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Best Underground Water Storage Options ?

 
Posts: 16
Location: Garden Valley, Idaho
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First post here so be gentle on the "use the search function" comments ;) .

Background -  I have a partially finished house in Idaho (zone 6a). Currently, it has NO WELL. Instead, it has a 3000gal above ground potable water storage tank (plastic) in a mechanical room located in the interior of the house. As the house was not setup with a rain catchment system when we bought it, we are temporarily paying for water to be delivered. Obviously, rain catchment is a no-brainer since part of the catchment system is already there (the tank, jet pump, etc). As a household we,  (mom, dad, 2 young children), use less than 25 gal of water per day on average, but life would be more comfortable at probably 35-40gal/day...

The Plan - After doing some research, we have been planning on burying one more storage tank on the north side of the house. I found the Norwesco HDPE tank, #44876 (5025 gal) for $6444 from a supplier in Utah - about a 6 hour drive from me, so I can just go pick it up to save most of the $1000+ shipping cost to have a big rig bring it up here. I was hoping to pour a slab, or do an earthen floor on top of the tank and build an addition over the top of it (this assumes the tank will never fail. Is that a bad assumption ? Do these tanks ever fail when properly installed ?

I'm planning to use the underground tank to do the "catching" and then pump it up to the in-house tank - hoping to settle out any solids that get past the first flush and TBD primary filter...

Is there a better option ? I've mostly ruled out a concrete cistern based on cost and the relatively cold zone we live in.  

Side question - Is there any benefit that can be gained from these two large thermal masses as I design my RMH and off-grid power system (currently the home has grid power and a standby propane generator) ?

Thanks for any input !

 
gardener
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This assumes the tank will never fail. Is that a bad assumption ? Do these tanks ever fail when properly installed ?



These tanks rarely fail (about the same frequency as HDPE septics), but all things in this world break down and need maintenance. Is this going to be a room underground that the tank sits in, or full on buried? If it's a room I wouldn't worry about it too much. You can patch it, or worst case rip it up with a sawzall and shove a bladder or different storage device in there. If it's full on buried, I wouldn't feel good about it unless you treated it like a temporary / disposable item. It will probably be fine, but in my experience it's always the things that are insanely difficult to get to that fail right when you need them most.

As a side-question, do you have any elevation change in your property? It seems like a bummer to have two tanks that both require pumps to operate.
 
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Location: catalonia spain
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Hi, I can't say anything about the HDPE tanks,  as I've not had any experience with them.

However concrete on the other hand I have, and can say that I built one under part of our house as a cistern and as a foundation/slab, almost 17 years ago now and am pleased to say it's held up fantastically well. It measures 7m x 3.5m x 1.40m. So, that's some 34,000ltrs.. Yes it was expensive to construct, but it was well worth the cost considering everything..

If you do decide to go concrete I'd be happy to go into details about how I built ours.

Good luck

Marcus
 
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Location: Brendansport, Sagitta IV
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What Kyle said. I don't like stuff I can't get at to maintain. Great way to ensure the part most difficult to get at is the one that fails!

And unless freezing is an issue with the existing tank, I wouldn't bury it at all. I'd put it above ground, on the highest point convenient to the house, and use its elevation as its own pressure system. (It's cheaper to pump occasional rainwater TO the tank than to run a pressure pump every day.) Build a barn around it and use the water mass as a heatsink, and the barn roof as your major catchment system -- a 1000 sqft barn could easily collect 500 gallons during a heavy rain.

What are you doing for filtering and purification? rainwater collected off any surface is going to contain a certain amount of poop from passing birds, and therefore coccidia (and increasingly, cryptosporidia which is much more pathogenic and difficult to treat).

 
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Hi Chris,
We are in N. Idaho-- zone 5, and are considering installing an underground back- up water holding system also.
I second Kyle's post-
I have not heard of any plastic tanks failing, but, I would be leary of building a permanent structure over the tank.
Would you elaborate on the earthen roof, please?

 
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chris florence wrote:First post here so be gentle on the "use the search function" comments ;) .

