First Flush
Diverter
Gutter
Inlet Filter
Cistern
Access
Gutter
Pump House
Cistern
Cistern Care and Clean Water
Essential Information for Your Health
Clean your roof, gutters,
diverters, screens, and  lters
Inspect your whole system
Treat your cistern water prior to use
Repair as soon as possible
after each inspection
Remove debris every 7 days
or when visible 
(note: diverters and flow
restrictors minimize debris and
sediment)
Deep clean and disinfect
cistern periodically by
draining the cistern,
removing sediment build-up,
and scrubbing the inside
Weekly for debris and sediment build-up
Monthly for structure cracks, wear, and tear
on seals
Measure the cistern water volume to treat
accurately
People Consume and Come in Contact with Cistern Water in Many Ways 
If your cistern water is contaminated, many of your daily activities may potentially expose you to harmful
contaminants. Preventing contamination is essential to protecting your health. 
Maintain a supply of
unscented bleach, chlorine
test tablets, litmus paper,
and filters
Sample and test your water
quality
Adjust treatment methods as
necessary
Maintain an emergency
supply of clean water
Clean
Protect
 
Maintain
16
12
8
4
Unscented
Bleach
Clean, Protect, and Maintain Your Cistern to Help Ensure Safe Water
For additional information
and resources on how to
clean, test, protect, and
maintain your cistern
water, please visit: 
March 2025
For more information contact:
Virgin Islands Department of
Planning and Natural Resources
340-773-1082
There are many types of treatment:
chlorination, UV, 3 stage treatment
Manual chlorination with diluted bleach is a
simple and effective treatment against
bacteria and viruses
Proper dosing, monitoring, and testing are
critical to ensure the safety of your water