collected on surfaces that often contain lead solder, zinc, and other heavy metals. The condensate will absob heavy metals as it collects on the AC surfaces. Condensate water is essentially distilled (pure) water when it condenses on the surfaces of the AC equipment; and as such it extremely absorbant of everything it comes in contact with. (Pure water is considered the universal solvent) Even if the water is sanitized, the metal contaminants remain in the water.
There are many appropriate uses for rainwater that are not appropriate for AC condensation water. For example: if you are only using the cistern for subsurface irrigation, the condensate should not be a problem. If you divert the condensate to the cistern, be sure to clearly label the condensate lines and the cistern as containing the AC condensate so, now and in the future, everyone knows that the cistern contains more than just rainwater.
Using the AC condensate is a great way to be garner water effeiciency, and a practice we encourage with the appropriate safety provisions. Depending on the facility and application, you should consider keeping the relatively cleaner rainwater separate from the AC condensate water.