In a crisis, rainwater can become one of the survivor’s greatest allies. Especially, if you live in an area with as few as 30 inches (12 cm) of precipitation (rain, snow, sleet, or hail that falls to the ground) a year, you may be able to live entirely off water falling on the roof of your home. That is, you could collect enough water from precipitation to meet all of your needs for cooking, cleaning, bathing, flushing toilets, watering gardens, and supplying a few chickens and a goat or cow – if you use the water efficiently.
In drier climates, you may not be able to live off rainwater, but you could capture enough water to irrigate a vegetable garden and fruit trees and perhaps supply a few animals that provide the food you’ll need to survive in style. Rainwater catchment systems are about as simple as they come. All you’ll need is a roof, gutters and downspouts, several rain barrels or a large tank (cistern), and water filters and purifiers.
Here are a few tips to get you started, as if you have the above, you are well on your way.
1. Check with local authorities to be sure that rainwater catchment systems are legal in your state. Some western states like Colorado prohibit rainwater collection, although there are a few rebellious individuals who have installed them anyway, flying successfully under the radar. We would not and can’t recommend that strategy, for legal reasons, but doubt anyone’s going to care if they’re capturing rainwater to survive. Even in “normal” times, illegal rainwater catchment is not a high-priority crime.
2. Remember, you can collect rainwater off your home, but also off roofs of other buildings such as garages, carports, sheds, and chicken coops. Doing so will greatly increase your supply of water.
3. The cleaner the roof the better. Metal and tile roofs produce cleaner water than asphalt shingle roofs. The cleaner the water, the less filtering and purification you’ll need to render the water drinkable. Bear in mind, however, if you’re going to simply use rainwater to irrigate gardens, fruit trees, and berry patches or supply a few chickens and a cow or goat, the water won’t need to be as clean up front.
4. If your home is surrounded by deciduous trees (shedding its leaves annually), install leaf guards on your gutters. At the very least, install a leaf screen on your downspout. Leaves clog up gutters, but more important, decaying leaves in gutters produce organic compounds that contaminate water supplies. They probably won’t kill you, but they may turn the water brown.
5. Install a roof washer. This is a rather simple device that diverts a small amount of water initially flowing off a roof during a rainstorm away from your cistern or rain barrel. This, in turn, prevents dirt and bird droppings, if any, from contaminating your drinking water supply.
6. If you live in a warm climate, rain barrels and cisterns can be installed above ground. Be sure to install tanks with opaque walls (not clear or translucent). If possible, install them in shady locations to keep the water cooler and protect the tank from UV radiation. Tanks with transparent or translucent walls allow sunlight to penetrate. Sunlight, in turn, supports algae that will contaminate your water.
7. If you live in a colder climate and want to collect water from snow melting off your roof, be sure to bury your cistern below the frost line or place it indoors – for example, in a basement. Only bury water tanks rated for underground burial.
8. If you are planning on drinking water from your system, it’s a good idea to install a tank rated for potable water, although a high-quality filter that removes organic chemicals may be all you need. If you are going to be using the water for cleaning, watering plants, and supplying animals, a clean plastic tank will generally suffice.
9. If you purchase used tanks, be sure they have never been used to store toxic chemicals such as herbicides or insecticides or natural oils like Vitamin E. The latter are very difficult to clean initially.
10. Rainwater can be emptied directly into open barrels from gutters cut off just above the rain barrel or can be filled by rainwater diverters that are installed in gutters.
11. Be sure to place a fine-mesh screen over open rain barrels to keep mosquitoes and other critters out. They’ll lay eggs in stagnant water. Mosquitoes are also potential carriers of some microorganisms that result in fatal diseases such as malaria and dengue in tropical and semitropical climates. They’re also known to spread the West Nile virus in temperate climates. Lest we forget, they’re also a nuisance for those who like to sit outdoors at night. A screened top will also prevent birds and mice from gaining access and drowning, then rotting, in your water supply.
12. Place rain barrels on cement blocks and install a spigot so you can easily remove water from the tank with a garden hose or bucket.
13. Remember, two or more rain barrels can be daisy chained (plumbed) together to increase the amount of water you collect.
14. If you install an underground cistern or an above ground barrel or tank, be sure to equip it with an overflow – a safe outlet that will carry excess water away from the tank should it top off in a rainstorm. Be sure the drains at least six to ten feet away from your foundation.
15. If you draw water out of a cistern with an electric pump, be sure the inlet to the pump is six inches or so off the bottom of the tank so it won’t suck up any sediment.
16. Drain rain barrels and cisterns every year or two and clean them to remove sediment or organic residues that may have collected on the bottom of the tank or organic matter such as algae attached to the walls.
17. Purify water intended for human consumption – for example, water in which you cook food or water you drink. Because rainwater collected off most roofs tends to be pretty clear (free of sediment or suspended solids), you may not need to filter it or it’ll require very little filtering. Do purify all potable water to eliminate potential parasites and microbes.
18. After you have set up your rainwater catchment system, have the water tested for a wide range of contaminants, especially if you live in or near a polluted city.
19. Purchase filters and purifiers, then try them out.