Side question - Is there any benefit that can be gained from these two large thermal masses as I design my RMH and off-grid power system



I've been thinking along the same lines myself, but a plastic tank might lose some of it's structural integrity if exposed to high temp water.  Considering the size of the tank you have, however, you might be able to raise the tank temp to 85 or 90 without significant problems.  It might even take more, but I wouldn't push it.
 
chris florence
Posts: 16
Location: Garden Valley, Idaho
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Kyle Neath wrote:



As a side-question, do you have any elevation change in your property? It seems like a bummer to have two tanks that both require pumps to operate.



We live on a steep slope so there's plenty of gravity to work with but digging a tank in above the grade of the house would be way more work than putting below grade. I'd have to build an access road to even get to a burial site. The tank in the house is already connected to a jet pump (1.5hp I think) to supply the house (with a pressure tank) but is plumbed in such a way that I can use the same pump to bring water in from an ouitside source to fill the tank as needed. Placing the tank below grade also simplifies the planned catchment system.

 
chris florence
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Rez Zircon wrote:What Kyle said. I don't like stuff I can't get at to maintain. Great way to ensure the part most difficult to get at is the one that fails!

And unless freezing is an issue with the existing tank, I wouldn't bury it at all. I'd put it above ground, on the highest point convenient to the house, and use its elevation as its own pressure system. (It's cheaper to pump occasional rainwater TO the tank than to run a pressure pump every day.) Build a barn around it and use the water mass as a heatsink, and the barn roof as your major catchment system -- a 1000 sqft barn could easily collect 500 gallons during a heavy rain.

What are you doing for filtering and purification? rainwater collected off any surface is going to contain a certain amount of poop from passing birds, and therefore coccidia (and increasingly, cryptosporidia which is much more pathogenic and difficult to treat).



Freezing is definitely an issue where we live. It's what adds a lot of anxiety to thinking about a catchment system that doesn't depend on 500 feet of heat tape . We've ruled out an above ground tank at this point. We have about 3000sqft existing roof and will add another 1000 when we have the $ for the addition. We can catch over 4 times our current water budget based on annual rainfall for this area - (45,000 gal annually on the existing 3000ft) so don't really need any more roof...

Filtering - I've been researching biosand filters but I think in our climate that is out . I'm definitely open to suggestions. I'm mainly worried about sand, ash, etc clogging things up over time or forcing me to climb into the tanks regularly to muck them out. Potability of the entire house supply is not critical - or at least that is my current thinking. Even with our current setup (having nonpotable water trucked in), we treat all water in the house as graywater, everything we drink or cook with goes through a Berkey filter. So definitely planning on a sand filter of some kind and maybe something additional for potability but it's not a high priority.

Thanks for your input though. Those are good ideas in the right climate.
 
chris florence
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Creighton Samuiels wrote:

chris florence wrote:First post here so be gentle on the "use the search function" comments ;) .

Side question - Is there any benefit that can be gained from these two large thermal masses as I design my RMH and off-grid power system



I've been thinking along the same lines myself, but a plastic tank might lose some of it's structural integrity if exposed to high temp water.  Considering the size of the tank you have, however, you might be able to raise the tank temp to 85 or 90 without significant problems.  It might even take more, but I wouldn't push it.



What I've found in research says that the HDPE tanks are good from 224f-248f, depending on the manufacturing process. In looking at most of the current wood gasification boiler stuff, the storage tanks are holding water in the 180f max range. That doesn't mean there might not be some deformation of the HDPE at lower temps - I need to contact the local rotomolding place that made my tank and ask them. Existing plumbing has PVC components that will need to be replaced if I go over 140f.

What it really comes down to, is how much wood I want to cut every year. Wood is the cheapest fuel here by far, but it's a lot of work ( then again, so is going to a job, to earn $, to pay for electric/propane/oil heat). I can get by with an efficient wood stove and no hydronics on about 4-5 cords a year or I might be able to cut that in half with a $12-15k boiler system. Hot water is so nice but I'm looking at it like a luxury at this point. If I could find a UL approved RMH design that would heat water I'd love to got that route but I'm not going to give up my homeowners coverage install it. Big bummer actually because I've been so excited about RMH's ever since I learned about them...
 
chris florence
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J. Jost wrote:Hi Chris,
We are in N. Idaho-- zone 5, and are considering installing an underground back- up water holding system also.
I second Kyle's post-
I have not heard of any plastic tanks failing, but, I would be leary of building a permanent structure over the tank.
Would you elaborate on the earthen roof, please?



