50 Cubic Meter Underground Water Tank

[canopy]

I wish to make a tank to supply the water needs of a house fed exclusively by rainwater catchment. That means the tank must have enough water supply to last up to 6 consecutive months. I have read enough topics in the archives to understand an expert will be needed to properly design such a tank. How can I go about getting a sound design? I have no idea whom to contact or where to start.

Underground is not required, but it would be preferable to have the tank out of the way. Are there other tradeoffs to consider there? I plan to use a pressure tank to deliver the water since the house is near the highest elevation point. This is in mountainous terrain, high clay soil with good drainage.

[stevehaigh]

i would go with poured concrete floor and walls, 25cm floor, 20cm wall, 12mm steel on a 15cm grid

render about 2-3cm think to make it waterproof

the big advantage of a water tank vs. a pool is you can build internal beams to make it stronger if you feel its necessay

[canopy]

Can a mod move this to the DIY forum? Maybe a few more ideas can come from there.

Thanks Steve for that. Some good info there, but it also highlights the dilemma I am in since these specs are higher than locals have recommended, who by the way make leaky tanks and consider that to be normal. I would like a design from someone who has successfully done a project of this size before or better yet a design approved by a qualified engineer. But I don't know how to go about finding someone who could take this on.

[Crossy]

Moved to DIY, actually Farming may be better if we don't get any joy here.

Have you considered a half buried tank? You only have to dig half a hole and the spoil can be banked up against the above ground section for landscaping.

I've also seen large sectional circular tanks so they are available as an alternative (no idea where to get them mind) but are unlikely to be cheaper than concrete.

[sezze]

Does it have to be underground ? Otherwise you can use the designs i give you the link below . They are from UN in case of refugee camps where big watertanks are needed fast with limited supplies and money . The designs are tested by UN itself and are used . The plans /designs are constructed by Asian Institute of Technology in Bangkok . 3 designs are on the site complete from start to finish upto 90qm .

http://www.unhcr.org/49d089a62.html

[a99az]

I built a tank like this myself, in Spain, oddly it too was 50qm. I got a JCB in to dig a hole then made a concrete base, used solid blocks to build a five inch cavity wall. I supported the walls on the inside of the tank soil behind and pored concrete between the blocks. After that used beams and roof slabs for the top covered with 4 inches of concrete. Topped of with soil and you would never know it was there. Wish I had made it bigger now as we have had to pump water up from the well at times to keep us going on one or two dry years.

[Naam]

building that size of tank above ground is economical nonsense because the required additionally reinforced concrete walls are definitely more expensive than excavating (assuming easy access to use heavy equipment for digging and hauling away if the dug out soil can't be spread).

design the tank that you can cover it with available precast concrete slabs and get a pool builder. you might also consider to go for a bigger volume than 50m³ depending on the size of your family. an acquaintance of mine (civil engineer) has built 8 years ago an underground tank of 110m³ and uses ~85m³ p.a. (family of four); says until now he never used a drop of city water.

[sezze]

building that size of tank above ground is economical nonsense because the required additionally reinforced concrete walls are definitely more expensive than excavating (assuming easy access to use heavy equipment for digging and hauling away if the dug out soil can't be spread).

design the tank that you can cover it with available precast concrete slabs and get a pool builder. you might also consider to go for a bigger volume than 50m³ depending on the size of your family. an acquaintance of mine (civil engineer) has built 8 years ago an underground tank of 110m³ and uses ~85m³ p.a. (family of four); says until now he never used a drop of city water.

If you check the plans from the UN site i mentioned you'll see that not a big lot of materials is used . Above ground swimming pools are in general cheaper then underground swimming pools , due to easier materials .

When it is only for rainwater , underground with only a pond like construction lined with hdpe will be the cheapest . If you build a swimming pool like construction , then this will not come cheap .

[seedy]

.

http://www.unhcr.org/49d089a62.html

Thanks for the link.

\

I never considered ferrocement - but if they build sailboats from it, for sure it will work equally well to keep the water in.

Edited January 25, 2012 by seedy

[Khonwan]

Possibly useful further reading from 4 years ago: http://www.thaivisa.com/forum/topic/174236-water-tank/page__p__1870492#entry1870492

[Naam]

.

http://www.unhcr.org/49d089a62.html

Thanks for the link.

\

I never considered ferrocement - but if they build sailboats from it, for sure it will work equally well to keep the water in.

you think ferrocement is easily available in Thailand?

