How high should I place the water tank?

[stumpfield]

How high should I place the water tank? I want to have gravity feed with enough pressure without rely on any pump. I know the higher the better but there's a cost to it. I don't want too much pressure. Just enough for a typical home. I guess that's between 40-60 psi??? The highest point on my property is about 150 feet above the house. Found some reference on a google search saying I get a theortical pressure of 43.3psi per 100 feet if there's no friction in the pipe. What's the realistic pressure if I place the tank 100 feet above the house? Thanks for you help.

[egon]

The statgic Pressure will be approximetly 43.3 PSI for 100 feet of elevation depending on your ground elevation and atmpospheric pressure.

Dynamic Flow Pressure will be affected by pipe size, flow velocity, pipe roughness factor and fitting losses. The amount it is lowered can be calculated but not by me! [img]/forums/images/icons/grin.gif[/img]

Pat's the fellow you are looking for. Just make sure he does not use the Square Radian Theroem as there are still some debates on it's application! [img]/forums/images/icons/smile.gif[/img] [img]/forums/images/icons/smile.gif[/img]

Egon [img]/forums/images/icons/grin.gif[/img]

[CJDave]

[img]/forums/images/icons/tongue.gif[/img] For typical flows found in domestic use, the friction losses would be manageable if you used a minimum of 1" pipe. If the line is also going to be used to fill the reservoir, that same friction loss is added to the pumping head due to elevation. You will want to BE SURE to have a "squish" tank at the house or the downhill pipeline will hammer the valves right off the dishwasher and the washing machine. A hundred feet of elevation at LOW TANK LEVEL is about as low as you'd want to go. That would give you, as Egon pointed out, 43 PSI when the line is at a zero flow condition. Somewhere I have a chart that gives the friction losses of fittings and expresses it in feet of pipe so you just add theoretical pipe length and get the total losses. My cousin did this very same project and used very heavy 1" PVC pipe because his water is pumped uphill....past the house....to a high tank......and then flows back down to the house. He has something like 300 feet of elevation to overcome when his reservoir is being filled by a piston pump from a spring. One final note......when you plumb the tank, you might consider having two different outlets, one at or near the bottom, and one a few feet above the bottom. Use the higher one as "duty" and the lower one as "reserve" that way when you run out of water at least you have the reserve valve you can open and water to use while you trouble shoot the supply problem. [img]/forums/images/icons/tongue.gif[/img]

[Buckeye_Jim]

Stumpfield,

I am building a very similiar system here in Nevada County. My tank is 2600 gallons and will have a float switch which will turn off the pump when the tank is full. For my system, the tank will be about 80 feet higher than the first floor of the house. The pipe will be 2" so as to have a greater flow if fighting a fire. I am also adding a 3/4" overflow pipe in case the float switch fails. One of my constraints is that my well only produces 3 gallons per minute and I am using solar power. The house is about 1100 feet from the tank. I am expecting the approx. 30 psi in the upstairs bathroom will work fine.

Jim

[stumpfield]

Hi Buckeye_Jim,

Is your well located close to the tank or you have to pump water uphill? I'm still in the planning stage. No well yet. Still not sure where the well should be located (or do I really have a choice???) I spoke to 3 well drillers, they all seem to not really want to recommend a well location. It appears to me they prefer where it's easier for them to setup their drilling equipment. I never have a well or have one drill. So, don't know how to deal with this. Since the well driller make their money from drilling the hole, not finding water. I'm not sure there's incentive for them to find the best location. LOL, they will make more money if we don't find water. We'll have to keep drilling deeper or a second hole. Is this a legitimate concern or am I just being paranoid?

[turnkey4099]

The depth of the well is a concern. You should be able to get a general feel for how deep it needs to go by checking with neighbors or the well drilling company should have the infor for your general area.

Yes they prefer to drill where it is best for their equipment but will IME drill where you want if it is physically possible.

They charge by the foot drilled (plus casing) so it is best to drill lower down if there are no other considerations.

Some people swear by, others at, dowswers. You takes your chance. I have dowsed 2 wells. some pipe runs and 2 septic drain fields but then here you will hit water no matter where you drill and the pipes were where logic said they should be. I have also dowsed things that aren't there.

