Looking for design information on single-family use water tower. Example, info necessary to compute height for given water pressure.

-- Carl Glassmeyer (usnrr@impulsedata.com), November 14, 1998

Answers

Carl,

Go to your local Rain Bird Irrigation supplier and purchase the "Landscape Irrigation Design Manual". It is easy to read and understand. All the info you need is there including friction loss etc.

WAAHOO

-- WAAHOO (bobb@mtjeff.com), November 14, 1998.

The pressure at the bottom of a column of a substance is dependant on the density of the substance and the height of the column. Example: a liter of water is 1000 cubic centimeters, and weighs (approx) one kilo. If you take a pipe with a cross section of 1 cm and fill it with water to 1000 cm height - the pressure at the bottom will be 1 kilo per square centimeter - if you fill a tank at this height the pressure will still be 1 kilo per square centimeter at the bottom of the fall.

-- Paul Davis (davisp1953@yahoo.com), November 14, 1998.

In Australia they use gravity water tanks collected from rainwater - 1000 galls or more. This could work very well in a humid warm are of the U.S. also. Like the water tank in the movie "Tremors"...don't think I have ever seen on in the south though.

-- Laurane (familyties@rttinc.com), November 14, 1998.

Jade Mountain sells a smallish water tower, plus soft water storage tanks. Their people are great.

http://www.jademountain.com

The tower is in their paper catalog; I can't find mine right now or I'd give you the specifics. We were thinking of putting a soft tank in the attic, filling it up & then running hose down into our water pipes. Have to make sure the beams are strong enough, though.

Have you looked into hand pumps, etc?

-- Arewyn (nordic@northnet.net), November 15, 1998.

Don"t know much about water towers, but as an added thought my daughter in Dubois, PA told me last week that those in the recent earthquake area of PA and OH have been warned that they only have a 2 month supply of water because the water tables have been lowered. She advised me to store water even though I have just drilled a new well with handpump.

-- Betty Arnspiger (Barn266@aol.com), November 15, 1998.

Hey Y'all:

Some little things you need to know if you want a water tower.

1. Water facts; 1. Water weighs 8.333 lbs per gallon. (US gallon) 2. There are 7.48 gallons in 1 cubic foot of water. 3. The area calculation for a pipe size is - Pi times Diameter times .7854, (or Pi times Radius Squared which is the same lady in a different skirt). The result that you have will be the Square of the area as defined in whatever unit you use ( inches = square inches, feet = square feet etc,). The value of Pi is 3.1416... 4. A water tower is simply a large diameter pipe standing upright. (all you tech types - I know about cylinders and spheres being different, but these folks are just putting up a simple water tank. They aren't designing a damn rocket, so hold down the sniping, but PLEASE feel free to correct any errors in the thing, I really don't want to hurt anyone and I have slept a time or two since I last did this.). 2. To build (design) your water tank you need to know: A.. How many gallons do you want to store. B. Water is the only substance which expands when it freezes. That is why stuff gets broke when the water gets stiff. This is also why you really need to leave 15% of the tank empty, so there is expansion room. If you don't leave room you'll have a really big ice cube laying in your yard, right beside the pieces of the smashed water tank, and yes, it does, on occasion, get that cold even down here in "Cajun fun country", so I know most of y"all need to leave the room in the tank. Also, for your "so what" file, you can't compress water. Remember this when you build stuff involving water. C. You must have a vacuum breaker on the tank (a vent pipe so the tank won't cave in, or your water flow drop to a trickle, as you drain the water out. This obviously only applies if it is a closed tank. D. If you choose to have an open tank (cistern), you also need to know that: 1. You will have some very happy birds enjoying your water too. 2. Mommy Nature will fill your tank for you when it rains. 3. The rain water ain't potable.

4. Mosquitos will erect a shrine in your name and they will multiply faster than any rabbit you ever saw. So will a lot of other critters. Everything seems to have that "urge to merge". Also, every tree & bush for 20 miles around will start to shed their leaves right smack into your watering hole, the wind gods will help them do it. E. You really should have an idea of how full the tank is at any given time. 3. Regardless of which type you choose - it will be pretty obvious to one and all that you have it. It really is hard to disguise the damn thing unless you also enclose the thing in a building (an open top building if you want the cistern).