[Crossy]

you think ferrocement is easily available in Thailand?

I don't see anything in the UNHCR document BOQ that should not be readily available anywhere in Thailand.

[Naam]

you think ferrocement is easily available in Thailand?

I don't see anything in the UNHCR document BOQ that should not be readily available anywhere in Thailand.

just looked at the specifications and learned that steel-reinforced concrete is called "Ferro-Cement" by somebody who doesn't seem to know the difference between cement and concrete. that's for me the same pain in the butt when reading layman's terms "i live in a cement house" or "cement houses in Thailand don't last more than five years".

[Crossy]

just looked at the specifications and learned that steel-reinforced concrete is called "Ferro-Cement" by somebody who doesn't seem to know the difference between cement and concrete. that's for me the same pain in the butt when reading layman's terms "i live in a cement house" or "cement houses in Thailand don't last more than five years".

Much of the world has the same impression http://en.wikipedia....iki/Ferrocement looks like ferro cement does not use aggregate unlike concrete. That said, the Wiki seems confused about the usage of 'cement' and 'concrete'.

[Naam]

just looked at the specifications and learned that steel-reinforced concrete is called "Ferro-Cement" by somebody who doesn't seem to know the difference between cement and concrete. that's for me the same pain in the butt when reading layman's terms "i live in a cement house" or "cement houses in Thailand don't last more than five years".

Much of the world has the same impression http://en.wikipedia....iki/Ferrocement looks like ferro cement does not use aggregate unlike concrete. That said, the Wiki seems confused about the usage of 'cement' and 'concrete'.

no aggregate = crumble like a mole hill!

[tutsiwarrior]

I'd say find a local contractor that has built this type of underground concrete tank before with a submersible pump arrangement (or with a small forebay and a horizontal pump arrangement) then go and look at his work and ask the owner a few questions...on big seawater desalination projects in the Middle East they often have large underground concrete reservoirs for desalinated water storage...hooks right up to the water grid and the associated water demand...

Edited January 26, 2012 by tutsiwarrior

[Crossy]

no aggregate = crumble like a mole hill!

Hmmm, the stuff hold our bricks together does not contain aggregate, and it's bloody hard.

Lots of people have built boats using this material, and obviously UNHCR seem to think it works OK.

[Naam]

I'd say find a local contractor that has built this type of underground concrete tank before with a submersible pump arrangement (or with a small forebay and a horizontal pump arrangement) then go and look at his work and ask the owner a few questions...on big seawater desalination projects in the Middle East they often have large underground concrete reservoirs for desalinated water storage...hooks right up to the water grid and the associated water demand...

finding a contractor who has built an underground tank that size seems much more difficult than finding a pool builder who can do the job. no need for "ferro-seemant" just the bread-and-butter inground pool shell designed to take prefab concrete slabs as cover. as simple as that.

[Khonwan]

Jargon matters. Cement has no strength but the stuff between your bricks is mortar, i.e. cement and sand (and water, of course), which is strong. Sand is aggregate...fine aggregate.

[Crossy]

Jargon matters. Cement has no strength but the stuff between your bricks is mortar, i.e. cement and sand (and water, of course), which is strong. Sand is aggregate...fine aggregate.

Indeed, but in concrete we have cement, sand and aggregate (or is that really very coarse sand).

It doesn't really matter as our OP is really looking for an in ground tank and a pool-like construction with a simple slab roof as Naam suggests would do the trick. He should even be able to find someone to build it.

[Khonwan]

Like I said, jargon matters. Your "aggregate" is actually called coarse aggregate since sand is fine aggregate. Any builder, or handyman, capable of constructing a simple reinforced concrete slab is just as capable to build an underground tank.

[tutsiwarrior]

I'd say find a local contractor that has built this type of underground concrete tank before with a submersible pump arrangement (or with a small forebay and a horizontal pump arrangement) then go and look at his work and ask the owner a few questions...on big seawater desalination projects in the Middle East they often have large underground concrete reservoirs for desalinated water storage...hooks right up to the water grid and the associated water demand...

finding a contractor who has built an underground tank that size seems much more difficult than finding a pool builder who can do the job. no need for "ferro-seemant" just the bread-and-butter inground pool shell designed to take prefab concrete slabs as cover. as simple as that.

dunno...if we're talkin' about rainwater storage then we have a problem with corrosion and some sort of coating would be necessary...concrete coats easily...it ain't fer nothin' that country folks in Thailand use them big (impervious) ceramic pots to store their water...

