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University of the Virgin Islands        Funded by an EPA
Cooperative Extension Service      Environmental 
692-4080 (St. Croix)
        Education Grant
693-1080 (St. Thomas - St. John)
   
          
          Printed on recycled paper
CISTERN HEALTH TIPS
Û Use non-toxic
 roof coatings
Ý Install     
gutter   
screens
Ø Clean
    cistern    
   regularly 
Þ Check for leaks
Ù Disinfect     
   every month
Ü Eliminate
stagnant
gutter pools
Ú  Keep roofs and    
    gutters clean
  CISTERN HEALTH TIPS
Ø Clean cistern regularly. Empty and clean your cistern every 3 to 5
years. Cleaning removes sludge deposits and reduces contaminants like
coliform bacteria from your drinking water.
Ù Disinfect every month. Treat
cistern water with 5 fluid ounces of
liquid chlorine bleach (with no added
fragrance or dyes) per 1000 gallons
of water monthly. To find out ihow
many gallons of water are in your
cistern, multiply the length by the
width by the depth of the water by
7.5. If there are lots of leaves and
other debris in your cistern, you
need 
to 
clean 
your 
cistern.
Otherwise, you need to install water
filters that remove trihalomethane, a chemical formed by the reaction of
chlorine with organic debris.
Ú Keep roofs and gutters clean. Regularly clean rooftops, gutters
and pipes leading to cistern to reduce bacterial contamination. Leaf litter
and other organic debris are the major source of bacteria in cistern
drinking water that may cause illness.
Û Use non-toxic roof coatings. Many roof coatings, paints and
collection materials contain toxic substances such as zinc, copper, lead, and
plastic that can contaminate your cistern water. The National Sanitation
Federation (NSF) authorizes the following products safe to use for roof
and gutters: Weather Barrier 2000 Rain Coat, Flex PW 9162 EIP, Topcoat
W.O.B. (*WOB = without biocides), Vullkem 450/451 PWC.
Ü Eliminate stagnant gutter pools. Standing water creates mosquito
breeding areas, birdbaths and stagnant water that can harm the quality of
water entering your cistern.
Ý Install gutter screens. Screen all cistern openings (including the
overflow pipe) to prevent animals, insects and debris from entering your
cistern. Frequently remove any debris that collects on top of screens.
Þ Check for leaks. Cracks or leaks in your cistern can allow entry of
pollutants from failing septic systems, leaking petroleum storage
containers or other outside sources. Tree roots invading the cistern
indicate cracks or leaks.