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Navigating Island Life: Cisterns and Water Filtration

Shower Head with Running Water, Blue background

Island life brings with it so many wonderful qualities, beautiful beaches to visit year-round, perfect weather and peaceful living. But island life also brings a few unique challenges to which statesiders are not accustom. One of those is household water collection and purification.

In the U.S. Virgin Islands and on most Caribbean islands, the average house collects rain water that falls on the roof in a cistern. This water is then pumped throughout the house, as opposed to the average stateside house that is connected to a city water source. Unlike a city water source that is filtered to meet quality standards, cistern water is completely unfiltered. So it is up to each house to install a filter, if desired, similar to a stateside well water set-up.

There are many ways to control the quality of the water that is collected by a cistern and pumped into a house:

The first area to focus on is the roof. Since the water that is collected in the cistern starts out as rain water, it is initially contaminate free at the time it falls on the roof. If the roof and gutter system are kept clean and free of any organic material (decaying leaves, other plant matter, etc.) then the water will still be clean by the time it gets into the cistern.

The second area is the cistern itself, which is the most likely place for water to pick-up contaminates. This is where the water collects and then sits stagnant as it waits to be pumped into the house piping. It is recommended to drain, clean and re-coat a cistern every few years, but even with that, it is likely that bacteria or other foreign matter will end up in the cistern water. Therefore, disinfection and filtration is necessary.

For disinfecting (removing potentially hazardous bacteria and viruses) there are a few different options. The most common is bleaching the cistern water. There are a lot of websites that discuss the amount of bleach to use based on the amount of water in the cistern, the Center for Disease Control (CDC) lists this information.

Once the cistern is disinfected you still need to filter the water to remove particulates. There are many, many options for filtering. You can install a reverse osmosis system under the kitchen sink specifically for drinking water, or you can install a whole house filter. A whole house filter usually involves a two or three stage filter set-up, with the first stage being a sediment filter and the next stage(s) being carbon block filters. There are also filters that use UV light.

No matter which method you use to treat your cistern water, get your water tested regularly to ensure it is safe for your family. If you aren’t sure of the quality of your water, consider buying bottled water from a trusted water purification company, which may be purchased and refilled at any grocery store.

Ready to live where you may never pay a water bill again?  When you’re ready to make America’s Paradise your home, contact Chris and Kerri Hanley to start your home search on St. Croix and St. Thomas.  As the top broker on-island year after year, Chris is the authority on Virgin Islands real estate.  Start by downloading their free St. Croix Event Guide to find the perfect time for an extended stay on-island:

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