Inlet Filter
First Flush 
Diverter
Cistern
 Access
Cistern
Pump House
Gutter
Gutter
Cistern Care and Clean Water
Essential Information for Your Health
Repair as soon as possible 
after each inspection
 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
Inspect your whole system
 Weekly for debris and sediment build-up
 Monthly for structure cracks, wear, 
and tear on seals
 Measure the cistern water volume to 
treat accurately 
Treat your cistern water prior to use
 There are many types of treatment: 
chlorination, UV, 3 stage treatment
 Manual chlorination with diluted bleach 
is a simple and effetive treatment against 
bacteria and viruses 
 Proper dosing, monitoring, and testing are 
critical to ensure the safety of your water
Clean your roof, gutters, 
diverters, screens, and filters
 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
Protect
Maintain
16
12
8
4
Unscented 
Bleach
Clean, Protect, and Maintain Your Cistern to Help Ensure Safe Water
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. 
For more information contact:
Virgin Islands Department of
Planning and Natural Resources
340-773-1082
For additional information 
and resources on how to 
clean, test, protect, and 
maintain your cistern 
water, please visit: