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JDCanuck
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Hi Pacificobob: Roofs alone get 7620 liters each inch of rain, courtyard and driveway another 7620 liters for each inch of rain. Total rainfall of 4
inches about 61,000 liters per year. I think La Paz has significantly more rainfall than 10 cm per year. Only 2/3 would be recoverable, the rest lost
to evaporation on lighter rainfalls. This is what results in 40,000 storeable after filtration.
Recommended cisterna installations have a large cement cap placed over them, something I want to avoid and instead looking for a fully buried type of
storage container that I can cover with lightweight material or artificial grass. Cement maybe?
[Edited on 3-17-2022 by JDCanuck]
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Bob and Susan
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i don't know what "baja" you guys live in but there isn't enough rain here to justify the cost of building a "water catchment"
we live in a desert...maybe....6 days of "real rain" a year
and most of that water would be "muddy"
it looks like some of these numbers are "made up"
[Edited on 3-17-2022 by Bob and Susan]
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JDCanuck
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Quote: Originally posted by Bob and Susan  | i don't know what "baja" you guys live in but there isn't enough rain here to justify the cost of building a "water catchment"
we live in a desert...maybe....6 days of "real rain" a year
and most of that water would be "muddy"
it looks like some of these numbers are "made up"
[Edited on 3-17-2022 by Bob and Susan] |
Yes, I agree, very little rainfall, most of that in Aug and Sept on very few days and the trick to capturing is filtering out the silt before storing.
Here is the climate data for La Paz:
http://www.baja-california.climatemps.com/precipitation.php
According to that table in La Paz in the months of Aug and Sept you would get (on average) 80,400 liters of water falling on 600 sq meters. Far less
in other months and would not be useable. Our plan is to capture and store for reuse 40% of that each late summer and mix with well supplied water.
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pacificobob
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I have 15 underground 10k liter tanks. The water that fills them once a week is ejido irrigation water. It often contains sediment. This quickly
settles and I usually clean it out once every 2-3 years. Actually, I hire a kid who can fit into the tanks to do so.
The tanks are in concrete block vaults with concrete lids. A bodega is over several tanks...a vivero over the others.
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JDCanuck
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| Quote: Originally posted by pacificobob | I have 15 underground 10k liter tanks. The water that fills them once a week is ejido irrigation water. It often contains sediment. This quickly
settles and I usually clean it out once every 2-3 years. Actually, I hire a kid who can fit into the tanks to do so.
The tanks are in concrete block vaults with concrete lids. A bodega is over several tanks...a vivero over the others.
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Pacificobob: Thanks for that info. If I was to use 3 - 15K liter tanks my plan was to feed semi-filtered water to the two outside tanks and pump from
the inner tank linked with a high level tie in. I had planned if i went this route to be cleaning the accumulated silt from the outer tanks about
every two years. Sounds like your experience supports that idea. If I use instead one very large buried cement or fiberglas tank I would need far
frequent cleaning or far better pre filtration.
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pacificobob
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I have avoided concrete tanks for fear of leaks. I have a neighbor who has one that works just fine. No different than a swimming pool with a
concrete roof.
I imagine the cost is similar.
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Bob and Susan
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the plastic tanks WILL crack one day...
its not if its when
a concrete vault with a cement lid is a BAD idea...how do you replace a bad tank?
if water fills the vault you have to use a sump pump to empty it or MOLD arrives....
if vault is full of water the tanks could "float" if not kept FULL
bad idea
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gnukid
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| Quote: Originally posted by Bob and Susan | the plastic tanks WILL crack one day...
its not if its when
a concrete vault with a cement lid is a BAD idea...how do you replace a bad tank?
if water fills the vault you have to use a sump pump to empty it or MOLD arrives....
if vault is full of water the tanks could "float" if not kept FULL
bad idea
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We need water to live in a desert, we use all methods available, spring water, pila, city water etc, underground tanks are often required to allow low
pressure water to arrive below ground level, the cement cistern can be used on its own as a cement pool, or with plastic tanks inside, if the plastic
overflows, an inexpensive sump pump can be used to refill overflow to tanks, if they crack they can removed by entering the cement cistern and cutting
apart the plastic, and reinforce the cement tank for use. Mine have never cracked in twenty years, though, its seems cement cistern without plastic is
most reliable and most efficient use of space and resources.
All options work, multiple separate methods work great. Underground cement with plastic inside has low wear due to reduced sun shine, I have used
these for twenty years with no failure, if they fail, I remove them, If I want I replace them.
Plastic tanks inside cement, below ground is the most secure option and is recommend over plastic only or cement only for clean water, with reduced
risk of contamination, and better temperature control.
I use high pressure submersible pumps below grade along with grade level pressurize regulated tanks, since they are quiet, powerful and reliable.
There is a simplified cheaper method when water pressure exists to fill above ground tanks. Put an above ground tank n cement pad in shade, put
submersible pump inside, and pressure regulated switch outside. When you open the spigot the pump turns on, spigot closed the pump turns off.
[Edited on 3-18-2022 by gnukid]
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JDCanuck
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| Quote: Originally posted by Bob and Susan | the plastic tanks WILL crack one day...
its not if its when
a concrete vault with a cement lid is a BAD idea...how do you replace a bad tank?
if water fills the vault you have to use a sump pump to empty it or MOLD arrives....
if vault is full of water the tanks could "float" if not kept FULL
bad idea
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I take it you have no cistern installed at your place? Are you on piped in water, or do you have it delivered by truck to a roof top tank? Neither of
those are available at our place so we already have a buried 10K liter tank which presently holds water for the house for about 2 to 3 weeks use if
the supply system goes down, which it did this past year following the storm and the tank did go empty. We did have a cement cistern back on the farm
generations back that lasted quite a few decades and this would be my preference if it's available.
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mtgoat666
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There are lots of good plastic tanks designed for underground use, poly, fiberglass, etc., you just need to find a local vendor. Most new septic
tanks here in usa are plastic type, they work fine for decades (plastic probably lasts longer than concrete for septic, concrete gets eaten by acid
gasses)
Tank floatation is not a problem unless you have high water table. And tank floatation in high water area can be mitigated by using deadmen anchors.
Reinforced concrete, precast or cast in place, makes for good tank. Not a fan of the block and mortar tanks used in Mexico….
Get a competent contractor that builds tanks right!
Woke!
“...ask not what your country can do for you – ask what you can do for your country.” “My fellow citizens of the world: ask not what America
will do for you, but what together we can do for the freedom of man.”
Prefered gender pronoun: the royal we
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JDCanuck
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| Quote: Originally posted by pacificobob | I have avoided concrete tanks for fear of leaks. I have a neighbor who has one that works just fine. No different than a swimming pool with a
concrete roof.
I imagine the cost is similar. |
Hi Pacificobob: That was my fear too, and I have been unable to find any local sources for the precast strengthened cement storage units available in
the US. Problem also with that would be getting them delivered and installed to my remote location. Your solution seems to be the most often
recommended one. I'd be interested in the cost and any issues you have run into if you wouldn't mind sharing that?
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Bob and Susan
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yes i too made this mistake...I have... even now... plastic tanks in a cement bunker below the ground...each tank has a shut off valve to isolate it
I originally thought the water would stay cooler...no way
the tanks cracked one at a time
The cement floor fell apart
I had to cut a BIG hole in the cement top to remove the tanks
I replaced all the tanks...replaced the floor...added a sump pump for seepage and ground vent for tide water
Even the best plastic water tanks break..,don't be fooled
Cement septic tanks are illegal...only plastic and fiberglass are acceptable....permits are required
No one should do this...tanks are better above the ground and accessible for service
dont listen to these guys...they are WRONG
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JDCanuck
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Bob: Yes that a huge number of issues you ran into! Thanks for sharing and I will have to add them to my cautionary planning.
Did you install these tanks below an existing or fluctuating water table which pushed the floor up causing the tanks to flex?
Unfortunately, as much as I'd like to install above ground tanks for simplicity, it wouldn't be applicable as the existing and future tanks are
gravity fed from a lower level than yours seem to be. I am definitely stuck with some kind of buried tank. I am 25 meters above sea level so tides
won't affect me as they seem to have you.
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mtgoat666
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A properly built UG tank will last several decades or more.
Susan, your situation of flat lot next to ocean with shallow GW is a difficult site for UG tanks. In your particular case you are probably better off
with surface tanks.
Woke!
“...ask not what your country can do for you – ask what you can do for your country.” “My fellow citizens of the world: ask not what America
will do for you, but what together we can do for the freedom of man.”
Prefered gender pronoun: the royal we
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pacificobob
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| Quote: Originally posted by Bob and Susan | yes i too made this mistake...I have... even now... plastic tanks in a cement bunker below the ground...each tank has a shut off valve to isolate it
I originally thought the water would stay cooler...no way
the tanks cracked one at a time
The cement floor fell apart
I had to cut a BIG hole in the cement top to remove the tanks
I replaced all the tanks...replaced the floor...added a sump pump for seepage and ground vent for tide water
Even the best plastic water tanks break..,don't be fooled
Cement septic tanks are illegal...only plastic and fiberglass are acceptable....permits are required
No one should do this...tanks are better above the ground and accessible for service
dont listen to these guys...they are WRONG
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As much as you enjoy urinating on other's cornflakes...I must disagree.
