1. How do you harvest rainwater? As amazing as it
sounds, this is a question that comes up often. It must be theword
harvest that is causing the confusion.
dictionary harvest is defined as 1) to gather in or 2) to accumulate
a store of. Consequently to harvest rainwater means to gather it in.
Great Auntís house in Maine, this was done with an old wood barrel.
It was put beside the house and rainwater drained into it. We would
use this water to drink, clean the dishes and everything else you
can think of. Today it can still be caught with barrels, large and
small, but I would advise against drinking it straight out of the
2. Where do you get the water? Fortunately it
comes FREE from the sky. They still have not figured out a way to
privatize rain yet. Although I am sure someone is actually thinking
about those air space rights.
3. What is the best way of harvesting rain? Catch
it in anything that holds waters. Many landscape or garden stores
can tell you where to buy barrels. Here in Austin we have a wide
variety, with some selling new barrels and other selling barrels
that have been recycled. In the Austin yellow pages I found them
by calling a few landscapers and even one of the gutter installers
advertised rainwater collection. Some cities offer incentives, so
also check with your local water company.
you have a container, simply put the barrel beneath where the
rainwater runs off your roof and you have started
for barrels that have a faucet attachment where you can attach a
hose to use the captured water for your yard.
4. Why should I harvest rainwater? Good question
and probably the answer is going to be different for different
folks. Some will like the idea of not paying the utility company for
something that is FREE. Or maybe it is because rainwater is
typically better for the plants. Or it could be that you donít like
big bond issues to pay for new water treatment plants. There are
lots of possible reasons.
it was a little bit of all the above. But also it was a project I
could do personally and knew it would have a net positive impact on
the environment. My system makes me feel great when I am out
watering or just looking at our yard.
5. Do I need pumps to harvest
rainwater? Maybe. If you
just have a small barrel and you are using an attached hose
or soaker line, no pump is likely required. If you have a barrel
or tank that is above ground level by a just a few feet, and you
are on a flat piece of land, and have a small yard; probably no pump
will be needed.
tank is at ground level and you need to move the water up any slope
then you will likely need a pump.
However, sometimes you can get enough water pressure in a
closed-looped water collection system to supply the pressure
required, even to drive a sprinkler system. Consult a local
specialist to determine what is going to work for you.
6. Can I use drip irrigation or soaker hoses with a
rainwater? Yes, but I
recommend you install an inexpensive line filter.
irrigation stores sell inline sprinkler filters. This is a simple
device that screws into the lines prior to your irrigation system
and cleans out the large leaves and other stuff (i.e. sometimes
referred to as particulates) out of the water so it does not clog
your lines. Check out the vendors page for
information on several inexpensive filters.
7. How big a yard can I water? It depends,
simple question with no simple answer. Can you have rain barrels at
various places around the yard? How much rain can you capture? What
type of plants do you have? How much do you want to spend on
Austin Wildflower Center has 2 - 25,000 gallon (i.e. 7.5 - 94,625
liters) tanks and 3 cisterns. They estimate they can capture up
to 300,000 gallons (i.e. 1,135,500 liters) a year and they
estimate their system meets 10-15% of their annual needs. The
Austin Wildflower Center covers 279 acres and displays over 500
species of native plants and has become a popular destination for
knowledge-seeking gardeners and nature-loving tourists.
can see, systems can be very large and water an extremely large
area. It is just a matter of how much you really, really want to
capture and how much you want to spend.
8. How big are rain barrels? Thanks for the
soft ball question, I needed it. Rain barrels vary in size from a
few gallons/liters to about 100 gallons (i.e. 378 liters). Most
barrels are around 50-60 gallons (i.e. 189 - 227 liters).
Rainwater tanks run from several hundred gallons/liters to
many thousand gallons (i.e. 7,000 Ė 75,000 liters).
tanks are about 2,000 gallons each (i.e. 7,570 liters
9. I want more pressure, how should I raise
it? Raising your barrel or tanks or by installing a pump. Every
foot you raise your storage tank increases the pressure about
0.433 psi or less because of pressure loss due to friction (1 psi ~
3.21 feet of fresh water head). It generally takes only a few feet
to be able to use a hose or drip system, but it takes a lot to run a
sprinkler. Raising your rain barrel can be a quick and cheap way to
increase your pressure.
10. Can I water my grass with
rainwater? Yes, but grass
usually takes a lot of water. A typical lawn requires about 3,000
gallons (i.e. 11,355 liters) a month. This means you would need some
large tanks to hold the water, especially in drier climates.
Additionally, you would need a large surface area to capture the
However, rain barrels can and should be used to augment your
watering. This will cut your watering bill and be better for your
recommend before going with big tanks to water your lawn you look at
reducing your outdoor water consumption. Going to local vegetation,
drought hearty plants and then installing either drip irrigation or
soaker hose will reduce your water consumption. It will be less
costly, since you then need smaller tanks.
remember, rainwater is still free. The constraint is the cost of the
11. Is water quality a problem in rainwater systems?
Yes, as it is increasingly with all of today's water
systems. Rain water is generally free of harmful minerals and in
most cases chemicals, but can be adversely effected by air
pollutants and/or contaminated by animals in the catchment area. Due
to increasing levels of pollutants, city and bottled water providers
are increasingly turning to use of sophisticated treatment processes
and chemincals to ensure a quality product. Consequently, rainwater
for drinking should be carefully stored and treated prior to
consumption. Several technlogies exist for home treatment including:
ozone sterilization, UV and distillation.