We've since changed our plans and don't plan to build over the top of the storage tank. I mentioned an earthen floor, but not an earthen roof. Is that what you're referring to ? I like the idea of an earthen floor if I can pull it off but all the native soil around us is decomposed granite so I will have to truck in tons of clay if I go that route.
 
Creighton Samuels
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chris florence wrote:
Freezing is definitely an issue where we live. It's what adds a lot of anxiety to thinking about a catchment system that doesn't depend on 500 feet of heat tape . We've ruled out an above ground tank at this point. We have about 3000sqft existing roof and will add another 1000 when we have the $ for the addition. We can catch over 4 times our current water budget based on annual rainfall for this area - (45,000 gal annually on the existing 3000ft) so don't really need any more roof...



HAve you considered a rainwater pillow?  This wouldn't take heat much at all, but nor would it require freeze protection.

http://www.rainwaterpillow.com/

EDIT: It wouldn't require *much* freeze protection, as the pump might need it.  If you use underground pex as your connection piping, you don't have to worry about freeze damage, but you could still end up with a freeze blockage at an inconvenient time.
 
chris florence
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Creighton Samuiels wrote:

chris florence wrote:
Freezing is definitely an issue where we live. It's what adds a lot of anxiety to thinking about a catchment system that doesn't depend on 500 feet of heat tape . We've ruled out an above ground tank at this point. We have about 3000sqft existing roof and will add another 1000 when we have the $ for the addition. We can catch over 4 times our current water budget based on annual rainfall for this area - (45,000 gal annually on the existing 3000ft) so don't really need any more roof...



HAve you considered a rainwater pillow?  This wouldn't take heat much at all, but nor would it require freeze protection.

http://www.rainwaterpillow.com/

EDIT: It wouldn't require *much* freeze protection, as the pump might need it.  If you use underground pex as your connection piping, you don't have to worry about freeze damage, but you could still end up with a freeze blockage at an inconvenient time.



Thanks for the input Creighton ! That's a really interesting option ! I had not seen those before-  although I was really looking for an underground option. Are you saying that it wouldn't require much freeze protection because I mentioned the possibility of thermal storage ? I'm looking at wood boilers but with the cost vs. savings, it doesn't really pay off, other than it gets me off of an electric hot water heater - (which is definitely part of our plan) and I wouldn't have to cut as much cord wood.

I definitely wouldn't put one of those pillows outside, above ground in our zone but the option of putting it in the crawlspace sounds really appealing. It's about the same cost as an HDPE underground tank but there's no hole to dig. I have an extra tall crawlspace under the finished part of the house, which is also built with the ICF blocks. I'm assuming it probably never gets below freezing in there but I'll stick a hi-low thermometer down there and check it out this winter. If it will take any heat, that would be a great place to store it - kind of like a radiant heat bladder...

 
Creighton Samuels
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chris florence wrote: Are you saying that it wouldn't require much freeze protection because I mentioned the possibility of thermal storage ?



No, I'm saying that you don't need freeze protection on the pillow itself, because it won't take damage from freezing; mostly because it's not held under any pressure, and as it starts to freeze it will push excess water out it's over-spill, preventing a freeze break of the pillow.  It's also unlikely to freeze solid anywhere south of the Northern Territories, due to the heat that is emitted by water as it freezes, so the most likely event is that a portion of the water in the pillow freezes, but that also prevents the remainder of the pillow from freezing over.  The great risk of freeze damage is at the fittings and pump, which might need freeze protection if outside under a deck, but very unlikely in a crawlspace.

But if you could get one to freeze solid over winter, it'd make a great alternative to an 'icehouse'.



I definitely wouldn't put one of those pillows outside, above ground in our zone but the option of putting it in the crawlspace sounds really appealing. It's about the same cost as an HDPE underground tank but there's no hole to dig. I have an extra tall crawlspace under the finished part of the house, which is also built with the ICF blocks. I'm assuming it probably never gets below freezing in there but I'll stick a hi-low thermometer down there and check it out this winter. If it will take any heat, that would be a great place to store it - kind of like a radiant heat bladder...



