# gravity feed water

Solar Expert Posts: 404 ✭✭✭
this might be a simple physics thing but......

Could the weight of 200 gallons of water in a tank and thru a 1 inch pipe 240 [email protected] 5% slope.. push water 8ft above the top of tank level in a 1/2 inch pipe
when it is inside of the house..??? in otherwards could it push enough to make water on the second floor ..at least with a small amount of
flow..??? The second floor would be above the tank by about 6-7 feet...

• Solar Expert Posts: 5,433 ✭✭✭✭
Re: gravity feed water

I don't think so...

I don't think you can get water to flow up hill with out putting some energy into it. The weight of the water in the tank is irrelevant, as head is head whether or not you have 20 gallons or 20 thousand.

Tony
• Solar Expert Posts: 3,009 ✭✭✭✭
Re: gravity feed water

In a word, no. The pressure at the end of the pipe will be roughly 0.86 pounds pressure per sq in, ignoring friction losses in the pipe when the water is flowing, for every 2 feet vertical elevation from the outlet, to the top surface of the water in the tank. Does not matter how much water is in the tank, or how big or small the tank, or the size of the pipe, other than a larger pipe will have less friction losses per foot than a smaller one. The weight of water in a huge tank is not upon the pipe, it's on the legs or whatever support is used to hold the tank off the ground.
You need a pump. No getting away from it.
Re: gravity feed water

240 ft * 0.05 slope = 12 foot fall?

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 1,393 ✭✭✭✭
Re: gravity feed water

Not sure you mean the tank is 12 feet above or below house. Assuming you mean it is 12 feet above then 12-7 = 5 foot head (about 2.2 psi). If the second floor is above the tank then you will have negative pressure. It has nothing to do with how many gallons in the tank, only height of the source above the outlet destination. Gallons of water in a tank only provide the volume of water.

A water pump feeding a tank with a pressure bladder will increase pressure. With the tank empty, the amount of air pressure you inflate the air bladder to is the lowest pressure of the output water. There is a pressure switch to turns on the water pump before the actual pressure drops to air bladder pressure to avoid totally draining tank which would cause water pressure to drop immediated to zero. The pump is providing the extra energy to increase the pressure.

One atmosphere of pressure is about 34 feet of water column. One atmosphere is also about 14.7 psi. So there is 0.43 psi per foot of water column height of water.

Hover dam at maximum water height of Lake Mead has a 590 foot head pressure above electric generator turbines (254 psi). Power gen capacity is this pressure times volume of water allowed to pass. Unfortunately Lake Mead is now so low due to lack of rain that they have to cut back generation to about 25% of maximum capacity to avoid over draining of lake.
• Solar Expert Posts: 157 ✭✭
Re: gravity feed water

Sure you can. Use some of the water to turn a water wheel, which can be coupled to a positive displacement pump that goes up to the second floor.

You'll probably need to dump 5 gallons or more of water through it for every gallon that makes it up there, but it would work.

I recommend just using a regular electric pump instead, though.:p
• Solar Expert Posts: 9,359 ✭✭✭✭✭
Re: gravity feed water

Water pumping water - Ram Pump
http://en.wikipedia.org/wiki/Hydraulic_ram
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• Solar Expert Posts: 3,009 ✭✭✭✭
Re: gravity feed water
mike90045 wrote: »
Water pumping water - Ram Pump
http://en.wikipedia.org/wiki/Hydraulic_ram

Haha Built one of those many years ago for a "poor widow" neighbor of mine, and also loaned her 1100 feet of pipe so she could water her garden. Worked awesome, but she had plenty of water in the brook to run the ram. Fall leaves would cause problems though, but by them gardening was over anyway.
BTW, turned out that the "poor widow" had far more money than I'll ever have. She didn't have to spend any of her income as long as she had fools like me convinced she didn't know where her next meal was coming from.
• Solar Expert Posts: 10,300 ✭✭✭✭
Re: gravity feed water

now that's a curiosity as to how you can loan somebody 1100ft of pipe.

i have a brother and sister in law like that. they have as much money as the rest of the family all put together does. (that encompasses 6 other incomes) they cry all of the time of being poor and the only thing they have to show for all of their money is a 15yr old car as that's the only thing they own. i gave up trying to figure out what they do with it, but they don't fool me any more.
• Solar Expert Posts: 3,009 ✭✭✭✭
Re: gravity feed water
niel wrote: »
now that's a curiosity as to how you can loan somebody 1100ft of pipe.

i have a brother and sister in law like that. they have as much money as the rest of the family all put together does. (that encompasses 6 other incomes) they cry all of the time of being poor and the only thing they have to show for all of their money is a 15yr old car as that's the only thing they own. i gave up trying to figure out what they do with it, but they don't fool me any more.
Haha Obviously Niel, you understand where I was
But after many years, I had enough, turned my back, walked away and never looked back. She was a user of many, par excellence!