Water catchment systems

Water from catchment systems in vog prone areas can become acidic and leach harmful contaminants, such as lead, copper, and zinc, from roofing and plumbing materials, especially from older homes. Catchment water used for drinking or food preparation should be carefully monitored. Methods for adjusting water catchment pH include adding baking soda to the tank, or using an inline pH adjusting filter.

Volcanic ash can also get into the water, causing contamination, and interfere with common water treatment methods such as filtration and chlorination. For health and safety reasons, in general, the Hawaii Department of Health does not recommend using catchment water for drinking or preparing food. County water spigots can be used instead as a safer water supply.


1. How to make a home rainwater catchment system safe for domestic use

Hawaii State Department of Health
This HDOH page gives information on maintaining catchment systems in Hawaii and how to access subsidized water testing for lead and copper.




2. Guidelines on rainwater catchment systems for Hawai`i

University of Hawaii
Further advice on maintaining catchment systems is given in this CTAHR document which is also available for PDF download, or to order in hard copy.





3. Specific advice on precautionary measures for catchment users during ashfall

Hawaii State Department of Health
This HDOH document gives information on maintaining catchment systems in Hawaii during ashfall, as was experienced following the opening of Halemaʻumaʻu vent in 2008.



4. Impacts of vog on rainwater catchment systems

Thomas, D. and Macomber, T., University of Hawaii/CTAHR 

A Preliminary Survey of Rainfall Catchment Systems for Impacts Associated with Halema’uma’u Gas Discharge