That exact idea occurred to me as I wrote the last post, and I sent an email to them asking how hot the water can be inside the pillow.
 
chris florence
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They don't mention anything about cleaning the "pillow" in the maintenance routine. I'm curious how one would deal with both sediments and biological contamination. Seems that a rigid tank is going to be easier to clean if necessary...

The other (perceived) downside is that under some circumstance the thing might get punctured/ruptured and flood your crawlspace with a massive amount of water, but I guess that's true of pipes bursting, leaky fittings etc in conventional plumbing systems to some extent...
 
Creighton Samuels
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Creighton Samuiels wrote:

That exact idea occurred to me as I wrote the last post, and I sent an email to them asking how hot the water can be inside the pillow.



Safe high temp is 160 degrees F.

Minimum temp is 30 below zero.

Looks like it would work for both ideas.

http://www.rainwaterpillow.com/system-design/techincal-data-sheet
 
Creighton Samuels
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chris florence wrote:They don't mention anything about cleaning the "pillow" in the maintenance routine. I'm curious how one would deal with both sediments and biological contamination. Seems that a rigid tank is going to be easier to clean if necessary...


It's in the FAQ, I think.  Occasional addition of chlorine for biological contamination, and a flush as necessary for sediments.  But if you are using rainwater, there shouldn't be any sediment.  Also, if you are using it for potable water, they have an entire set of additional equipment for processing.

 
Rez Zircon
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Creighton Samuiels wrote:But if you are using rainwater, there shouldn't be any sediment.


Not true -- depending on conditions, rainwater can have enough sediment that it looks like ditchwater. Rain catches dust in the air; your roof catches dust and sheds a certain amount of grit; trees shed organic particles even if you don't see obvious leaves etc. This area isn't even dusty and I've had to scrape mud out of the gutters -- washed down the roof by the rain. Sand and coarser particles aren't the problem, as they'll settle out easily enough; what clogs filters is suspended microgrit.
 
Creighton Samuels
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Rez Zircon wrote:

Creighton Samuiels wrote:But if you are using rainwater, there shouldn't be any sediment.


Not true -- depending on conditions, rainwater can have enough sediment that it looks like ditchwater. Rain catches dust in the air; your roof catches dust and sheds a certain amount of grit; trees shed organic particles even if you don't see obvious leaves etc. This area isn't even dusty and I've had to scrape mud out of the gutters -- washed down the roof by the rain. Sand and coarser particles aren't the problem, as they'll settle out easily enough; what clogs filters is suspended microgrit.



Well, sure.  If your roof is asphalt it could be bad. If your roof is metal, it's less likely.  Also, that is what the first flush devices are for; diverting the first couple gallons that come off the roof during a rainstorm.  That's where the vast majority of the dust & clutter will be anyway.  And there is supposed to be a high flow filter to catch the particulates on the way in.  So, there shouldn't be any sediment, but it could still be dealt with if necessary.
 
chris florence
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Creighton Samuiels wrote:

Rez Zircon wrote:

Creighton Samuiels wrote:But if you are using rainwater, there shouldn't be any sediment.


Not true -- depending on conditions, rainwater can have enough sediment that it looks like ditchwater. Rain catches dust in the air; your roof catches dust and sheds a certain amount of grit; trees shed organic particles even if you don't see obvious leaves etc. This area isn't even dusty and I've had to scrape mud out of the gutters -- washed down the roof by the rain. Sand and coarser particles aren't the problem, as they'll settle out easily enough; what clogs filters is suspended microgrit.



Well, sure.  If your roof is asphalt it could be bad. If your roof is metal, it's less likely.  Also, that is what the first flush devices are for; diverting the first couple gallons that come off the roof during a rainstorm.  That's where the vast majority of the dust & clutter will be anyway.  And there is supposed to be a high flow filter to catch the particulates on the way in.  So, there shouldn't be any sediment, but it could still be dealt with if necessary.



Hopefully my filtration works perfectly, but I'm just trying to look down the road at any possible hassles - like not being able to clean fines out of a 10,000 gal bag. I do have a steel roof so that's a big help. Honestly, I don't think I'd even consider catching rain off of an asphalt shingle roof but I know that it's done. I'm planning on really tanking up on the snowfall we get up here, which has a fair amount of wood ash from our chimney. Pine pollen and all the airborne dirt (dust) that is around from dirt roads and driveway are major polluters. We usually have a forest fire in the summer thats close enough to drop a surprising amount of white ash on the roof....So, I expect the water that comes off the roof to be fairly loaded with superfine particles. Maybe there are certain things that will be in solution and then precipitate out in the pillow... ? I'm still looking at filtration but from what I gather, the cleaner you want the finished water, the more you're going to pay to get and maintain the filters. I like the idea of not having to replace expensive filter elements to maintain pristine quality in my tank/cistern/pillow...

