"I have city water. Why should I catch rain?"
question! After all, city water isn't
bad, right? Well,
okay, some city water is horrible, but let's say your
city/county water is reasonably clean. Why bother with
Because the water you
depend on may not be dependable. Why? Because
municipal water systems operate with electricity and pump water
to you under pressure - no electricity, no pressure, no water.
So if your electricity is interrupted, you lose lights
"Oh, but that happens
so rarely." Exactly! The point is that it
does happen and can happen with no warning. How long
can you live without water? Right again, not very long. What
would you do if your water supply was cut for a week? For a
month? It could happen.
So why risk the safety
of yourself and your family, by being totally
dependent on a water supply that could shut down tomorrow, or
today? You can secure your own water supply easily by
installing - or having someone install - a simple rainwater
harvesting system that will give you clean water all year, for
"Can I use my
roof?" Many people do, but water quality depends on
what kind of roof you have and what you intend to use the water
for. If you want drinking-quality water, good catchment
surfaces include concrete, clay tiles, slate, sheet steel with
baked on enamel, polycarbonate and fiberglass.
Galvanized metal and
asphalt shingle roofs will produce water that may be
suitable for washing but not for drinking. These roofs
contaminate rainwater with zinc and petroleum chemicals
respectively. However, solutions exist.
"Where do I
start?" Right here, by first answering a few basic
Will this be a backup
or a primary water supply?
A backup system is your
Plan B, your emergency water supply for those times when your
main or primary system stops working. It is designed to provide
as much or as little water as you think appropriate, until your
primary supply is operating.
A backup system can be
scaled to provide only emergency water - drinking,
some washing, bathing - or it can be a parallel primary system,
with as much water as you normally use. In this case, it can
become your primary water supply (since the water is free) and
your city water can be the backup! Your choice.
How much water do you
need this sytem to supply?
Many people have little idea how much water they use each day -
it just goes down the drain and toilet, unaccounted for. A few
years ago, the average US home flushed about 40% of its
drinking-quality water down the toilet, just to get their waste
out of sight. Some of us like to take long, wasteful showers,
or soak in a bathtub with many gallons of water. Calculations
You will have to keep
track of your water use for a week or so. Count the
gallons you use for a week and multiply by 52. That's what you
need for a year. Correction: That's what you USE in a year. You
probably need much less. See Calculations.
What will the water be
A safe amount to calculate for drinking
water is a gallon per person per day, or 365 gallons per year.
A relatively small system can supply this amount. However,
drinking-quality water requires that all materials that come in
contact with the water are relatively inert - they don't
contaminate the water with chemicals.
In order to supply a home with
water for everything, it is possible to install two
systems: one for washing and household use, another only for
drinking. This way, the strict requirements for drinking water
need not apply to the larger system.
Do you have space for
a storage tank? Need a permit?
Water storage tanks
tend to be large - about 6' to 8' in diameter and from 4' to
10' high or more. Things that large tend to attract attention,
especially when they arrive in your neighborhood.
Check with your local
officials to be sure that you can have the tank in
your yard. You don't want to find out later that you
Do you have a budget
for this system? How much?
The storage tank will be
the most expensive part of the system, unless you are
installing a new roof. Polyethylene tanks cost between $0.50
and $1.00 per gallon capacity new.
Will you install your
system or will you have it
you hire someone to install your system, locate an
experienced person, and expect to pay $25-$40 per hour.
Skilled labor (example: auto mechanic - $65 per hour) is
money well-spent, IF you get what you pay
If you are handy with tools
and understand how a rainwater system functions, you may be
able to install your own, saving you money. However, be
realistic about your skills - this is your home's water supply,
not a drip irrigation for your tomatoes.
Will you use an
existing roof or surface, or will you build
Ah, the tough question. Well, many people have
asphalt shingle roofs, because they're cheap. Asphalt is a
petroleum product and smells like, well, oil. So does the
rainwater coming off the roof - it's contaminated with asphalt
and unsuable for drinking.
You can use that water for
washing, but personally, I don't like to brush my
teeth with it. Try it and see what you think. Putting on a new
roof may be out of your budget, so what can you do?
Look at the photo at the top of this
page. I installed this system to collect water only
from the fiberglass patio roof, because the house has an
asphalt shingle roof. I even put aluminum flashing in two
house-roof gutters to block any water from going over to the
patio roof catchment.
If you don't have a suitable
catchment for drinking quality water, you have several
options. You can create another roof or catchment surface. You
can resurface part or all of your existing roof (expensive).
You can create a surface
catchment system - collecting rainwater at ground
Climate change may force all of
us to consider a backup water system. Global warming,
and the resulting disturbances to weather patters, will impact
the availability of water, even in places where water is now
plentiful. More on this here.