Water Purification 101
If your water comes from a private source, such as a ground well or flowing spring, there are some important facts you should know.
- v People drawing water from private wells are responsible for assuring that the water is safe for consumption.
- v The U.S. Environmental Protection Agency only requires that municipal water sources be tested for about 80 of the 75,000 known contaminants.
- v The standards for safe drinking water are established for a 175-pound healthy adult and may not be satisfactory for children, women who are pregnant or nursing, or adults with compromised immune systems.
There are many methods that can be used to purify water and each one is best for removing a certain type of impurity or contaminant but may not be effective at all for others. Some of the more common water purification technologies are:
- v Distilliation - Water is heated to boiling and then cooled to condense the water vapor. Impurities are filtered out by the evaporation
- o Effective for: bacteria, lead, nitrate, sodium chloride, organic chemicals and pesticides
- o Pros: removes a wide range of contaminants, reusable
- o Cons: slow, requires a large amount of water and energy
- v Carbon Filtration - Water is passed through an activated carbon filter that absorbs odors, flavors, organic compounds and many hazardous chemicals
- o Effective for: hydrogen sulfide, radon, chlorine, volatile organic compounds, pesticides, benzene, colors and orders
- o Pros: removes objectionable odors and flavors
- o Cons: won’t remove heavy metals and the filter must be replaced periodically
- v Ion Exchange - water is percolated through a layer of resin beads that have a sodium exchange coating to “soften” water before using other treatment methods
- o Effective for: nitrates, sulfates, fluorides, iron, magnesium, calcium and manganese
- o Pros: removes dissolved minerals and metals effectively at a relatively low initial cost
- o Cons: doesn’t remove bacteria - in fact, beads can become breading ground for bacteria
- v Micro Filtration - water is passed through a porous filter to remove sediments and suspended materials
- o Effective for: sediments
- o Pros: removes all suspended impurities larger than filter pore size
- o Cons: doesn’t removed dissolved contaminants
- v Ultraviolet Radiation - low level ultraviolet light kills bacterial and viral pathogens but leaves no radioactive trace
- o Effective for: bacteria, viruses
- o Pros: sanitizes water
- o Cons: doesn’t remove suspended particles or ions
As you can see, no single purification method removes ALL the contaminants from water and you may have to employ several methods to make your water safe for drinking and cooking.
Like many types of low-lying waterfront property, islands may be prone to collecting pools of water that can not only disturb the island’s use, but pose a serious health hazard. Whether caused by storms, erosion or just naturally-occurring, these tepid pools can form a breeding ground for disease-carrying insects such as mosquitoes and flies. Swamp or marsh areas of the island may also be undesirable aesthetically, or interfere with intended construction. Getting rid of excess water is a simple project that requires some help from a durable water pump.
It’s not like the difficulties posed by city life vanished the minute you bought your island. Realistically, unless you’ve got it in mind to live off wild mollusks or tree bark, you’re going to accumulate a fair bit of waste. With all the options for creative living posed by your private little world, how about options for disposing recyclable waste in an equally creative manner?
Water harvesting is one of the oldest ‘crops’ in the world. As long ago as 2,000 years, human civilizations have relied on rain to settle, sustain, and sow land of all variety. Deserts in the Negev, nomads in Africa, and elaborate Roman villas in Italy have all been designed to exploit the common aspects of rain collecting. The efficacy of the practice is testified to by the fact that water harvesting is still around today. The world’s largest existing water tank was built around 600 B.C. and remains standing and in use in Turkey. Remote areas are still dependent on some amount of rainfall for a variety of purposes…any one of which is part of the mosaic of human survival. Rain water allows for supplementary crop maintenance, dilution, human consumption, and support for a variety of livestock.Islands are common locations for water harvesting, especially using rainwater. Islands that are relatively close to a mainland often have water piped or carried in. Despite any distinctions between island and mainland rainwater harvesting, there are three common engineering elements: collection, conveyance, and storage. How these three interrelated elements are applied to their environment, however, vary greatly between urban and island environments. 
From Canada, to Mexico to Dubai, for centuries humans have been building islands. The major limitation in the construction of islands is that they can only be built in shallow water due to the expense and resource intensiveness of construction. However, this is a limitation that may soon be history with the development of a new deep water platform.