Also, just for the sake of others who might read this thread, I looked at these Aquablox for awhile but decided I didn't have the right place to put a "modular pond"... Good option for some I'm sure. I thought about a budget version with milk crates too (legally purchased ones of course :)

AQUABLOCKS LINK

 
chris florence
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Also , I may not be using a First-flush diverter, at least not the traditional style, as they're tough to do in freezing climates. I came across this good thread about "cold weather catchment systems... some good stuff.

COLD CLIMATE CATCHMENT THREAD LINK
 
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Location: Blue Ridge Mountains, Western North Carolina, Zone 6b
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chris florence wrote:

Kyle Neath wrote:
As a side-question, do you have any elevation change in your property? It seems like a bummer to have two tanks that both require pumps to operate.



We live on a steep slope so there's plenty of gravity to work with but digging a tank in above the grade of the house would be way more work than putting below grade. I'd have to build an access road to even get to a burial site. The tank in the house is already connected to a jet pump (1.5hp I think) to supply the house (with a pressure tank) but is plumbed in such a way that I can use the same pump to bring water in from an outside source to fill the tank as needed. Placing the tank below grade also simplifies the planned catchment system.




I live in the mountains, and dead hemlocks frequently fall on the power lines here, taking out power for hours, sometimes days.  I debated for months if it was worth it to dig a 300' trench in the VERY rocky soil up to the highest point on my property to bury my new tank.  In the end, I decided to spend the time and money to do it, because I wanted to get as much water pressure as I could, so that I'd have running water with or without power.

I couldn't be happier about the decision.  I've lost power a good dozen times since then, and I have had water every time, due to the elevated tank.  It's not great pressure, and it's not hot (electric tank-less water heater), but I can wash dishes, flush toilets, get a glass of water to drink etc no matter the power situation.  Once I lost power while in the shower, and the pressure was enough to rinse off the soap, which was most welcome.  If I'd lost pressure while all soaped up, I would have been very unhappy.

When I was without power for nearly 4 days, it was just awesome to have running water.  Totally worth the effort, in my opinion.
 
pollinator
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re: heating water as thermal mass, using insulation to isolate the tank thermally, if you have sufficient water in the tanks most of the time, it seems like solar hot water might be a really good way to produce a bit of extra "free"heat. Especially if you can start storing the heat in the summertime.  You might even be able to use the water as air conditioning in summer gradually raising the temps of the water from a winter low to a summer high in the late fall when you're ready to start needing heat again.

One system I know of here actually has a problem in summer with excess heat boiling water out of the tanks and flooding the basement, but they are only 100 gallons or less

This works best if you have water that is not always cycling out for household use, but it does seem like when the rains align properly and the tank water is static it could help.
 
Posts: 184
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I have a few bits of info to offer, having done rainwater catchment systems for 5 different homes now.  
1:  it might be a good idea to shop around for the tank.  I recently purchased a 2500 gallon hdpe water tank (Norwesco) from Home Depot in Kenai Alaska for just over $1000.  
2:  an alternate means of collecting rainwater is to run the water from the gutter through a screen, first flush device, then into a 30-50 gallon barrel with a pump on a float switch that pumps it through filters into your tank, assuming you have electricity.  The first flush device can be in a conditioned space along with the catch and pump barrel (just be sure to put an overflow on the barrel as well as your big tank!). You can also put a diverter in your downspout to send all water away when everything is full (by manually turning a valve- easy if you switch from normal gutter to 2"dwv(drain/waste/vent) pipe (ABS). I usually pump sequentially through 30, 10, and 1 micron standard spun polyester filters 2" x10"-- filters should be available locally for under $7 each.  I usually have to change them 2-4 times per year, and the housings run around $30 each for culligan brand.
3.  starting for around $450 you can get a UV sterilizer.  If you put a 5 micron 4" x 20" filter after your pump then a UV sterilizer after that, you've got potable water throughout your house.  The UV sterilizer does need to operate continuously (i think its about 10 watts) and the bulb needs changed once a year (about $90).  Its recommended to do it this way rather than batch treatment before your tank because UV has no residual disinfecting power.
I did a write up on one system for a summer only cabin
https://permies.com/t/55399/potable-rainwater-harvesting-system-client
I hope some of this can be of benefit!  
 
