Planning for disruption to your potable water supply is a primary goal, especially on the west coast where we are in a High Seismic Zone.
Looking back on Christchurch after their earthquake it is no longer good enough to have 72 hrs worth of supplies, and a month to three months may be required if municipal services are severed. Planning where to access water and how to treat it should be critical to every home, every community centre, every emergency response unit (Fire, Police, Ambulance, Hospital). Conventional water sources are not always reliable – take a local municipality who’s emergency water source is a local lake; this lake had a Blue Green Algae bloom, an algae that produces toxins not removed by the emergency filtration system, thus rendering their sole emergency source as non-useable. The solution… small distributed water systems.
Storage Systems are not guaranteed potable:
Though rain is fairly clean, once it comes into contact with collection susrfaces and conveyance systems, a host of contaminants can be picked up and deposited in a storage cistern. This does not make it off-limits in cases of emergency, it does mean that one requires methods to turn it into a potable source.
Emergency Water Treatments:
If you treat water stored in a cistern it is wise to divert new water so as not to introduce new contaminants.
1 minute and then allow to naturally cool
Chlorine Bleach – 5% or 6% unscented
Disinfect water using household bleach if you can’t boil water. Do not use scented, color safe, or bleaches with added cleaners.
Large quantities2.5 ounces (5 tablespoons) per 1000 gallons.
- Small quantities (from US EPA)
Locate a clean dropper from your medicine cabinet or emergency supply kit.
- Locate a fresh liquid chlorine bleach or liquid chlorine bleach that is stored at room temperatures for less than one year.
- Use the table below as a guide to decide how muchwater containers with medicine dropper bleach you should add to the water, for example, add 6 drops of bleach to each gallon of water.
- Double the amount of bleach if the water is cloudy, colored, or very cold.
- Stir and let stand for 30 minutes. The water should have a slight chlorine odor. If it doesn’t, repeat the dosage and let stand for another 15 minutes before use.If the chlorine taste is too strong, pour the water from one clean container to another and let it stand for a few hours before use.
- Volume of Water and Amount of Bleach to Add
1 quart/liter — 2 drops
1 gallon — 6 drops
2 gallons — 12 drops (1/8 teaspoon)
4 gallons — 1/4 teaspoon
8 gallons — 1/2 teaspoon
Ceramic Doulton Sterasyl filter (0.5 micron) (NSF 61 certification)
These filters have silver impregnated into the ceramic so as the ceramic mechanically filters items like cryptosporidium and and giardia, the silver sterilizes and thus there is no need for boiling. There are many different systems that accept these filters, some sit on the counter and allow water to gravity feed through the filter. The internet has many sites that sell these. Link
Iodine Lugol’s Solution (5%)
Can treat small quantities of water at a rate of 2 drops of Lugol’s Solution per 1 litre and sit 24 hrs, or 4 drops and sit 30 minutes.
Common household iodine (2%) (or “tincture of iodine”) (US EPA)
Add five drops of 2% tincture of iodine to each quart or liter of water that you are disinfecting. If the water is cloudy or colored, add 10 drops of iodine. Stir and let the water stand for at least 30 minutes before use.
Solar Disinfection (WHO)
Solar disinfection – Ultra-violent rays from the sun are used to inactivate and destroy pathogens present in water. Fill transparent plastic containers with water and expose them to full sunlight for about five hours (or two consecutive days under 100% cloudy sky). Disinfection occurs by a combination of radiation and thermal treatment. If a water temperature of least 50oC is achieved, an exposure period of one hour is sufficient. Solar disinfection requires clear water to be effective.
An enhanced example is the SODIS system, whereby half-blackened bottles are used to increase the heat gain, with the clear side of the bottle facing the sun, as shown above.
Water disinfection tablets.
You can disinfect water with tablets that contain chlorine, iodine, chlorine dioxide, or other disinfecting agents. These tablets are available online or at pharmacies and sporting goods stores. Follow the instructions on the product label as each product may have a different strength.