Yet another reason to catch the rain before it hits the dirt.
The below study, a first of it's kind, begins to examine the buildup of a few drugs in soils over time. It is well known that there are hundreds of contaminants not monitored by the EPA in our water supplies. This study takes it one step further and starts to examine them in the soils and how long they last. Much more research needs to be done in this area to help us understand how to remove these harmful contaminants before they enter our food system, but at least we are starting to understand that they just don't disappear because we flush them down the drain.
Health Problems Uncovered By New Research - Wastewater Reuse
Of course, capturing rainwater and using it is one way to ensure you are not watering your garden or drinking water with these contaminants.
I have build a house with a metal roof, a rain water
collection system which eliminates the first run off and which then
drains into a 25,000 gallon double cistern under the garage. There are a
few filters which progressively smaller diameter , the last one down to
one micron absolute. As most bacteria or spores are > 1 micron, I
assume that a UV light is not necessary (viruses are not a real issue
for rain water).
As there will be no or a very small amount
of minerals, I believe I won't need a carbon filter either. Are my
assumptions correct in your opinion? To clarify, the water is for
domestic and for garden use.
John, first thank you for the question. Unfortunately rainwater will have active bacteria in it in almost
100% of the cases. This bacteria needs to be taken care of either
with filtration or purification.
The norm for rainwater systems is UV or Ozone. Chlorination, RO,
and distillation are also options however, not commonly used in
rainwater systems. A 1 micron filter will not remove all bacteria, but most. I have read publications by the CDC that it needs to be a .3 micron to remove almost all bacteria. Of course this would not remove viruses.
The linked article below gives a good overview
of the various options. I have also linked a book below that is
very useful, with great charts and tables.
As far as carbon you are correct. I only recommend them when more
removal is required.
I recommend .25 micron (sediment removal), a 5 micron (most bacteria and dust), a granulated carbon filter (chemicals, chlorine, bad smells and taste) and finally a UV light (disrupt DNA of bacteria making it harmless). This combination removes bacteria, most viruses, and cysts.
This rainwater harvesting (RWH) system, with an above-ground, 7,500 gallon (usable) poured-concrete cistern, used for both potable and nonpotable purposes, was designed and constructed in 2001 as an integral part of a new single-family home in Key Largo, Florida. Rain is collected from a 1,700 square-foot white Galvalume roof and gathered in six-inch copper gutters with spash shields at roof valleys for occasional heavy downpours. Copper plumbing is used throughout the house as well. Read full article>>
Question and Answer Session with John
John, first thank you for publishing the article on your home system. It is a great reference for those interested in following in your footsteps and living on rainwater and solar.
One of the questions, that I have and I am sure many of the readers will have is - why? Cisterns were always in the Keys, so it was a natural to build when we were building our new home.
Was 7,500 big enough? No, it is not big enough. Budget and space prevented us from putting in a bigger one. I have never met anyone that has a cistern too large. Would have liked to go at least 50% larger.
Why concrete? The house is made of concrete and it is part of the house structure. Also it neutralizes acidity from rain and lastly it is widely available in our area.
Why an 8" cistern wall? That is what the engineer advised.
What is a rubber "dam" gasket? It is a piece of rubber about 1/2" thick and about 8" wide comes in a roll. It is put between the floor and wall to prevent any leakage. Half of it is put in the base around the edges when it is poured and the other half is put into the wall when it is poured.
Do you use greywater? No, I wish we did. Regulatory barriers were a big issue in building green. Greywater would have been another barrier and we did not have the time.
If you would to do it again, what would you do differently? I would have smaller downspouts, design some way to move water between sides of the tank, consider using a floating extractor, a low level cut of switch to prevent the pump from burning out and re-analyze newer filtration methods.
If you have any questions, please submit and John will answer them to the best of ability.
In addition to its effects on
biological and chemical processes, the variability of pH affects our decisions
in domestic water usage. High-pH water often tastes bitter and may be an
indication of the scaling potential of the water. Low-pH water may lead to the
dissolution of pipes, particularly copper pipes. The EPA classifies pH under
unregulated Secondary Drinking Water Standards and recommends a range between
6.5 and 8.5 pH units.