pollinator
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chris florence wrote: I was hoping to pour a slab, or do an earthen floor on top of the tank and build an addition over the top of it (this assumes the tank will never fail. Is that a bad assumption ? Do these tanks ever fail when properly installed ?  


Besides assuming proper installation, the weight of the floor plus the weight of a cistern and especially the water all stacked like that is a pretty sure recipe for disaster. Once the lower tank is crushed, what would you be left with? Several systems would be my way to go, but I don't live where you are [We get 32"of water a year, pretty reliably.
What is your yearly rainfall? I would look a lot harder at rainwater catchment from the roof , even creating artificial "roofs" like tents/ tarps emptying in a cistern. http://www.rainbarrelguide.com/how-much-water-can-you-collect-in-rain-barrels-during-a-rainfall/
Other than that, I assume your water is beyond reach with a conventional/ affordable well? Wells are expensive, but the technology has been there for a long time, so once built, it is a pretty reliable thing too.
I wish you the best of luck. Let us know how you fare.
 
chris florence
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Corey Schmidt wrote:I have a few bits of info to offer, having done rainwater catchment systems for 5 different homes now.  
1:  it might be a good idea to shop around for the tank.  I recently purchased a 2500 gallon hdpe water tank (Norwesco) from Home Depot in Kenai Alaska for just over $1000.  
2:  an alternate means of collecting rainwater is to run the water from the gutter through a screen, first flush device, then into a 30-50 gallon barrel with a pump on a float switch that pumps it through filters into your tank, assuming you have electricity.  The first flush device can be in a conditioned space along with the catch and pump barrel (just be sure to put an overflow on the barrel as well as your big tank!). You can also put a diverter in your downspout to send all water away when everything is full (by manually turning a valve- easy if you switch from normal gutter to 2"dwv(drain/waste/vent) pipe (ABS). I usually pump sequentially through 30, 10, and 1 micron standard spun polyester filters 2" x10"-- filters should be available locally for under $7 each.  I usually have to change them 2-4 times per year, and the housings run around $30 each for culligan brand.
3.  starting for around $450 you can get a UV sterilizer.  If you put a 5 micron 4" x 20" filter after your pump then a UV sterilizer after that, you've got potable water throughout your house.  The UV sterilizer does need to operate continuously (i think its about 10 watts) and the bulb needs changed once a year (about $90).  Its recommended to do it this way rather than batch treatment before your tank because UV has no residual disinfecting power.
I did a write up on one system for a summer only cabin
https://permies.com/t/55399/potable-rainwater-harvesting-system-client
I hope some of this can be of benefit!  



Thanks for the input All ! After substantial research and carefully considering everyone's input, I've come up with a plan... I think !  . I believe strongly in redundant systems when it comes to our off-grid plan. I've come to realize that to do this safely and reliably (at least for our specific project), I'm going to have to incrementally phase out oil/grid dependency. For instance, the power line supplying electricity to our house can't be quickly replaced without spending more $ than we currently have at our disposal. Besides, our power bill is only $38-63/month  so, economically, it's not the highest priority. We solved the problem of "What if the power goes out?" , at least in the short term, by buying a standby, propane powered generator and will bury a 1000 gal propane tank next to the house in the spring. This buys us some time to reduce energy use in the house by replacing electric appliances as they fail - (which doesn't seem to take long these days) until we can afford solar options. By the time we're done, we'll have the option of solar, propane, or grid power depending on the circumstances...

So, keeping redundancy in mind,  I'm going to forgo any underground tanks and opt for the Rainwater "pillow" placed in the crawlspace (5000gal min, larger if we can afford it) - along with an above ground tank, or tanks,  upslope from us for the backup "pumpless" water pressure in case all power generation fails (and we can use it for irrigation without using the house pump). And I'll keep the existing above ground tank  (2750 gal) as the primary catchment tank in it's isolated mechanical room.  So, I see it working like this...

