Groundwater
Wells
A well is simply a hole dug or drilled down to the level of the
groundwater. Locating an appropriate site for a well can be a challenge,
especially since hand-digging a well is very labour intensive, and
you don’t want to spend time and effort digging a dry well.
If there is a dry season where you are, try to dig the well at the
end of it. That is the time when the groundwater level is the lowest.
If you dig when the groundwater is high, it will move down in dryer
weather, leaving your well dry. Look for indicators of a good site,
such as healthy, green vegetation. Annual plants, such as ferns, are not good indicators, because they come and go with the
seasons. Look for year-round plants which grow where water is close
to the surface, like willow and cedar.
When siting a well, you want to try to find a place where the water
table is as close as possible to the surface, so that your well will
be easy to dig, but also where the water table is deep, so that seasonal
variations will not dry your well. Refer to the image below, and to
hydrological and topographical maps for your area.
You can also place a well near a river (but at least 15 m away) which
will be “recharged” be the river water. However, you should
never place a well where it may be flooded by surface water, which
could cause contamination.
Wells should never be dug near latrines, rubbish dumps or animal
pens. Try to leave a distance of at least 30 metres (100 feet) from
these possible sources of groundwater pollution. Wells should be at
least 100 metres (330 feet) from possible sources of industrial pollution.
There are several techniques for well digging and drilling that are
appropriate for an improvised situation. However, some methods require
installing a pipe and hand-pump to operate, which is beyond the scope
of this excerpt booklet. (For more information on simple drilling
techniques, see WELL Technical Brief #43: Simple Drilling Methods,
available online. You can also refer to D.V. Allen’s Low-Cost
Hand Drilling, Consallen Group Sales Ltd, 1993.)
The most appropriate method for an improvised situation is to simply dig
a hole in the ground. A diameter of at least 1.2 metres (4 feet) is
needed for two people digging together. UNEP suggests digging a well
with a height to width ratio of 2:1. The well can have a deeper ratio
if the soil around it is very cohesive, but if the soil is uncohesive
it may need reinforcement. Dug wells have definite depth limitations,
for safety and practical reasons, and so if your water table is very
deep, they may not be appropriate. However, the deeper a well is,
the better the quality.
Mark out a 1.2 metre (or larger) circle at the appropriate location,
and begin digging. After you’ve dug about one metre (3 feet),
place a tripod or anchored log over the well opening as you dig. This
can be used with a rope and bucket to remove soil from the bottom
of the well. Ideally, the well will be dug two metres (6.5 feet) below
the top of the water table. Stop digging when the well has reached
that depth, or when it’s not safe to dig any deeper. If possible,
use sections of culvert or concrete rings to reinforce the walls as
you dig, to prevent collapse. These can slide down the walls as you
dig deeper.
When finished, place a layer of gravel at the bottom of the well,
if possible. It is generally suggested that you disinfect a well before
using, or after possible contamination, with a chlorine solution (which
you can make from bleach).
Wells can be improved for safety, sanitation, and longevity. Place
a cover on the well so that people and debris cannot fall in. Always
use a clean bucket to draw water from the well. If people physically
enter the well, there is a danger of the well collapsing on them,
or them causing contamination of the well.
If possible, line the walls of the well so that the walls do not
cave in or shed soil into the water over time. You can use bricks
and mortar, concrete rings, or whatever sturdy, non-toxic materials
you have available.
You can also install a windlass or handpump, to make it easier to
raise water.
To avoid puddles of water forming around the well, which cause mud
and can breed mosquitoes, you can install a stone “apron”
which will drain water away from the well.
Well notes:
Lifewater Canada, at http://www.lifewater.ca/Section_Tutorial.htm,
has a 100 page manual on wells available online, as well as other
information on water.
Waterhole: How to Dig your Own Well, by Bob Mellin covers drilling
well with a hand-auger.
Wells and Septic Systems, by Max and Charlotte Alth
Springs
Springs are generally an excellent source of clean water. However,
in some situations water from a contaminated surface source can travel
a short distance in an underground channel and only appear to be a
spring. You may want to check.
Springs appear in areas where the water table reaches the surface,
generally on the side of a hill or other slope. The water is forced
out to the surface. Check maps of your area for known spring sites.
Also, spring-fed streams may be fuller in the dry-season than rain-fed
streams. If you can identify spring-fed streams, you can follow them
back to the source.
Development and Refugee agency handbooks generally recommend “improving”
springs to prevent contamination. This may or may not be suitable
for your needs depending on the population density of your area, the
nature of the pathogens present, and other factors.
This “improvement” usually means encasing the spring
itself in a container (usually concrete) to prevent direct access
by humans or other animals. The water comes from a spout which is
installed on the container. This way, pathogens can’t be deposited
into the spring itself, where they might breed. However, there are
some less invasive methods described in WELL Technical Brief #34:
“Protecting springs: an alternative to spring boxes” (see
notes).
