What flow rate do you expect to use? Do you have a reservoir in the cabin so that the pipe only needs to slowly refill the storage over a ~24 hr period?
I have a receiving tank to draw from using a 12-volt electric pump. I only want to NOT restrict water flow because of too small diameter, along the 650 feet with 10-15 fall (head).
Here’s a calculator thingy that may be of use to you … I think I punched in your numbers correctly and came up with about 5 gallons per minute with 1" pipe … 32 gpm with 2" pipe …
[snark] Someone who grows pot on Federal forest lands might be able to answer your question better. [/snark]
Even a 20-foot pipe will restrict your flow. But since you have a cabin and not a municipality, you probably don’t need that much. watchwolf49’s calculator seems reasonable, and if you have a reasonably large receiving tank, 5 gpm seems like more than enough unless you’re also watering a garden. A family of 4 uses around 400 gallons per day, which is 0.28 g/min. A 0.5" pipe is enough for that.
Thank you. I found this site through forum discussion that involved laminar flow within different pipe, friction induced dead loss, and other fancy terms. Does anyone know about those terms affecting a 1" HDPE pipe at 650 feet?
Further, I am curious about pipe diameter reduction causing greater and greater velocities at the downhill outlet, as used by water hydraulic mining in the past. I would enjoy high velocity flow for fun, as it would be all powered by Mother Earth!
The old ranch house where I was born had a pipe that was shoved into a hill above the ranch house. It was a 2 inch pipe shoved into the hill, where it came out it was reduced to 1 1/4 inch steel pipe. The run to the ranch house was over 1000 feet. The drop over 40 feet. We had no holding tank. The water pressure varied according to how much water was being used. you were always readjusting the shower as it went to hot and cold. Sometime in the 90s my sister in law got tired of it. So my brother put in a pump and holding tank.
What’s the difference in material costs between 2 inch and 1 inch compared to the labor cost to install? I’d consider going as large as you can afford (up to 2 inch). 1-1/4 inch and 1-1/2 inch would be an improvement over 1 inch.
Don’t do this. Each transition is a point of possible failure, plus additional labor during install.
The problem is you’ve only 15 feet of drop … gravity can only accelerate the water so much … without any other force involved … the velocity will be whatever it is no matter the pipe diameter … now include 650 feet of pipe and friction will take her toll …
You can test the nozzle idea on your kitchen counter … see how fast the water comes out a length of 1/4" pipe … then see how fast with a 2" pipe, with a cap, and a 1/4" hole drilled in it … my guess is that the water velocity coming out will be the same …
Not exactly true, but sort of. The amount of water you get out of a 1" pipe 650’ long with a fall of 10’ is the same as you would get out of a 325’ pipe with a fall of 5’.
It follows that even if you have an infinitely wide pipe for the first 325’, you still get the same amount of water out of the second 325’.
There may be a good reason, or only bad reasons, for making the first 325’ wider than the tail, but if you have a straight pipe with even fall, increased flow is not one of them.
If you have a steep section, the natural flow /might/ be greater in that section, and the natural flow less in the flat section. Then increasing the diameter of the flat section would increase flow, and increasing the diameter of the steep section would not increase flow.
Something I haven’t seen is what volume your spring can supply, and you might want to size your delivery pipe based on that. There’s no point installing a pipe that will allow 20gpm flow with 15 feet of head if your spring can only produce 5gpm.
I also don’t see what kind of volume of water you’re planning on using, and if on a typical day you’re draining your holding tank. It would make sense to be concerned about flow rate into the holding tank if you need it to refill quickly because you use more than it’s total volume over a given period of time.
However, with 10-15 feet of head you don’t need to worry about the flow getting too restricted to actually deliver water by gravity to your tank. You need pretty small diameter pipe to actually prevent water flow through friction and/or surface tension, and as long as you don’t need more than your holding tanks capacity over a 24 hour period you should be able to use smaller diameter piping and have the water slowly trickle in through the day and night.
Also, the OP hasn’t mentioned any filtering … that might be the choke point for this flow …
I think this will work, very similar to the water supply we had in an old tobacco shed we lived in one winter down in Western Carolina … except we had about a fifty foot head and 3/4" pipe … as I remember heating it on the wood stove took the longer time that just drawing it …
Transitioning to progressively smaller pipe provides no real gain. That is to say making the pipe funnel shaped doesn’t help, except that the larger diameter will have less head loss than the smaller diameter.
The only time you would do that is if there were intermediate use points along the way, such that the first section was carrying more flow than the next, etc. OR if the spring feeding it were limited capacity, it would perhaps be better to store some water at the higher portions of the run…but at tank at the top would be the better way to do that, because pipes don’t hold very much…perhaps enough to flush a toilet though.
Static head will be set by the elevation change, and head loss under flow will be determined by the pipe diameter.
But in a lot of other contexts this is exactly the main point the OP ought to be thinking about. Electrical wire is pennies to foot still on the spool but dollars the foot inside the walls. The labor is all the difference.
Going cheap Charlie on materials when they’re barely 10% of the cost of a job is silly.
If you’re looking for higher water pressures that can be created by direct available head using gravity alone, you should read up on hydraulic ram pumps. These are a very old design that actually work by using simple valves and water hammer to capture/store pressure, and you can build them yourself and find designs and calculations on line. Unfortunately they only use a small percentage of the available water, and like most ancient designs we’ve vastly improved on performance and cost with conventional pumps. They still have applications in areas with the right combination of water volume, topography, and mostly lack of any external power source (aka 3rd world mostly… though there are companies in Australia who offer modern improved versions suited to some of their more remote areas), but if you’ve got a holding tank and 12V pump already you’re already beyond them technologically.
But with the set up you describe having, you get your actual water pressure at your taps from the 12V pump drawing from your holding tank, not the gravity feed piping system from the spring supplying the tank. As long as you’re not pumping out more water from that tank than the spring can provide over a reasonable time, you won’t get any benefit from using 10" over 1" pipe.
Where I am a quick online search gives me a price of maybe 50 cents per foot for 1" line, and the price seems to roughly scale up squared by pipe cross section area… so doubling the pipe diameter will cost you 4 times as much. If you need 650 feet of 1" that’s $325 just for the pipe. Going to 2" would bring that up to $1,300. Considering that in the described scenario the extra large pipe won’t produce any difference in pressure at the taps, I’d say you’d be wasting almost a thousand dollars. I’d be considering going even smaller diameter pipe than 1"… but again not enough details have been given so far to give a sure answer.
LSLGuy makes an important point, sometimes labor is much more costly than materials … but I’m not so sure that’s the case here … at $10/hr, we’d have 32 hours (or 4 days) to dig this trench … I don’t know, I think one man one shovel can do this in two days easy … of course depending on the soil type …
I once bid a job that included a mess of excavating in a really really tight place … the customer called me saying I forgot to include the huge expense of getting a backhoe into the work site area … [giggle] … I got the job and, yeah, the customer was truly shocked how much dirt one man one shovel could move in a day and a half …