The HDPE tank in the mechanical room will be the first stop for "caught" water - after a sand filter placed in the same room. I'm thinking I can settle out whatever gets past the sand filter. I can setup the plumbing to pump off the top or the bottom of the poly tank with the turn of a couple valves. Sediments are easier to clean from this tank (compared to the pillow) as it has a manhole-sized lid to do a manual clean out periodically. So I can pump off the upper half of the tank if the water is going to be used in the house, or I can pump off the bottom of the tank and send it up the hill to the backup/irrigation tanks. I'm hoping that settling will lengthen the life of filter elements. Then, as Corey outlined, I'll filter water before it gets stored in the rainwater pillow, which will be our "water savings account".

I'd love to figure out ways to store heat in the water mass as well but it may create more hassle (and complexity) than it's worth. Solar thermal is a marginal-at-best option where we live. The sun only hits our house for about 4 hours on a cloudless winter day and cloudless winter days are rare.  We also have a lot of trees shading the house . PV solar, at least what I know of it, is a very expensive way to heat water, to in turn heat your house. Firewood is cheap, clean(er) and uncomplicated. Wood heat stored in water is the most efficient energy conversion model possible here but the initial costs are so high we've pretty well given up on solar, boilers and radiant systems for heating needs...
 
Corey Schmidt
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Thanks for the update!  I'm curious about the sand filter you mentioned.   Does it work on gravity flow?  if so what kind of flow rate can it accommodate with how much head pressure?... I'm slowly building my own house between jobs and as it will be off grid I'm looking to limit electricity usage as much as possible.
 
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Here in Australia I use elevated tanks as my water source.
With no pumps, the tanks fill from shed roofs. My Hot water tank, with a thermo syphon solar panel system sits about 6 feet [1.8M] above the taps where it is used. I use 25mm or 1 Inch pipes to the taps and I have adequate water pressure for the domestic situations. The shower runs fine also.
When laying the pipes its important not to create an air pocket, because water will not flow through it. If I accidentally create an air pocket, I put a valve [tap ] at that location so the air can be let out. Sometimes an air valve can be used, but you may get a small discharge of water without realising it.
 
Corey Schmidt
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John C Daley wrote:Here in Australia I use elevated tanks as my water source.
With no pumps, the tanks fill from shed roofs. My Hot water tank, with a thermo syphon solar panel system sits about 6 feet [1.8M] above the taps where it is used. I use 25mm or 1 Inch pipes to the taps and I have adequate water pressure for the domestic situations. The shower runs fine also.
When laying the pipes its important not to create an air pocket, because water will not flow through it. If I accidentally create an air pocket, I put a valve [tap ] at that location so the air can be let out. Sometimes an air valve can be used, but you may get a small discharge of water without realising it.



Do you have any filtration or purification system?  What do you do for drinking water?  Its good info for me that 6 feet is enough pressure for your needs, thanks!
 
John C Daley
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I don't filter or purify the water, its ok for drinking  as it comes from the tanks.
I am surprised when I read of the things you do to water before using it.
Is it necessary?
 
Creighton Samuels
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John C Daley wrote:I don't filter or purify the water, its ok for drinking  as it comes from the tanks.
I am surprised when I read of the things you do to water before using it.
Is it necessary?



Probably not, depending upon what your roof catchment surface is made of, and how it's stored.  But keep in mind that Americans tend to be more germaphobic than most of the world, and building codes include these phobias in spades.  So even if less or no filtering would be acceptable to the local building code enforcement dicks, it might not be acceptable to the homeowners, or the next homeowners.  
 
Corey Schmidt
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John C Daley wrote:I don't filter or purify the water, its ok for drinking  as it comes from the tanks.
I am surprised when I read of the things you do to water before using it.
Is it necessary?