Harry K

[stumpfield]

If I understand correctly, out here in the sierra foothills of california, there's no water table. It's all granite after 10ft or so below the surface. You get water by finding the cracks in the rock where water flows through. So, drilling in a lower area not neccessary better. I don't know if it's true, the drillers told me stories of drilling in a lower area found no water. Going up higher and found plenty of water.

I'm building in a very remote area. Only have 2 neighbors about a mile away and 1000ft below. They use spring water. No well. There are many springs with plenty of water at about 600ft below my building site (at the base of the mountain) on my property. I don't know if that's an indication of where the water level is. I wish there's a water expert whom I can pay a fee to find the water (with a greater level of certainty...) then get the well driller to drill on that spot.

Anyone here have gone through similar situtaion or have a well drilled in this area? I want to hear from your experience.
I hate to just take a chance. I'm usually not very lucky.

[Pat]

Trying to "FIND" water to be sure to drill in the RIGHT location in your situation could cost more than drilling a dry hole. Seismic exploration is expensive and NOT a sure thing.

There is roughly 14.7 PSI (standard atmospheric pressure, i.e. one atmosphere) for every 32.4 feet of water column. So 100 ft of water column is roughly 45 PSI. 32.4 ft of water is the height of a water column equal to the standard atmospheric pressure.

As regards frictional losses... There are no frictional losses when there is no flow so your static pressure will be determined only by the height of the water above the point of interest (shower nozzle or whatever.) I you want to do more than one or two of the following at the same time: run a clothes washer, a dishwasher, take a shower, flush a toilet, or whatever and not run out of water pressure so bad that you will be upset then you need to consider a larger pipe than 1 inch (at least for the main run. You can use 3/4 and even 1/2 for applications in the house with no problems but the main line needs some cross section to supply plenty of flow. Also try to design the main run from the storage tank to absolutely minimize the number of elbows.

Do take Dave's comments about water hammer, most seriously. You need to take measures to soften the blow. More height is better for the supply tank if you don't go too far overboard and create a tank filling problem. Consider a 10 ft high level change in the tank with the high point yielding 50 PSI. When full you get 50 PSI. Down 10 feet you lose aboiut 5 PSI and still have 45 PSI, only a 10% loss, no bit deal, not too bad. If you have only 30 PSI max and drop 5 PSI that is 17% and gets noticed.

My apologies to both you and Egon... I am fresh out of radians, square or otherwise but am expecting some any time now. I'll keep you posted.



[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[Buckeye_Jim]

Stumpfield,
Good advice from everyone, I can tell you a bit about the well. Here in Nevada County they record the statistics in a GIS data base and can tell you the depth and recovery rates of your neighbors wells. I had a neighbor who is about 200 feet in elevation above me and went down about 230 feet. My well was a nightmare. It was 680 feet, volcanic ash down to 425 feet, before we got to bedrock. Steel casing the whole 425 feet. Another neighbors has year around spring with way more water than he can use. Go figure. We were hoping to spend around $5K, but the well cost us $17.5K. That got us 3 gals/min.

The pump is a German Lorentz helical pump that will pump about 1.5 gals/min at a 750' lift. Water inside the well is only 300' down when were at rest. At that depth we'll pump up to 2000 gals/day with 500 watts of solar panels and a passive tracking system. All this has added another $8K in cost to the system. I am still not finished with the installation. Good luck with your project.

Jim

[CJDave]

[img]/forums/images/icons/tongue.gif[/img] Dear Stumpy, As long as this is still in the planning stage, don't miss out on ONE MORE POSSIBILITY, which is the tried and true "cattleman's method" of water supply, and that is: HORIZONTAL DRILLING. In Mariposa county, you have just as good a chance of finding water in a horizontal drill as vertical. Find a place with a good escarpment and drill into it. When the bit crosses a clay layer, the water will run out of the bore. You can see those little pipes sticking out of cut banks all along the highways which criss-cross the Sierra Nevadas. Caltrans puts them into cut banks to keep the water from popping out and sluffing the banks off and filling up the bar pit. Cattlemen are always battling the theft and vandalism thing, so not having a pump is a huge advantage. Sometimes a horizontal drill is just enough of a trickle to keep those cows in drinking water and the money saved by not having a pump can be spent in town on Saturday night at the H-B in Oakdale. YIPPEE!! Set 'em up again, Bachi!! [img]/forums/images/icons/grin.gif[/img]