So: To figure how big the tank should be; You want to store 3000 gallons in a tank 6 feet in diameter? 6x 3.1416 x .7854 = 14.80 cubic feet. 14.80 x 7.48 = 110.70 gallons. So your tank will have 110 .70 gallons of water in it when the level is 1 foot deep. 3000 divided by 110.70 = 27.10 feet. So, just to hold the water you need a 27.10 foot tall tank.

But, remember the stiff water? O.K. so now we need 15% more for expansion, so you now have 31.88 feet tall ( that's [.85/1] x 27.10 ). So now you got yourself a 32 foot tall tank. But, remember that water weighs 8.333 lbs/gallon? You are looking at 25000 lbs of water weight here, so be sure that you have a hefty rated tank and shut off valve. And a very stable ground site for the tank.

I'm sure that Robert A. Cook can help you out with vessel ratings, pressures, standards, etc. He is an Engineer - I'm not.

Mr. Paul Davies gave the information on water pressure and flow rates in an answer above in this same thread. Just convert the metrics over to inches/feet and you are in business. I will only add that the specific gravity of water is 1.0000. It is the standard to which all others are compared.

The vacuum breaker and level indicator? Simple. Just tap( NOT DRILL ) a hole sized for a 1" pipe 1 foot from the top of your tank. Get yourself a length of 1/16" or 1/8" aircraft cable, or other suitable wire, that is 30' long. Thread the cable through the pipe nipple and a 1" 90 degree pipe elbow, I would use PVC or CPVC pipe myself since there won't be any pressure on it and it is cheap, attach a fishing float(bobber)that is about 3/4" in diameter to the cable, toss the float into the tank and then screw the pipe nipple and elbow assembly into the hole in the tank. Attach another fishing float, identical to, or of less weight than, the one inside the tank, to the end of the cable that is outside of the tank. As you fill the tank the cable will be pushed out by the float laying in the water, and as you draw down the water the float will sink thus drawing the outside float up the tank. Either way the float on the outside will be at the same level as the one in the tank when the tank is half full, and the outside float will move up as you drain the tank down (use the water) or down as you fill the tank up. You can just gently tug (lightly) on the wire to make sure that it isn't sticking and you have yourself a jim dandy little level indicator and vent/vacuum breaker system. The outside float will move the same amount of distance as the water level. So, if your float is 2' below the center of your tank, you can bet that your water level is 2' above center, or 18' of water. That's about 1993 gallons of water ([32/2 + 2] x 110.70 = 1992.6). It ain't pretty, and it ain't real accurate (it won't meet ANSI standards), but it works.

Plug in your own numbers and you can figure out how fat/tall you want your tank to be for XXX gallons of water.

Tap a hole in the tank where you want to fill the thing and screw a pipe nipple onto the tank. Screw a valve onto the pipe nipple and then screw on another pipe nipple to the other end of the valve. On the end of this nipple you attach a pipe tee using the center leg of the tee. With the tee pointing up and down you should have

A.) A hole on the bottom to attach your supply line to fill the tank.

B.) A hole looking up at the sky. Screw a pipe cap onto an 8" long pipe nipple and then screw the nipple into the top pipe tee hole. This is an "anti - hammer" dead end pipe. You need this so that you won't be trying to compress water with the trapped air that is in the pipes. The pipes will "hammer" because of the trapped air.

If you are filling the tank from a community water supply -- most city type water supplies are set to 30 psi pressure so allow for this in your guesses as to tank fill time etc. The reason that the pressure is this high is so that, if a water line breaks, the water will be forced out and therefore any contaminates in the ground won't be getting into the water supply. It is nominally 2 atmospheres(28.34 psi) pressure rounded up to 30 psi for convenience. For all the tech types - yep,I know about aspiration caused by the interaction between the molecules of a flowing surface etc., but this is just a very basic thingy on water towers. Remember? If you fill the tank from the muni. system - Remember to close off the fill valve when (if) TSHTF or you will become the new water supply source for the folks.