Strictly speaking, its not necessary.  but....Freezing weather half the year and small lot sizes complicate design of strictly gravity flow systems, and almost everyone has grid electricity, which makes adding a pump or two an easy solution.  We have high loads of bird poop, pollen, and leaves on the roofs, and we get mostly drizzle and mist rather than downpours, so first flush devices don't accomplish a lot.  There are also a lot of cultural fears and reservations about using roof caught water here.  But even people with grave fears about bird poop are reassured by the efficacy of a UV sterilizer.  And people don't want sediment building up in their tanks.  
  For years I drank untreated creek water without incident, and quite enjoyed the slightly yellow color, thinking of it as herbal medicine. It came from a dammed creek by gravity in the summer and in winter I would kayak to the creek (there is a narrow channel of seawater between that creek and the island I live on) and fill up a bunch of plastic bottles and haul them home in my 'low rider' kayak.  But my mother came to visit about 6 or 7 years ago and left with giardia.  That was from surface water and not roof water.  I sometimes look into my own outdoor tanks and see the crystal clear water and wonder if my 'minimal' 2 filters in my home system are necessary.  I tested for coliform bacteria recently from the outdoor tank and it was positive.  Then i tested from my drinking tap, which comes from a .5micron carbon block filter, and it was also positive....
 
Rez Zircon
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When you're exposed to pathogens, first you get sick (eg, giardia or E.coli can be mistaken for stomach flu, or may manifest as just a bout of diarrhea), then you develop immunity. So just because you don't get sick on untreated water doesn't mean it's pathogen-free, or safe for someone who hasn't had prior exposure, or who might be immune-compromised (like an infant or an elderly person). Drink untreated water from a different source, with different pathogens, and you might get a rude surprise.

This is fundamentally the reason why tourists come down with Montezuma's Revenge. It's also one of the major causes of 3rd-world infant mortality, and historically was the leading cause of death in armies on the march.

There was an interesting study about 30 years ago on pinworms in children. They found that even tho none of the kids tested had active infections, about 30% had antibodies indicating a prior pinworm infection. (Yes, your immune system also reacts to ascarids, eg. pinworms and roundworms.) This isn't necessarily a totally bad thing -- another study found (and this parallels my own experience) that puppies actually benefit from early roundworm infection, because it kickstarts their immune systems (which then evict the roundworms when the puppy is about a year old), and this relationship is critical enough to regard roundworms as a symbiote rather than a parasite. But while some exposure might be good, an overload can stunt or even kill the host. (Ascarids, giardia, and coccidia tend to overgrow when the diet is high in fiber or mucus-producing stuff like soy, because that protects them from being attacked by the host's antibodies. Another reason to eat plenty of meat and not so much plant material.)

 
John C Daley
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Cisterns, underground water reservoirs have been used in the old world for centuries.
Rome, middleEast etc.
Do the research
 
gardener
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So Chris, did you implement your water storage plan?

I'm pondering water storage in zone 6, where I'm wondering if the use of insulation like a PAHS umbrella would prevent freezing if the tank was buried under that umbrella of insulation. The idea would be to pump the tank full in the fall while there's still plenty of sun, then not need to run the well pump in the winter when there's very little solar charging available (off grid, would prefer to not use/rely on a generator).

I don't have warm fuzzies though about having such a large water source near the house, plus having enough pressure with gravity alone would work better in an elevated structure a little bit away from the house. So building a small shed to house the storage tank sitting on an elevated foundation, and the well itself, is probably the better option. I could then build my first/test RMH in that space, and make sure it is well insulated, so winter temps don't risk any freezing, and the RMH would be there as insurance in case it got really cold for an extended period.

I could then trench a line from that shed into the house and have it go through various mesh size filters, and for cooking/drinking I would continue to use my Berkey filter as well. I've found that even a foot of head is enough for sink use, but for a hot/warm shower warming water up and getting it high enough for my 6'6" tall head to stand under is a different challenge.
 
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John C Daley wrote:Here in Australia I use elevated tanks as my water source.... I use 25mm or 1 Inch pipes to the taps and I have adequate water pressure for the domestic situations. The shower runs fine also.
....



Could you post a picture of your shower heads?  They are gravity fed?
 
Orin Raichart
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Marcus vandell wrote: a cistern and as a foundation/slab, almost 17 years ago now and am pleased to say it's held up fantastically well. It measures 7m x 3.5m x 1.40m. So, that's some 34,000ltrs..

If you do decide to go concrete I'd be happy to go into details about how I built ours.



Hi Marcus, how thick were your walls for your cistern? what spacing did you use for the rebar?  did you seal the concrete?     ....I may build one in the ground using stone rather than concrete but I am curious about yours for an idea of structural strength.
 
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