What type of water tank storage tank?

   / What type of water tank storage tank? #1  

stumpfield

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Dec 7, 2005
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436
Location
Sierra Foothills
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2005 MT265B
I need get to get a 5000gal storage tank for a gravity feed water system. What type of tank should I get? Plastic or steel or ???? For plastic tanks, I can get 2 2500gal tanks cheaper than 1 5000gal tank. I wonder why? It probably takes more material and labor to make 2 2500gal tanks than 1 5000gal tank but it's a few hundred $ cheaper for 2 tanks from the same manufacturer. Any potential problem or maintanence issues for having 2 smaller tanks instead of one big tank? I appreciate your comments. Thanks.

Also, how should I prepare the base for the tank? Just dirt? gravel or a concrete pad? I was thinking of pouring a concrete pad but my well guy recommend against it. He said unless I have it engineered to support the weight, I would be better off with just dirt or gravel. What do you think?
 
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   / What type of water tank storage tank? #2  
That's only 41,750 lbs plus the weight of the tanks. I would use concrete with a trench crossing in the middle and borders.
 
   / What type of water tank storage tank? #3  
I have mine setting on a mound/base of sand that I get for free by just hauling it out of the sand wash. i have two different size tanks setting side by side and just use the amount of dirt/sand to adjust them to the same height they been there for three years with no problem. You only need to feed water into one tank and then have them connected together at the bottom and they will self level. I think it would be easier to work with two 2500 tanks than one big 5000 one.
 
   / What type of water tank storage tank? #4  
Just got 6 Black Polyethylene 2500 gal tanks. Setting each on a clay pad - happens to be my local free mat'l. I was worried about how flat the pad had to be, but after seeing how thick the bottoms are, I have no worries about that. I layed the clay in 4" lifts, compacted with the tractor tires, backed over the pad with a single blade and finished off any obvious holes and bumps with a rake.

2500 gal tanks are 300+ pounds so they can be pushed around by hand, etc. Setting the bottoms level with the bottom of my barn siding (they are distributed around the barn under downspouts) so that they are all about the same level. They will be tied together via the bottom drain through a common manifold to allow them to equalize and then tied into our existing rainwater/creek water distribution system.
 
   / What type of water tank storage tank? #5  
I have been told that you would fill the tank and allow it to settle for a few weeks prior to making permanent connections. With two tanks, I would have a shutoff valve on each tank. You may want to isolate them for some reason.

Good Luck,

Jim
 
   / What type of water tank storage tank? #6  
Polyethylene tanks will last indefinitely if you don't let trees or rocks fall
on them. There are 2 major grades of poly tanks, cross-linked
(PEX) and linear. The latter is cheaper and not a strong, but both
are superior to steel. Steel tanks are lined with a bituminous sealer
safe for potable water (Salinas Tank uses a water-based asphaltic
emulsion) to slow down the rusting process.

My own 5000 gal tank is poured-in-place concrete, sealed with the same
stuff Salinas Tank uses. At the time I built it, the cost to place a
pre-built tank was $1200/hr for a helicopter (the only way to access
my steep slope).

As for 2 2500s vs one 5000, I would lean toward the former if the
cost is less. Be carefull when doing your plumbing that all exposed
pipes and valves are insulated against freezing or buried. Also
UV will eventually destroy PVC.
 
   / What type of water tank storage tank? #7  
Tom,
Dave is right that the polyethylene tanks might last forever? I am going to have it sit on a concrete pad instead of sand or gravel mostly in the event of required maintenance, and working on a clean environment around it.

Whey is the single larger tank more expensive than 2 smaller ones? My guess would be the mold to build the bigger tank is more than twice the cost to build for a smaller one. They are so big that you have to step up to machining centers that can handle exceptionally large pieces of steel or aluminum that are out of the norm. Material to build the mold is also out of the norm as larger chunks are used instead of commonly found smaller billets. On top of that, the molding injection machine it goes into has to be more than twice as big to get the clamp and shot capacity. So manufacturing and quality control costs are way up there for the larger ones.

They sell them because many find it easier to deal with one tank rather than 2 (bulkiness aside) regarding plumbing and such. In some cases, the foot print is the same for larger tanks as on a smaller tank when space an issue. I don't know about the ones you are looking at though? I know the 10,000 gal ones I looked at were either the same diameter or only slightly larger than the 5,000 gal ones.
 
   / What type of water tank storage tank? #8  
I'd vote for the two tanks. Besides costing less two tanks would add a layer of redundancy to your system.

I used a single tank because I got it for free. Set it on sand and built a metal building around it to stop algae growth and add a level of security. Been fine for 20 years but if I had a second tank I'd periodically drain and clean one or the other. I have a layer of silt from the well that has built up on the bottom. It doesn't hurt anything and it's not worth draining my tank just to clean it because it'd take too long to get it full again.

Phil
 
   / What type of water tank storage tank? #9  
It has been years since I checked prices in N California, but the
cost of a 5000 used to be less than 2 2500s. There is a guy in
San Jose who delivers 5000 gal poly tanks on his compact Japanese
pickup. It is an amazing site to see on the highway, but he has
done it legally for years, despite being stopped many times by the CHP.
That tank is 8' diam x 6-7' tall, if memory serves.
 
   / What type of water tank storage tank? #10  
I just used a septic tank but only half buryed. Has worked for years.

mark
 
 
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