I hope you don't NEED the tank/cistern. But it really does work this way just in case you want to have one.

Mr. Davies: Thank you for your explanation of #2 in my post re the "Forecast Effect". I do appreciate your taking the time.

Mr. Cook: Thanks for the tour through "Nukie 201" in another thread. I enjoyed it very much. I just hauled the things around and wasn't too interested in them, but they are indeed fascinating at the level that you wrote about.

Take care and have fun.

S.O.B.

-- sweetolebob (La) (buffgun@hotmail.com), November 15, 1998.

Oh yeah.

I forgot to add something.

Tap a hole in the tank and install another pipe nipple/shutoff valve/elbow/nipple so that you can get the damn water out when you want it. This hole should be about a foot or so above the bottom of the tank so you have room for sediments to settle out before you draw the water.

With the fill valve closed you will be using "head" pressure and the vent system to cause the water to flow.

Also, wrap each pipe connection with Teflon (R) tape before you screw the things together and you will keep it all from leaking too. Teflon tape is the pretty white tape. You can find at Walmart, Kmart, hardware stores etc.in the housewares section or over in the plumbing section. It also isn't "sticky" tape so don't fret, the stuff will work, I used it for more years than I care to remember about.

And, obviously, I am not used to formatting stuff for posting or it would have appeared as neat and pretty as my copy of it did before I tagged the submit button.

I'm really having a Monday. I have seven of them a week nowadays.

Anyway, you folks can chop & channel the post as you need/want to make it legible. Or, of course, ignore it all.

It really was pretty before I sent it. Honest it was. I will own up to the outlet spout part. That probably wasn't my "sterling moment" in this. But, you can't beat the price.

S.O.B.

-- sweetolebob (La) (buffgun@hotmail.com), November 15, 1998.

Hey, sweetolebob, I liked everything about your response on the water towers except your arithmetic:). The formula including the constant .7854 was incorrectly stated, resulting in an error. You multiplied 6 times pi times .7854. When you use the constant .7854, you need to omit multiplying by pi - the constant includes the effects of pi - and you need to square the diameter.

My arithmetic comes out as follows: A 6 foot diameter tank has a cross-section of 3 ft squared times pi, or 3 x 3 x 3.1416 = 28.27. Also, 6 times 6 times .7854 = 28.27. This number times 7.48 gallons per cubic foot is 211.5 gallons per foot of height, not the 110 gallons you figured.

I believe that you get about 0.43 lbs of pressure per square inch for each foot of height of the water column. So if you wanted 15 lbs per square inch water pressure, you would need 35 feet height. If you have an acreage that is a little hilly, putting the tank at the top of the hill will save you some tower height, since all you are looking for is altitude higher than the spigot.

The tanks from the well at my cabin are about 50 vertical feet above the cabin, and the water pressure will just about knock your socks off (hard to keep the faucets from dripping). Small children get knocked over and drowned in the shower regularly.

Regards.

-- Dan Hunt (dhunt@hostscorp.com), November 16, 1998.

Dan Hunt;

You are very correct, and I was dead wrong.

I told y'all I had a Monday going on. I am very sorry for the screw up.

You folks use his math. Mine sucks. The rest of the tale is true though.

I have shame passing all over my face now.

I believe that I am the only living brain donor on earth.

S.O.B.

-- sweetolebob (La) (buffgun@hotmail.com), November 16, 1998.

S.O.B.

One question. What do you recommend to discourage "Boudreaux" (the previously mentioned 5 pound Louisiana State "bird") and his kinfolk from turning your cistern into a seaplane ramp?

BTW, save the "brain donor" stuff for those who don't know about the briar patch!

-- Hardliner (searcher@internet.com), November 17, 1998.

Hardliner;

I don't know yet.

I am still looking for a good idea that will still fill "potable label. I'm asking all the old folks hereabouts - so there is hope yet.

I will post it if I find something.

S.O.B.

-- sweetolebob (La) (buffgun@hotmail.com), November 18, 1998.