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Small Cabin Forum / Off-Grid Living / Building a water tower - Need idea's/forums to calculate pressure
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marker2010
# Posted: 6 Jun 2012 11:59
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Hey everyone.

So i'm looking to build a water tower to supply my cabin with water for two sinks and one shower. I plan on building the tower around 70-100 feet away from the cabin.

I'm just wondering if anyone knows of the forum's to calculate the pressure needed, and any tips?

I'm getting a 1000L barrel. I plan on making the tower around 16-20 feet high or maybe less.

Any suggestions would be much helpful.

Thanks,

TomChum
Member
# Posted: 6 Jun 2012 13:26 - Edited by: TomChum
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Here's the answer in gearboy fashion.

A cubic foot of water weighs 62.4 pounds.
A cubic foot of water is 12" x 12 " x 12" = 1728 cubic inches.

If you made 1728 one inch ice-cubes and stacked these 1728 one-inch cubes vertically, it would make a tower of water 1728 inches (=144 feet high) weighing 62.4 lbs.

The pressure created by that 62.4lbs on that one square inch at the bottom of the 144 foot column would be "62.4 psi".

144 / 62.4 = .43 psi per foot
So for every foot you go up you get .43 'psi'

16 x. 43 = 6.88 = 7psi from a 16 foot tower.
20 x .43 = 8.66 = 9psi from 20 feet.


If you want buzzwords, then you would say '16-20 feet of head'.
Or, you could say 16-20 feet will create 7-9 psi 'head pressure'.

Household water pressure varies from 30 to 80 psi. Most appliances like a washing machine expect around 40 psi and can be damaged by higher pressures. 45 psi can be considered 'normal' household water pressure.

So you are wondering if 7-9 psi will be OK? Yes for it will work perfectly for the sink (but probably too low for appliances or a yard sprinkler ) Considering how well a sunshower works with only about 2 feet of 'head' I think 16-20 feet should be perfect for the shower too, but you might have to experiment with different showerheads, like the 'rainshower' type with lots of holes. The pressure-loss from the tank being 100 feet away, the hose, plus all the elbows etc....at low pressure, might add up, I'd recommend over-sizing the hose, use one-inch hose to supply the cabin, then once in the cabin you can reduce down to 1/2".

If you are using a water heater, you might try to find specifications for the minimum pressure allowed. It might do weird things at low pressure, maybe belch steam? You may have to add a 12v pump just to feed the heater its required pressure.

mocabin
# Posted: 6 Jun 2012 17:14
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I have been working out the logistic for a silimar water tower as well. Bumps that I ran into.

20 feet in the air will olny give you betwen 10- and 12 feet of head. Which is only 4-5 pounds of water pressure at the the shower head you would have about 5-6 lbs of pressure at the sink. All of this is assuming you built on the ground (my cabin is on posts)

There are lower pressure water heater that will work for this low of pressure, and low flow shower heads that will work as well. an simple internet search will find what you need for these items

However the big issue it the bracing and legs of the tower. 1000 L of water will weight over 2,000 pounds. You will need to have the supports go several feet under ground, I was planning on 4 feet(not sientific, just an estimate). So if you want a 20 foot tower you will need supports that are 24 feet long.

insulating the tower and pipes so that they did not freeze in the winter was also an issue that i have been working with

Keep us updated on you progress, I had to put my project on the back burner, and thing you come up with I would be interested to hear.

silverwaterlady
Member
# Posted: 7 Jun 2012 06:16
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If you plan on heating the water for your shower with a on demand water heater you will need to have enough water pressure to ignite the pilot light.

Bzzzzzt
Member
# Posted: 7 Jun 2012 07:02
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Quoting: TomChum
but you might have to experiment with different showerheads



I just wanted to expound upon this idea. Quite a few shower heads these days are of the "water limiting" type. That means they restrict the flow to "save water." While that might be good if you have 50PSI and a virtually unlimited water supply, it's not so great when you have 5PSI and 5 gallons. Most of these have a hole in them less than half the diameter of a pencil to limit the flow of water. With the low PSI it doesn't "shower," It just trickles out. It's pretty easy to take something like a ¼" drill bit (or maybe slightly bigger) and drill that hole out to allow more water to flow through thereby allowing the shower head to work the way you think it should even with the lower pressure. When you have a limited water supply you don't want all of it coming out at once either so The smaller the hole the better. If you get it too large it lets too much water through and that can also be bad. Experiment with smaller drill bits first and try the results before moving on to something larger.

Just my 2¢

TomChum
Member
# Posted: 7 Jun 2012 10:48 - Edited by: TomChum
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Marker2010 (who's not a member) did not say whether water "is easy to get" at his cabin.

Good point about looking for the flow restrictor. I'd drill it out big and then use a valve to set the flow rate (like "back in the the olden days" ).

For a reference point, I've been using a 5 gallon sunshower, and have found that 5 gallons will provide 2 great showers or 3 good showers. The sunshower has a hose with about 3/8 inch hole, which is lots bigger than a pencil, but possibly not big enough to flow a rainshower type showerhead.

Quoting: mocabin
1000 L of water will weight over 2,000 pounds. You will need to have the supports go several feet under ground, I was planning on 4 feet(not sientific, just an estimate). So if you want a 20 foot tower you will need supports that are 24 feet long.


With one ton 20 feet up, you should build it strong enough to ENSURE it never falls.....

But if the tower has 4 legs, 2200 lbs is 550 lbs per leg. That's not a big number (IMHO) worthy of digging 4 feet deep. It depends what kind of 'dirt' you have, of course.

At my place I'd put it up in a large tree to ensure it never falls (with a couple vertical legs to the ground to hold the weight).

johng
Member
# Posted: 7 Jun 2012 22:14
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Quoting: marker2010
...I plan on building the tower around 70-100 feet away from the cabin.



is this tower above or below the cabin?

Bzzzzzt
Member
# Posted: 7 Jun 2012 23:15
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Tomchum: I built myself a shower using a fountain pump that goes into a 5 gal bucket with water that I've preheated. I ruined my first shower head by drilling out the hole too large and the pump emptied the bucket in less than a minute. I made the second one with a smaller hole and it takes about 8 to 10 minutes to drain the same 5 gallons. It also has a nice flow of water. Without drilling it out it would not spray enough water to really take a shower.

MO Cabin
Member
# Posted: 8 Jun 2012 01:11
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Another idea I was kicking around was to build a roof over the tower then connecting a water collection and flitration system to the gutters. This would greatly reduce the amont of water that you would need to bring down. Under the tower you could place a 1000 gallon tank to catch the over flow so you would not need to bring water down unless you have a sever drought

steveqvs
Member
# Posted: 8 Jun 2012 10:47
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wow, i think solar, a couple of batteries and an rv water pump is going to be way more cost efficient plus you would get the pressure you need. Unless you just like a challenge!

toyota_mdt_tech
Member
# Posted: 8 Jun 2012 14:01
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You want to actually regulate your pressure to around 40PSI. The more you go up beyond that, the fater you will wear through your fixtures and plumbing. The first item to corrode away is the aerator on the sink usually. 80PSI, you will have short lived plumbing fixtures and plumbing itself.

ILFE
Member
# Posted: 15 Jan 2018 11:15
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Although dated, a great thread.

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