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Potable rainwater set-up cost  RSS feed

 
josh ober
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Does anyone have any idea on the price range of different potable rainwater set-ups? I imagine the purification systems are pretty pricey. Just wondering if having a well drilled could end up being more inexpensive?
 
wayne fajkus
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Capacity is biggest expense. If your longest average between rain is 3 months, you need 3 month holding capacity
 
wayne fajkus
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2500 gallon plastic tank is ruffly 1100

Groundfos pump is 600. But can cheapen down to 200

Filters prob 200 but you'd need it on well water, not necessarily on rain water.

Piping, gutter collection about 200
 
Su Ba
pollinator
Posts: 978
Location: Big Island, Hawaii (2300' elevation, 60" avg. annual rainfall, temp range 55-80 degrees F)
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Our main house system:
1- 10,000 gallon round corrugated steel tank with food grade poly liner and black woven poly tank cover (we also ordered the metal framing for over the tank that holds the cover above the water.) -- $2400 delivered but not assembled.
2- concrete donut to set tank on (we poured it ourselves) and a ton of sand for the bottom (sand safeguards the tank liner) -- $125
3- 5000 gallons of water, delivered, so that the tank liner could be stretched into proper position -- $150
4- flojet water pump $175 (small, but it does the job. They last us about 6 years. Our vog tends to corrode them, so they probably last longer if not in Hawaii.)
5- pressure tank. Cost depends upon how big you want it to be.
6- piping, depends upon how much you need
7- rain gutters or ground reservoir liner and pipes to catchment tank. All depends upon how much you need. This is for collecting the rain to send to the storage tank.
8- Filter. For potable water, a sediment filter and a carbon filter are usually needed. We don't make our water potable, so we don't have these. We just have a simple string filter set up for the water going to the pump.
9- UV sterilization unit. Cost depends upon your volume and flow rate. Most UV lamps need to run 24 hours a day. But there is one designed for off grid systems that doesn't. Again, we don't make our water potable, so we don't have one.

We purchased our equipment from Waterworks, Hilo, Hawaii. They have a website that you may wish to visit just to get an idea about what your system needs.
 
Corey Schmidt
Posts: 155
Location: Kachemak Bay, Alaska (usda zone 6, ahs heat zone 1, lat 59 N, coastal, koppen Dfc)
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It depends a lot on what you want.   If you are off grid and want potable water cheap, you can have that, assuming you have some roofs and live in an area with significant rainfall.  We get about 24" a year here in this part of Alaska.  At home I built a tank out of wire fencing, tar paper, irrigation pipe and 6 mil polyethylene sheet plastic.  Materials were about $30 for a 300 gallon tank, but this style could go all the way up to 1000 gallons without spending much more on materials.  We have a 12v dc rv pump (110v also available).  it cost around $100.  water goes right in the tank outside, and we use another pump to pump it inside, another $100.  Then a couple of filters, one for most of the house and an extra 0.5micron carbon block filter for drinking water.  That all adds up to around $300 but doesn't count the plumbing system in the house generally.   simplest system is just get a berkey filter, and carry water from a tank right under the downspout. Berkeys are not cheap but pretty reliable and long lasting, no electricity needed.   If you have building codes to satisfy, high water usage, and want 100% certainty of eliminating all pathogens that will cost you more.  I recently gave an estimate to a client of about $7000 to do a catchment system.  
What is there already is a roof with gutters, a home with plumbing system and pump and small tank.  What I will add is screen after gutter to remove debris, first flush device, catchment barrel, pump on a float switch in the barrel (all this x2 due to location of gutters), pumps will send water up a hill to a 2500 gallon holding tank through 30,10,1 micron standard 10" filters.  The big tank will gravity flow down into the existing 400gallon tank inside the house with a float valve, then after the house pump there will be 5 micron, 1 micron 20" filters and 10gpm uv sterilizer.  That estimate included i think around $2-2.5k labor and the rest materials, which tend to cost more here in Alaska.  Now I remember the tank was a lot less when I priced it recently (about $1/gallon of storage) so the estimate is more like $6k now.  Also that includes some demolition of an old wooden and plastic tank and logistics of getting things to our somewhat remote community.

 
John Schinnerer
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Really would need more context for a more on-target reply. Notice you are getting scattershot responses.