remember as a small kid drinking rainwater straight out of the
barrel at my great aunt's house. But that was in very rural Maine
many, many moons ago. Now we have both increased pollution and
increased awareness. Pollution can add undesirable elements to the
water. And now we know that open water sources can harbor bacteria
and other health threatening organisms.
your rainwater is to be consumed by you or others (i.e. potable
water) then it must be treated. There are many ways to treat
rainwater (e.g. UV, Ozone, etc) and several articles on the
Harvest2o.com website go into these options in great
12. What is Ozone? Ozone is
activated oxygen. It is a natural purifier. Its clean, fresh scent
is often noticed after a heavy rain. Ozone is a powerful oxidant
that can safely be used to purify water. It is an alternative to
using chlorine. It is a stable, yet powerful, bactericide, viricide
and bleaching agent. It has been used in Europe to purify drinking
water for over 100 years.
13. How does Ozone work? Ozone was first
discovered in the 1840's. By combining the ultraviolet rays from the
sun, with air, ozone is generated. In 1906, the city of Nice,
France; built the first municipal water purification plant utilizing
ozone. Today, there are over 2000 plants worldwide using ozone to
purify drinking water. It is a stable yet powerful bactericide and
bleaching agent. It reacts chemically with other minerals and
compounds to remove or filter them out of the water.
14. How often should I replace my UV bulb? Most
manufacturers recommend about 9,000 or 12 months of continuous use.
The bulb may appear to be working (i.e. emitting visable light), but
may not be strong enough to emit at the required 254 nm wavelength;
so don't trust a simple visual test. Additionally, clean the glass
whenever you are replacing the bulb as any blockage can greatly
impair the effectiveness of the UV light.
15. Why don't I have to insulate a correctly buried
tank? The earth absorbs almost 50% of all solar energy and
remains a nearly constant temperature of 50įF to 70įF depending on
geographic location. If the tank is buried below the frost line than
the earth's natural heat will keep the water in the tank from
freezing. Care must be taken with the pipes to make sure they are
also below freezing level in the ground. Your local rainwater
harvesting supplier or contractor can tell you how deep the tank
needs to be buried
16. What is potable water? Potable water is another name for fresh drinking water.
Water of sufficient quality to serve as drinking water is often
17. What is LEED? LEED
stands for Leadership in Energy and Environmental Design. It is a
ranking system; whereby, buildings can be evaluated on a specific
set of criteria against other buildings. The result is a set of
points that rank a building's "sustainability". Water conservation
is one of the ranking categories in the LEED evaluation process. To read an article on
water and LEED.
18. I am researching metal roofing systems for a
client who is building a LEED residence and wants to harvest
rainwater. Do you have recommendations for metal roofing systems for
irrigation and/or potable water?
thank you Alicia for the question. Ideally there would be a roofing
material certified by the National Sanitation Foundation for potable
use, but there is none as of yet. NSF has certified some epoxy
coating but none for exterior use. You can find out more about these
materials at NSF Protocol 151.
as metal, galvanized metal, painted or unpainted with a nontoxic
paint, are common. Other roofing type materials include terra cotta
tile, slate, and fiberglass. Roofing materials should have as little
toxic material on it as possible, to reduce leaching into the
sure water does not sit on the roof for any length of time. This
reduces leaching potential as well. Of course for irrigation
purposes, almost any roof surface will work. Just keep the gutters
and water clean.
course put in screens on gutters, a first flush device and
filtration system to clean the water if it is to be used for potable
water. Every municipality is different on what is allowed, so please
check with local officials.
19. From a reader in Hong Kong, what sources are
available on utilizing UV filtration or ozone treatment to make the
sources exist. Below is a link to articles and the related links at
the bottom of the article refers to a company that has good papers
on this subject.
also check with local officials on what is allowee.
20. Are there differences in the efficiency of
roof materials in capturing rainwater?
For a tile/metal roof assume a
95% runoff efficiency
For a concrete/asphalt roof
assume a 95% runoff efficiency
For a gravel roof assume a 70%
For a bare soil roof assume a
75% runoff efficiency
For a grass roof assume a 17%
21. Do other countries require rainwater
Australia is a great example of where harvesting rainwater is
required in several states on new construction. A good article on
this is Harvesting
22. How do I prevent ice build up or ice dams
from forming and damaging the gutter system?
Depending on the angle of the roof, a roof snow scraper to
manually clean the roof or an electric roof de-icing cable like the
ones from EasyHeat in Connecticut or
the SRF-RG Commercial Grade Roof & Gutter Heat Trace Cable from
Chromalox in Pennsylvania.
23. What is the difference in filter screens
between mesh and microns?
Different measures for the same thing. Below is a conversion
from mesh to microns. These typically are used to tell you how small
the opening is in the filter.
24.When do I use a regulator versus a
valves are used in constant pressure situations and typically
installed prior to irrigation valves. Limit valves are best
installed with filters before them. Regulators are typically
installed after valves.
25. My water company uses a unit of measurement
CCF, what is this and how do I convert it to
water companies bill in gallons and others bill in CCF. CCF is 100s
of cubic feet of water. One (1) CCF equals 748 gallons of water. To
get gallons, multiply CCF by 748.