Storage Tank Idea

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gorsuchmill

Member
Mar 14, 2008
105
Central MD
I'm thinking of constructing a non-pressurized tank that I can fit into a 5' high crawlspace. In order to get it through a narrow door (approx. 24" wide) I'll need to do some of the construction in the space. The tank will be round, approx. 7.5' in diameter, and will use an EPDM liner. My plan is as follows:

1) cut a 7.5' diameter circle in some OSB (2 4x8 sheets) that is overlapped and screwed where the two halves meet. I'll probably lift the circle off of the floor with some 2x4 blocks so that the circle will be slightly above the bottom of the tank. This circle will provide bottom support for the walls.

2) make a circle out of 4x8 sheets of 1/4" luaun laying on their side. This will make the walls 4' high and will require three sheets to complete the circle. Layer a second circle within the first, gluing the sheets to the outer sheets, staggering the seams. This process will be repeated with a third inner circle, which will provide 3/4 of wall thickness. The reason for the luaun is its flexibility for forming the circle. Once formed, I would likely run bolts through all three layers to make sure the "laminated" circle doesn't peel apart.

3) to get the tank into the crawl space I would remove the bottom support, which can be screwed back together in its final location. I would cut the tank vertically in one place, and hope to be able to maneuver the 24' long wall into place, where the circle can be re-formed and bolted back together with some type of mending plate. If a single tank cut doesn't work, I may have to cut the tank into 2 halves and attach them accordingly.

4) line the floor of the circle with 4" of foam board, and 2" of foam on the walls. Line the walls again with a layer of bubble wrap insulation.

5) place the liner within the tank and fill.

6) for additional wall support I'm considering 2, 1/4" cables to surround the tank and connected in a circle with a turnbuckle. This will allow for tightening.

7) additional vertical support may be gained by attaching angle iron vertically every 3' or so, and feeding the cable through it.

8) a lid will be made out of similar material; however, protected from moisture with additional epdm or mil plastic.

Any obvious pitfalls to this design? I like the STSS tanks, but think I can construct the above in an afternoon at a cost of $400 or so, not including the liner.

Thanks.

- Lee
 
Interesting idea. If you need to use cables you might want to consider vertical strips of wood between the luan and cables, spaced every so often around the perimeter to spread the load and prevent localized forces from the cable onto the luan.

Also, what type of foam would you be using to line the walls? I think foam board would be too rigid to make the curve.
 
I am currently building my tank.I used 20 gauge galvanized sheet metal.I riveted the seams and will use an edpm liner.I think the luan will be difficult to work with
 
Good suggestion on the wood supports. I was thinking of using angle iron, but wood would be easier to deal with and could be screwed to the tank walls from the inside. So as not to initially deform the tank, the cables wouldn't be tightened until after I began to fill it with water.

Regarding the interior insulation, I was going to rip foam board into strips of 6" or so on the table saw. Then I would tack them into place with a small dollop of adhesive. Once the liner was filled, the foam wouldn't be going anywhere. I realize this would make the interior modestly out of round, but that shouldn't matter to the epdm. And though it would also leave some small air gaps where the back sides of the insulation strips would otherwise meet, it seems to me that would be just as insulative anyway.
 
Wooden water tanks have been around for a long time. Not too
many around in recent years, but I have seen a fairly new one
made out of redwood. Constructed like a wood barrel. Vertical
staves on a t&g;base. It's a water tank on a ranch, doesn't leak
maybe 5000 gallons. Steel bands around the outside. Sits on
a flat rock base. MM
 
Jim -

It seems most of the non-pressurized tanks discussed here use epdm liners, as does STSS. Max temp appears to be 175* without compromising long-term durability.
 
Jim -

Looks like an interesting product. You'd have to confirm it can handle underwater temps as high as 180* for extended periods of time, but, if so, could be an alternative to epdm. As for your baseboard rads, most continue to deliver heat at water temps well below 180*. I'm told cast iron radiators are good down to 130-140*.

Lee
 
The volume of the storage tank can be determined by the following factors:

* Number of persons in the household: The greater the number of persons, the greater the storage capacity required to achieve the same efficiency of fewer people under the same roof area.
* Per capita water requirement: This varies from household to household based on habits and also from season to season. Consumption rate has an impact on the storage systems design as well as the duration to which stored rainwater can last.
* Average annual rainfall
* Period of water scarcity: Apart from the total rainfall, the pattern of rainfall -whether evenly distributed through the year or concentrated in certain periods will determine the storage requirement. The more distributed the pattern, the lesser the size.
* Type and size of the catchment:Type of roofing material determines the selection of the runoff coefficient for designs.
_______
jackspar.
WideCircles
 
I used a Firestone EPDM because the temp rating was higher. I don't have that off the top of my head but looking at Firestone's webiste would find it.
 
Regarding the interior insulation, I was going to rip foam board into strips of 6” or so on the table saw.

Try the same approach as your outer wall. 1/2" foam board bends slightly. I would use the blue board on outer layers and finish with polyiso for inner most layer due to higher temp resistance.

Remember to use foam board compatible glue on the unfaced stuff. How about cutting strips of galvanized for the bands with the ends bent and bolts used for clamping action. 18 ga. would work. Not sure how a turnbuckle due to its length would work. Also most turnbuckle's are China made I would make
sure I got some high quality ones if going that route. Prolly flatten out that section. I would use advantek instead of osb. Much stronger and is water resistant. Are you gonna bury the tank any for additional wall support ?
Will
 
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