Rendering roof runoff potable

I've been experimenting with harvesting rainwater by use of portable cisterns and exploitation of naturally occurring drainage patterns...well, actually, I have been moving a 45 gallon trash can under places where water runs off the roof. Fills up fast here in the tropic rainy season.

In looking for information about the potability of rainwater, I stumbled upon a publication from academics that indicates that rainwater is actually poison falling from the skies, and needs to be filtered to 5 microns for removal of lead, and 1 micron for bacteria and parasites.
So much for catching raindrops on my tongue.
This level of filtration is well within reach of my msr miniworks and similar devices, but chlorine, iodine and uv filtration seem to be ruled out.

If the rain is as severely polluted as this, why aren't we all dead?

This product http://www.rei.com/product/890899/sawyer-mini-water-filter-package-of-2 filters to 0.1 micron,and I don't believe it is unique. Giving your reference a very quick read, it looks like most of the contaminants comes from contact with roofs

Chemicals such as Lead are dissolved in the water and CANNOT be filtered out.

Distillation is the only way to remove them and that will not remove many of the lighter molecules totally, but perhaps bring levels down to an acceptable level.

Pop along to your local water treatment plant or your water utility and ask them, try and get a tour of the plant and you will see what is necessary.

My understanding of roof runoff is that it varies based on where you live and your roof.

Some folks let the first few minutes of rain go into the ground and then collect the runoff. Some (and I don't advise this without lab testing at least once) do not treat the water collected this way before drinking it. Others treat with filters or chemicals, and I'm sure there are situations where roof runoff cannot be treated economically.

I would suggest either using roof runoff for non-potable purposes or springing for a lab test of both the first water that comes off the roof and water that comes off after five minutes or so of a good rain, to see what you're up against.

The CDC thinks that lead can be filtered out of water.

From the CDC drinking water article


You may also wish to consider water treatment methods such as reverse osmosis, distillation, and carbon filters specially designed to remove lead. Typically these methods are used to treat water at only one faucet. Contact your local health department for recommended procedures. If you want to know more about these filters, please contact NSF InternationalExternal Web Site Icon, an organization for public health and safety through standards development, product certification, education, and risk management. Remember to have your well water tested regularly, at least once a year, to make sure the problem is controlled.

The NC study in the OP did not mention a control harvest to collect rainwater without the roofing product contamination. Raindrops form around high altitude particulates, some of which are contributions from coal-fired industrial plants, jet contrails, volcanic eruptions and angel feathers. Without intervening roof pollution, acid rain has produced a lot of crystal clear lakes in the Adirondacks: crystal clear because they are lifeless due to elevated pH. Reinforces the recommendation for water analysis. I believe government subsidies are available for rainwater cistern installation in the Florida Keys, to reduce demand on the pipe from the mainland-maybe this is a partial answer to the increasing scarcity of water in the West.

Biosand filters and roof water.

Lots to consider. Each roofing material requires thought.

http://slowsandfilter.org/ssf_faq.html#roof_water

Nursemike, you are confusing two styles of filtering.

Physical filtering to remove particulates, which will not work, and exposing the water to absorbents in a bed which, with the correct absorbent, activated carbon, ion exchange resin, etc. will work.

The OPs link statement that filtering to 5 microns will remove dissolved lead is just plain wrong. Very easy to test. Try adding some food colouring dye to the water and see if a particulate filter removes the dissolved material.

Presuming that we are talking about the collecting and drinking of rainwater in an emergency, rather than under normal conditions, then I would not worry overmuch about lead in the water.

Lead is a long term chronic poison and unless present at most improbable levels is of little short term concern.

Presuming that the roof is not made of lead, then the only source of lead in the water is industrial air pollution.

Whilst times are normal, I would drink city water, or deep well water, or bottled drinking water.

In a short term but serious emergency I would drink roof water after boiling or chlorinating to kill germs, and not worry about lead.

In a long term TEOTWAKI situation then industrial activity and the pollution that it produces would cease within a few months.

When collecting roof water, it is desirable to discard the first flow of water from the roof as this will be contaminated with bird droppings, dust, and leaves etc.
Automatic devices to do this can be improvised.
If water be very scarce, then this first flush of water can be put on the garden or used to flush a toilet.

Rather than investing in some system to purify roof water from lead or whatever may be up there, why not collect it from something other than your roof? Like use a couple of big tarps to collect it? This is assuming you're not using rain collection as your primary source of water for long term.

Interesting comments so far. But I have got to think that there are MANY places in the world where rainwater is still fresh and clean. I really can't imagine that all of the world's rainwater is "poison".

It makes sense that rain is "suspect" if you are downwind (in the path of storms) from major cities with air pollution and industrial pollution.

Rainwater has also been implicated as a potential danger after nuclear explosions (atmospheric), where there is radioactive fallout. For example, the types of tests that were done in Nevada (USA) back in the 1950's. This is because the fallout radiation gets on dust particles. The dust particles are lifted into the atmosphere, and they will be collected when raindrops are condensing in clouds. So scattered "high spots" of radioactivity can occur in the rainfall downwind of an atmospheric nuclear test.