Some basic system design questions:
What's your annual precip, is it spread out thru year or wet/dry season (some details of typical precip pattern), what's your available roof footprint for catchment surface, what material(s) are used for the roofing, do you have elevation for gravity feed or all flat, are you on grid or off grid, if on grid do you want backup for water system if grid goes out (briefly, forever, something in between)? Just for starters...

Two quick hits:

1) If you drill a typical well, you only have water if you have electricity to run your pump, your pump doesn't break or can be fixed/replaced quickly & easily, and so on - the whole pyramid of industrial infrastructure. Or, you have a manual well pump and the physical energy to pump it enough to meet your essential needs. Or maybe the manual is a back-up. If you have an above-ground catchment tank and put a manual tap on it somewhere, you at least can get water out of the tank (and into the tank from rain) with no electricity needed.

2) Focusing on the word "potable" because that is the one piece specific enough to partly respond to...
Depending on what your catchment surfaces are, potable may not be an option or may require extra remediation (more $$ and or energy) to make it potable (see basic system design questions above).

If you want all water from all sources to be potable throughout a typical home, that is a different requirement than having the WHO minimum standard of ~20 liters (~5 gal) a day of potable water (and that is actually a lot, if you only need it for drinking and cooking).

So on the all potable everywhere end of the spectrum, you are looking at a sub-spectrum from whole-house 24/7 UV unit or reverse-osmosis unit (high tech industrial & electricity dependent) to a small slow-sand filter system (low tech partially industrial dependent, can be electricity-free if you have elevation to work with or non-electric means of pumping to elevation).

On the just enough potable for direct usage needs end of the spectrum, you are looking at a sub-spectrum from one-tap small UV systems (high tech industrial & electricity dependent) to a 2 or 3 or 5 gal. gravity-drip ceramic filter system (low tech partially industrial dependent, electricity-free, see "Potters for Peace" for lower tech than industrial-made ceramic filters).

NOTE that UV units must be on 24/7 OR you must never run water when they are off, because that will pull unsterilized water into the system. Unless you shut off the water main or turn off pump & depressurize pressure tank, depending on your source.

 
Matthew Rupert
Posts: 21
Location: Warsaw, MO
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John Schinnerer wrote:
2) Focusing on the word "potable" because that is the one piece specific enough to partly respond to...
Depending on what your catchment surfaces are, potable may not be an option or may require extra remediation (more $$ and or energy) to make it potable (see basic system design questions above).

If you want all water from all sources to be potable throughout a typical home, that is a different requirement than having the WHO minimum standard of ~20 liters (~5 gal) a day of potable water (and that is actually a lot, if you only need it for drinking and cooking).

So on the all potable everywhere end of the spectrum, you are looking at a sub-spectrum from whole-house 24/7 UV unit or reverse-osmosis unit (high tech industrial & electricity dependent) to a small slow-sand filter system (low tech partially industrial dependent, can be electricity-free if you have elevation to work with or non-electric means of pumping to elevation).

On the just enough potable for direct usage needs end of the spectrum, you are looking at a sub-spectrum from one-tap small UV systems (high tech industrial & electricity dependent) to a 2 or 3 or 5 gal. gravity-drip ceramic filter system (low tech partially industrial dependent, electricity-free, see "Potters for Peace" for lower tech than industrial-made ceramic filters).


Thanks for the thoughtful response John.  I am looking to purchase a piece of property to go off-grid with in the Ozark area of Missouri and am having trouble finding specific answers for a system that:

1. No electricity
2. All potable
3. Doesn't freeze in winter

I know I can bury the cisterns and that they make underground first-flush diverters.  I just do not know where I could put a .1 micron ceramic filter without worrying about it freezing.  From what I can tell, they don't make gravity-drip ceramic filters that can be put in-ground.  Does anyone know differently?  Could I make a small private insulation for the ceramic filter?  If I can solve that problem,  I think I can make a fairly simple gravity fed system that uses a hand-pump to get the water out of the in-ground cisterns.   
 
John Schinnerer
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Matthew Rupert wrote:
Thanks for the thoughtful response John.  I am looking to purchase a piece of property to go off-grid with in the Ozark area of Missouri and am having trouble finding specific answers for a system that:

1. No electricity
2. All potable
3. Doesn't freeze in winter

I know I can bury the cisterns and that they make underground first-flush diverters.  I just do not know where I could put a .1 micron ceramic filter without worrying about it freezing.  From what I can tell, they don't make gravity-drip ceramic filters that can be put in-ground.  Does anyone know differently?  Could I make a small private insulation for the ceramic filter?  If I can solve that problem,  I think I can make a fairly simple gravity fed system that uses a hand-pump to get the water out of the in-ground cisterns.   