The term "pH"
refers to the potential of hydrogen. The scale measures the logarithmic
concentration of hydrogen ions (H+) and hydroxyl ions (OH-), which constitute
H2O. Because the scale is logarithmic, a change in pH by a factor of 10 results
in a change of one unit on the pH scale - the pH scale ranges from 0 to 14 and
is a measure of the acidity/basicity of water. A neutral solution, with a pH of
7.0, is achieved when the activity ofH+ and OH- is balanced. Water that has
more free hydrogen ions (over 7) is acidic and water that has more free
hydroxyl ions (less than 7) is basic or alkaline. Acids lower the pH of a
solution and bases raise the pH.
Well water is typically high
in ions (both positive cations and negative anions) such as calcium and
magnesium (the "hardness" minerals), sodium, potassium, nitrate,
chloride and sulfate. The presence of these ions decreases the activity of the
H + ion and increases the activity of the OH- ions, causing the water to be
higher pH. Well-water pH is a function of the minerals taken into solution as
the water moves through rock strata. In Santa Fe, our municipal water, which is
commonly a blend of sources, has a pH ranging from 7.04 to 8.21, with both the
low and high ranges occurring in Buckman Well Field water (2010 Water Report,
Sangre de Cristo Water Division).
The term "alkaline"
should not be confused with the term "alkalinity;' which refers to the
"buffering" capacity of water, or its ability to resist or
"buffer" changes that would make the water more acidic. The main
sources of natural alkalinity, which limits swings in pH levels, are rocks
containing carbonate, bicarbonate, and hydroxide compounds. Borates, silicates,
and phosphates may also contribute to alkalinity.
Conversely, granite, which is
a common aquifer in the Santa Fe foothills, has few minerals that contribute to
alkalinity. Areas rich in granite have generally low alkalinity and therefore
poor buffering capacity. We sometimes see low pH in water produced from
fractured granite aquifers.
In general, reverse osmosis
(RO) water, although extremely pure, has inherently low pH. This is not because
of the RO process per se, but is a function of the fact that RO water has such
low total dissolved solids, or mineral ions, that it has little or no buffering
capacity. The easiest way to raise the pH of RO water to a more palatable, and
less corrosive, pH level above 7.0, is to pass it through a food- grade,
NSF-certified calcium carbonate (calcite) media filter. If you buy bottled
water, most of which is mass-produced by RO, you can bet that the pH has been
Stephen Wiman has a
background in earth science (Ph.D. in geology) and is the owner of Good Water Company
in Santa Fe.He can be reached at
505-471-9036 and skwiman @ goodwatercompany.com.
Much is being written about 'Tap to Toilet' these days as a
new water source for municipal water providers.This type of tap water is your old toilet water cleaned and sent back to
the tap. As you can imagine these are
big, costly water infrastructure projects.
In an effort to seek viable alternatives California
announced a couple of years ago a project, whereby used water would be cleaned
into drinking water. The project was shelved
due to public outcry. It is back.
In August of 2010, the San Diego City Council launched a
pilot program to do just that - 'Tap to Toilet'. The public remains skeptical about the cleanliness
and drinkability of the water and there are many that have raised concerns in
the treatment and purification of the water from waste to potable.
The term 'Toilet-to-Tap' angers and scares the public very
easily. Originating from Gerald Silver, an angry Encino homeowner's association
president who used the phrase in 1995 during a debate over it in Los Angeles;
consequently the industry prefers to use the term IPR (i.e. Indirect Potable
Reuse ) instead.
Typically the IPR process for treatment of water involves a
multi-phase filtration system broken down into many, many steps.During the first few processes, the water
passes through various screens and sedimentation, including beds of anthracite
coal, which removes most suspended solids from the water. According to many experts
familiar with the process, the water at this point is safe for irrigation and
other non-drinking uses.