But I would have to think that rain that falls on the coast, from clouds that formed over the ocean, is probably very clean. However - what happens when it falls on your roof, and then flows through the gutter ... that's a good question! Hahahaha!

This topic is not just "random" for me. There's a good chance that I will be moving to a remote location in the next 12 months. And it is very likely that I will be using rainwater as one source of fresh water for drinking and bathing.

Pete

I was out at dawn this morning cleaning my car windows (with the drought conditions here is SoCal i have not washed my vehicle in months). I believe that all the crud and dirt on the windows was deposited there by dew, no roof runoff, etc. I think I would boil before imbibing.

I an right on the coast,but rain reaches us from the west or northwest, and probably does pick up some pollution, but I imagine it is even worse further inland.

one passive "first water exclusion" system that I though was pretty well designed has several (depending on the height of your house) vertical stand pipes of large diameter 4" or so PVC connected to your eaves system...the pipes must fill first before the cascade overflow at the top then goes on to the next pipe then to storage totes... a clean out plug at the bottom allows removal of large debris not screened by the eaves, and left slightly ajar(or drilled with a small hole) to allow water to slowly drain from the stand pipe after the storm

State rain water/ gray water harvesting regulation

Makes sense that the government should regulate rainwater collection, as they regulate private wells and public water supplies. OTOH, makes me wish that the patriarchs had added a "right to keep and drink rain water" amendment.

I have resolved not to think of rainwater as poison falling from the sky, but to re-conceptualize it as freely available water that requires no more purification than does the water from a mountain brook.

I call it the "rain barrel half-full" approach.

Lots of vendors out there, too, including a seller of bottled rainwater .

"I have resolved not to think of rainwater as poison falling from the sky, but to re-conceptualize it as freely available water that requires no more purification than does the water from a mountain brook."

Here's one simple thing that you could do.
and to be honest - I will probably do exactly the same thing.

Collect a gallon of rainwater - by whatever method you choose.
Clean a large saucepan - so that it is spic and span.
Pour the rainwater in the saucepan, and heat slowly on your stove.
Allow the water to boil away completely, and take a look at what is deposited on the surface of the saucepan.
That might be a simple place to start - to see how clean the rain is.

Let us know if you find anything. I am curious.

Pete

That would show if dirt was in the water but it wouldn't show any chemical with a boiling point close to that of water.

Phaedrus - true.
It's not a perfect test. The results are very useful, but they don't tell you everything.

I'm open to the idea of other simple tests, or even a water testing kit. I wonder if there is such a thing (simple and inexpensive).

There's also well water testing kits and home water purification systems if you intend to use it for drinking. Personally, I'd use it for filling the toilet tank during an outage, and landscape irrigation during normal times. Unless you live in an area with unreliable utilities and plenty of rainfall, I don't see breaking even on cost of a home water purification system.

i collect rain water from a downspout for garden use and later in the Fall i run 55 Gallon drums of it into 30 Gallon drums in the basement for Winter house plants.
a screen over the drum keeps out the hunks and chunks from the nearby trees and a few goldfish eat any bugs that might use the water to hatch in.

Well said. The break even would depend on the alternative water system costs, and, except in USVI and Key West, selling a house that operates on rainwater harvesting might be tough.

OTOH Fresh water supplies are dwindling, demand is increasing, and the states surrounding the Great Lakes have formed a pact to prevent exporting lake water to other states. Infrastructure like water and sewer lines are deteriorating, and electric generation is becoming problematic due to disenchantment with atomic energy systems. Perhaps the home of the future will need to be self sufficient in water, sewer, and electrical service.

Reverse Osmosis Water Filter installation kits are available to make potable water.

http://www.amazon.co.uk/iSpring-RCC7AK-U...is+water+filter

https://www.youtube.com/watch?v=sDhC9XMKLPA

I would be quite worried though if the rain water was worse than this;

https://www.youtube.com/watch?v=a6uK3YaloXs

Not forgetting your daily medication dose of Fluoride to shift you leftward on the IQ Normal distribution curve of course.

My science is old and rusty: as I understand it, reverse osmosis means using pressure to force water molecules through really small holes/semi-permeable membrane against the normal flow of lower concentration to higher concentration. Does that men that pump water filters like the mini-works, or gravity filters like the Sawyer are committing reverse osmosis?

they're not reverse osmosis , if they were that fact would be heavily advertised,
A "manual reverse osmosis desalinator (MROD)," costs from one to two thousand dollars (katadyn)
Also

They're microfilters

Check out the Berkey Water Filters.

http://www.getberkey.com/

Injecting life into an old thread.

I moved to Brazil. A permanent change for me. We are now using rain water for everything. Tropical rain is very heavy in the afternoons. it is collected in large plastic tanks that sit on the roofs of houses. There is no filtration or treatment.

Wow! What prompted this move? What do you think so far?