Edited January 26, 2012 by tutsiwarrior

[Naam]

no aggregate = crumble like a mole hill!

Hmmm, the stuff hold our bricks together does not contain aggregate, and it's bloody hard.

Lots of people have built boats using this material, and obviously UNHCR seem to think it works OK.

that's not cement Crossy, it's mortar. aggregate is sand. and the UNHCR lists clearly fine and coarse aggregate.

Coarse Sand for Basement m3 14 21 25

Hollow Blocks pieces 150 280 195

Cement kg 3267 4553 5072

Fine Sand m3 4.26 6.0 7.0

Coarse Aggregate m3 5.0 7.0 8.14

Edited January 26, 2012 by Naam

[sezze]

Well , the UNHCR file tanks are build and tested in Thailand if you see the report and plans . They are complete from start to finish and even the sand grades are mentioned . It is 100% complete plans and work to be done .

Like i said , cheap underground , build pond like , with pvc or hdpe foil with concrete slabs on top for the cheapest . The plans from UNHCR are 2nd cheapest , a swimming pool construction is by far the most expensive .

[Crossy]

Coarse Sand for Basement m3 14 21 25

Hollow Blocks pieces 150 280 195

Cement kg 3267 4553 5072

Fine Sand m3 4.26 6.0 7.0

Coarse Aggregate m3 5.0 7.0 8.14

OK, Ok, you win, but I never said it was cement. However your own quote of the UNHCR document does NOT mention fine aggregate does it?

The building system is called Ferro Cement, even though it is incorrectly named as such (blame Joseph Monier for that), it's not really concrete either is it as it does not contain coarse aggregate, just sand and cement more like steel reinforced mortar.

[Naam]

Coarse Sand for Basement m3 14 21 25

Hollow Blocks pieces 150 280 195

Cement kg 3267 4553 5072

Fine Sand m3 4.26 6.0 7.0

Coarse Aggregate m3 5.0 7.0 8.14

OK, Ok, you win, but I never said it was cement. However your own quote of the UNHCR document does NOT mention fine aggregate does it?

The building system is called Ferro Cement, even though it is incorrectly named as such (blame Joseph Monier for that), it's not really concrete either is it as it does not contain coarse aggregate, just sand and cement more like steel reinforced mortar.

what part of the UNHCR material list (Bill of Quantities, page 17) which says

Coarse Aggregate m3 5.0 7.0 8.14

is open for the interpretation that it does not exist Crossy?

[Crossy]

At this point I think we have derailed the thread enough

[Naam]

i think it was important to "derail". the OP asked for advice and (i assume) for advice which is economical. if somebody asks me for advice what vehicle to buy for travelling from point A to point B i might recommend an affordable Honda Jazz or Nissan March instead of a UNHCR Rolls Royce or Bentley.

Edited January 27, 2012 by Naam

[Khun Jean]

Coarse Sand for Basement m3 14 21 25

Hollow Blocks pieces 150 280 195

Cement kg 3267 4553 5072

Fine Sand m3 4.26 6.0 7.0

Coarse Aggregate m3 5.0 7.0 8.14

OK, Ok, you win, but I never said it was cement. However your own quote of the UNHCR document does NOT mention fine aggregate does it?

The building system is called Ferro Cement, even though it is incorrectly named as such (blame Joseph Monier for that), it's not really concrete either is it as it does not contain coarse aggregate, just sand and cement more like steel reinforced mortar.

what part of the UNHCR material list (Bill of Quantities, page 17) which says

Coarse Aggregate m3 5.0 7.0 8.14

is open for the interpretation that it does not exist Crossy?

Well, the Coarse Aggregate together with the hollow blocks and Coarse sand is not for he ferrocement but for the basement and foundation.

This ferrocement structure is as cheap as you can get. It uses the least amount of material and is very strong. I would compare it with an old volkswagen.

I had some tests done with it (roofs) and it is very suitable for the ops purpose. I would not use it underground as the pressure difference can be to great resulting in failure.

http://www.ferrocement.net/ for more info.

Edited January 27, 2012 by Khun Jean

[Khun Jean]

Great examples and very good instructions:

http://www.pseau.org/outils/ouvrages/crs_the_banga_pinoy.pdf