Rainwater and Snow Collection
Rainwater is a great source of clean water, so try to collect as
much rainwater as possible. Allow the first runoff after a long dry
spell to flow away, to clean dust and such from the roof or catchment.
According to UNEP the ideal roofing for a water source is smooth, dense
and non-toxic. They suggest that this includes “corrugated aluminium
and galvanized iron, concrete, asphalt or fibreglass shingles, tiles
with a neoprene-based coating, and mud”. They suggest avoiding
the use of “natural” materials such as thatch as a source
of drinking water, because such roofs may attract insects and rodents,
and yield contaminated and discoloured water. They also suggest that
flat ground surfaces, such as runways, can be used as long as they
are fenced off to prevent access and contamination from human and
non-human animals.
One millimetre of rainfall will yield about 0.8 litres of water per
square metre of catchment area. (In US imperial units, that means
that each inch of rain will give about 6.4 gallons per square yard.)
Loss is due to evaporation, and varies by climate. In cooler climates
you will get closer to a full litre per square metre (or 8 gallons
per square yard).
Water storage containers should always be covered to prevent contamination.
Also, pipes or openings to the tanks (except the faucet) should always
be screened to prevent the access and breeding of mosquitoes or other
insects. See the illustration for examples of several rainwater
catchment options.
Snow can also be used as a source of water, but should be gathered
from clean sources away from animal traffic (including humans) to
avoid possible contamination. Ten portions of snow will yield about
one portion of water, so if you are melting snow in a container on
a fire for drinking, keep topping up the container so that the water
doesn’t boil and evaporate. (Unless you believe the water is
suspect and want to boil it.) Don’t try to melt snow in your
mouth. In cold climates, this will rob your body of too much valuable
heat. If water is cold, just sip it, don’t gulp.
Remember that snow is only as safe as the water it comes from, so
treat it if you have any doubts.
Rainwater collection notes:
UNEP, Sourcebook of Alternative Technologies for Freshwater Augmentation in Small Island Developing States, http://www.unep.or.jp/ietc/Publications/TechPublications/TechPub-8d/
Surface Water Collection
When collecting water from surface sources, try to check for possible
sources of contamination. Contamination can come from agricultural
and industrial chemicals, soil erosion (especially in areas with industrial
farming and logging), feces from humans and animals, garbage, from
humans or other animals entering or washing in the water and tracking
in contaminants or pathogens, or from dead animals in the water. Development
and Refugee agency handbooks offer a variety of suggestions on how
to prevent the contamination of surface water.
These include fencing ponds and rivers to keep farm animals out and
discouraging people from entering or swimming in sources of drinking
water. Generally, they recommend keeping swimming/washing and drinking
water sources separate. To prevent the need to enter water, they suggest
building ramps or platforms, into the water, which also reduces erosion
in places where soil may run into the water.
Lively, bubbling streams or rivers with rapids and white water are
great sources of drinkable water. The aeration purifies it in a distance
of about 10 m.
Surface water notes:
WELL Technical Brief #47: Improving Pond Water
Survival Sources
Dug Still
One of the simplest ways to get water in a dry area is to dig a
hole, as shown, and place a container in the middle.
Then place a clear plastic sheet over the hole, with a stone in the
middle and weighting on the edges. The water that evaporates out of
the soil will condense and drip into the container. You can also use
a flexible hose to suck water out of the container. You might be able
to add succulent leaves or vegetable matter into the hole, to provide
more water for evaporation.
Look for the best spot to dig a hole like this, such as depressions
or valleys, areas with green plants, or areas which look damp. However,
also try to place the still in a sunny spot, so that you get more
evaporation and condensation.
Transpiration
Trees and plants naturally release water through their leaves as
they breathe. You can put a transparent bag, such as a clear garbage
bag, over a branch as shown, below and seal it air tight. Water will
condense and collect at the corner of the bag. You can make a small
hole or slit to drain the water, and then tie or seal it shut again.
Don’t bag the branch for too long in hot weather, or it may
die. Do not use poisonous plants.
Dew and Condensation
In the early mornings or in cold, sheltered spots, you may be able
to find dew on rocks, metal and vegetation. Use an absorbent cloth
to sponge it up, and then wring it out into a container. You can tie
cloth around your ankles and walk around in dew-covered grass before
sunrise.
Water in Plants
Bamboo, banana and plantain trees, palms, and other plants contain
water in their stems that you can access by cutting them. Consult
local knowledge or books, and don’t kill a tree unless you have
to.
Observing other Animals
Watch animals like flies, mosquitoes, bees, doves and pigeons. They
need to travel to sources of water regularly to survive, and you may
be able to follow them.
Survival water notes:
Tom Brown’s Field Guide to Wilderness Survival, Tom Brown Jr.
US Army Survival Manual: FM 21-76
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