In fact, many cities across the United States and around the
world use this processed water already for irrigation of parks and golf courses
as well as other industrial uses.Of
course, to be ready for drinking it must be further filtered and cleaned and
meet EPA Drinking Water Standards.
With over 90% of its drinking water imported, the growing city
of San Diego is facing a water crisis - it is only a question of when.A recent federal judge's ruling that may
limit the amount of fresh water that can be pumped from the San Joaquin River
Delta in an effort to protect the delta smelt, an endangered fish is just one
thing that could throw the whole water supply equation totally out of balance so
the city is at the forefront where IPR may become a reality.
It is an emotional issue and consequently some arguments are
not entirely based on reality.Many,
many communities today are using water that was used before.Unless you are fortunate to be near a fresh
the source of water or rely totally on well water the chances are very high that
the water you are drinking partially came from a waste water treatment plant
To make this water drinkable it is mixed with raw water and
then large plants are built to process it before it gets to the tap (i.e. new
treatment plants are usually hundreds of millions to billions of dollars
depending the on size of the plant).There is a gigantic industry supporting water treatment due to the
monies and potential profits involved, so you can be sure it is going to happen
- it is just a matter of time.
The other 'Tap to Toilet' that is not getting as much
coverage in the press these days is piping your used bathroom faucet water into
your toilet and reusing it a second time.Not very exciting nor very expensive.Given toilets are the biggest water users in a house the potential water
savings are enormous.But this is of
little interest to water providers as they make money selling 'new' water; not
promoting reuse of water in the house two or three times.
These inexpensive devices direct the water from your faucet
that would normally go down the drain to go instead to a basin hooked to your
toilet.To avoid the 'tap to toilet'
controversy these are sometimes referred to greywater toilets; although the
toilets have nothing to do with the installation - it is the water source that
is changed.So instead of flushing clean
drinking water down the flush you are flushing slightly used water - saving literally
tons of water over the life of a flush and billions of gallons if implemented
across the United States.
There were an estimated over 350 million public and private
toilets in the United States and growing.That is a lot of gallons flushed no matter how you look at it. In fact,
residential toilets account for about 30 percent of all indoor residential
water use in the United States and faucets account for more than 15 percent of
indoor household water use.
So marrying the tap to the toilet just makes sense.So why is no one picking it up and pushing it
as a great inexpensive solution.Especially, since the US government is projecting that over the next 5
years water shortages will occur in nearly every state.
My bet is on the money.Inexpensive, highly distributed, cost-effective approach to saving water
versus highly-costly, centralized approach - my bet is on the latter just due
to the dollars involved.But my heart is
on the former as a much better solution for us all.
I recently posted an article on my website dealing with Solar
Disinfection. Dr.Anumakonda Jagadeesh was kind enough to allow me to
republish this article in full with tables included in the complete
article. An excerpt of this article is below.
One might wonder
how Solar Disinfection and Rainwater Harvesting
are related. Through the website I get many, many questions on how to
filter rainwater. These questions come from readers around the world as
well as organizations interested in providing low-cost, low maintenance
drinking water systems. Solar Disinfection is one method that has
proven to be effective as Dr. Jagadeesh research again shows. His
low-cost design is perfect for locations with lots of sun and do not
have access to clean, purified potable water.
8 seconds, a child dies from water related disease around the globe.
50% of people in developing countries suffer from one or
more water-related diseases. 80% of diseases in the developing countries
are caused by contaminated water. Providing safe drinking water to the
people has been a major challenge for Governments in developing
countries. Conventional technologies used to disinfect water are: ozonation, chlorination and
artificial UV radiation.
Treatment to control waterborne
microbial contaminants by exposure to sunlight in clear vessels that
allows the combined germicidal effects of both UV radiation and heat has
been developed and put into practice. Though 6 bottles were used in
the system(each of 1 liter capacity), larger units with up to 100
bottles can be designed. The unit destroyed 99.99% of bacterial coli
forms both in well water and waste water samples in 5 hours.