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.
Per Webster’s 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.
In
my Great Aunt’s 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 barrel.
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.
Once
you have a container, simply put the barrel beneath where the
rainwater runs off your roof and you have started harvesting.
Look
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 don’t
like big bond issues to pay for new water treatment plants. There
are lots of possible reasons.
With
me 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.
If
your 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.
Most
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 tanks?
The
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.
As
you 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 – 75,000 liters).
My
tanks are about 2,000 gallons each (i.e. 7,570 liters each).
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 xxx. Raising
your rain barrel is the
quickest and cheapest 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 rain.
However,
rain barrels can and should be used to augment your watering.
This
will cut your watering bill and be better for your grass.
I
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.
But
remember, rainwater is still free. The constraint is the cost
of the tank.
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.
I
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.
So
if 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 depth.
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 50°F to 70°F 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 called potable water.
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?
First, 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 for 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 rain.
Make 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.
And of 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 rainwater potable?
Several 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.
http://www.harvesth2o.com/uv.shtml
Please also check with local officials on what is allowee.
20. Are there differences in the efficiency of roof materials in capturing rainwater?
Yes, below is a table listing the differences. A good article on this is The Capture System.
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% runoff efficiency
For a bare soil roof assume a 75% runoff efficiency
For a grass roof assume a 17% runoff efficiency
21. Do other countries require rainwater harvesting?
Yes. Australia is a great example of where harvesting rainwater is required in several states on new construction. A good article on this is Harvesting Rainwater Downunder.
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.