Thanks for the extra info. A couple more thoughts & responses:

If you're talking about filtering all water from catchment sources to potable grade *before* it goes into your tank - that's not doable with a single tank and the highly variable input flow rates you'll have to that tank from a catchment source. The kind of filtration systems we can create with no electricity are slow and steady ("use small and slow solutions" ).
Even with electricity it's not realistic - UV systems and pressurized ceramic systems also have max flow rates that are relatively low compared to what you'd get from even a short cloudburst on your roof.

For simple no-electricity systems, filtering to make water potable is typically in small batches after you take the water out of the tank.
The ceramic filters I was thinking of are the counter-top gravity drip kind, for example:  http://doultonusa.com/HTML%20pages/portable_systems.htm
They'd be inside the dwelling, which I am assuming would be kept above freezing, at least when you're there and needing water...

For everything but direct potable uses (drinking, food prep, brushing teeth, etc.) what you'd get in your tank with reasonable best practices (gutter & downspout screens, closed system, no standing water in pipes, properly sized first flush diverter) would typically be fine for all other uses (bathing, dishwashing, etc.). Disclaimer - YMMV and testing would be a good idea. Essential reading from water guru Art Ludwig of Oasis design:
http://oasisdesign.net/water/quality/coliform.htm
http://oasisdesign.net/water/quality/testing.htm

A more infrastucture-intensive option that would get you a tank full of potable water would be to have two tanks, with filtration in between. The first tank could theoretically be smaller - it would be a 'surge' tank to handle big short-term inflows of water, and slow-filter into the second. You'd need enough elevation for this to gravity-feed, or, more technology to move the water.

A slow-sand filter would probably be your best option to try since you can size it to the rest of your system, and it's lower-tech and lower maintenance than the manufactured ceramic filter candles (plus none of the manufactured options really suit this application - whole house ceramic units need pressurized systems, and gravity drip models are too small and designed for stand-alone use only).
Essential reading (Art Ludwig again):
http://oasisdesign.net/water/treatment/slowsandfilter.htm

Re the freezing part:
Typically you don't need to bury the tank(s) completely. Get enough of the water below frostline and you might get ice on the top of the water, but the whole tank won't freeze. Basically you're putting the water in contact with below-frostline never-freezes earth temps - same as earth-sheltered dwellings. Which means berming up works the same way as earth-sheltered dwellings, to raise the frost line around the tanks - to reduce digging down, for reasons of both labor/cost, and, elevation for gravity feed systems.

If you did choose to go with two tanks and filtration in between, same applies to filtration. A slow-sand filter - basically, another small tank-type object - would only need to be dug down/bermed up enough to prevent freezing.
 
Jane Southall
Posts: 85
Location: Limestone, TN
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So I can use the filters in link to make rain water drinkable? Thank you.  Was just looking for something simple and inexpensive.
 
Peter VanDerWal
Posts: 83
Location: Southern Arizona
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solar power is so cheap these days that it's probably cheaper to go with a small solar power setup than all the effort and expense in making a system that is completely passive/gravity powered.
Then, depending on how much water you use, and how much room you have, you could put the filter, pump, etc. inside the house and not have to worry about freezing.

I used to be quite enamored with slow sand filters, but the more I read about them the less I want to use them.  When they work properly they do a good job, but at some point they need to be cleaned.  The cleaning process basically destroys the schmutzdecke and it needs to rebuild before the water is potable again.  Depending on the flow and other variables it can take a week or more before the water is potable again.  You'd need to either store enough clean water to get through that period, or have some other kind of filtering available. If you have other filtering then you don't really need the slow sand filter.
In order to produce safe water from a slow sand filter you need at least a 55 gallon drum, and it has to be kept warm or it stops working.  For a 55 gallon drum you need a flow rate of 5-7 gallons per hour, which means you'll also need to store at least a day's worth of filtered water (50 gallons or more depending on how much you use) which also needs to be kept warm.

If you go with more traditional filters, then the filters and pump could all fit under a kitchen sink.
 
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