Mine have been in service for 17 years without any issues. It sounds like you employed poor materials and workmanship.
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JDCanuck
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| Quote: Originally posted by mtgoat666 | There are lots of good plastic tanks designed for underground use, poly, fiberglass, etc., you just need to find a local vendor. Most new septic
tanks here in usa are plastic type, they work fine for decades (plastic probably lasts longer than concrete for septic, concrete gets eaten by acid
gasses)
Tank floatation is not a problem unless you have high water table. And tank floatation in high water area can be mitigated by using deadmen anchors.
Reinforced concrete, precast or cast in place, makes for good tank. Not a fan of the block and mortar tanks used in Mexico….
Get a competent contractor that builds tanks right!
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All excellent comments ! Thanks for the input. I am definitely leaning back to buried Rotoplas again as the local contractors install a lot of them
fairly cheaply and the comment about cement blocks is inline with my thinking. Structural strength to resist cracking would be a big concern with
cement blocks. They would also tend to leach out calcium that I am trying to reduce in the water supply.
The strengthened ribbed buried fiberglas or poly that don't require cement surrounds of that size get very expensive and I'm not sure they would even
be available in that area.
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mtgoat666
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Location: San Diego
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| Quote: Originally posted by JDCanuck | | Quote: Originally posted by mtgoat666 | There are lots of good plastic tanks designed for underground use, poly, fiberglass, etc., you just need to find a local vendor. Most new septic
tanks here in usa are plastic type, they work fine for decades (plastic probably lasts longer than concrete for septic, concrete gets eaten by acid
gasses)
Tank floatation is not a problem unless you have high water table. And tank floatation in high water area can be mitigated by using deadmen anchors.
Reinforced concrete, precast or cast in place, makes for good tank. Not a fan of the block and mortar tanks used in Mexico….
Get a competent contractor that builds tanks right!
|
All excellent comments ! Thanks for the input. I am definitely leaning back to buried Rotoplas again as the local contractors install a lot of them
fairly cheaply and the comment about cement blocks is inline with my thinking. Structural strength to resist cracking would be a big concern with
cement blocks. They would also tend to leach out calcium that I am trying to reduce in the water supply.
The strengthened ribbed buried fiberglas or poly that don't require cement surrounds of that size get very expensive and I'm not sure they would even
be available in that area. |
Don’t bury a tank that is not designed for burial!
Just because a tank is not stocked locally, does not mean it cannot be ordered.
I really doubt vendors keep UG tanks in stock. Just order a proper tank, and hire a competent/experienced contractor to install it.
Woke!
“...ask not what your country can do for you – ask what you can do for your country.” “My fellow citizens of the world: ask not what America
will do for you, but what together we can do for the freedom of man.”
Prefered gender pronoun: the royal we
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TSThornton
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I live rural in the US on a low-yield well. I have a direct buried plastic tank adjacent to a pressure pump and tank subgrade in concrete rings. The
rings had to be drained well with a pipe running down grade to daylight to allow sub-grade flow to move through them, but otherwise they've worked
great for 22 years and counting.
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JDCanuck
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| Quote: Originally posted by TSThornton | | I live rural in the US on a low-yield well. I have a direct buried plastic tank adjacent to a pressure pump and tank subgrade in concrete rings. The
rings had to be drained well with a pipe running down grade to daylight to allow sub-grade flow to move through them, but otherwise they've worked
great for 22 years and counting. |
Sounds like a great well thought out design. Every location seems to have it's own issues and yours sounds both simple and inexpensive taking
advantage of the slope available for drainage. How does your tank get supplied? Captured rainwater, or as a reservoir to hold well water for surge
demands?
I have to admit, I find using concrete chamber rings a great idea to keep it both durable and simple. I had never thought of that. They come in very
large sizes where you are located I guess?
[Edited on 3-18-2022 by JDCanuck]
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TSThornton
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Yes, the rings are about 3 feet or maybe a little more in diameter, large enough to get down into to service the equipment. The cistern is filled by
the well, but the well is about a 1/4 mile away and we wanted the storage to insulate against well failures (equipment or yield), and we've been glad
to have it a few times over the years.
[Edited on 3-18-2022 by TSThornton]
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