Gravity fed watering and fluid dynamics(?), and hose / fittings question

Not sure this is exactly a catchment question, but close enough?

I have a 3,000 gallon tank on small hill. I'd guess that when the tank is full, the top of the water is about 12 feet above the ground I want to water. (Would we say there is a "12 foot head"?)

I want to get a hose and fittings with a big enough diameter so that I get a decent water flow. Otherwise watering will take too long.

A couple of questions:

1 - If I have a hose with an ID (inside diameter), of 3/4", but the hose's fittings have ID's of 1/2 inch, do the fittings - in effect - make the flow rate the same as if the hose's ID was 1/2"? Put another way, is the fact that MOST of the hose has an ID of 3/4 allow for a greater flow rate even though the end fittings are only 1/2 inch?

2 - Does anyone know of anywhere I could buy 1" or 1 1/2", POTABLE, hoses and fittings? One thing I'm encountering is that most shut-off valves have smaller IDs than they let on

Hey Bert,

I have a 2500 gal tank just maybe 25ft above my garden than you. I doesn't have a lot of pressure but it works. 2.3ft of head is one PSI according to the internet. So i guess im looking at 10 PSI or so. It really sucks to water with 10PSI when it's 98 degrees out but I really like using rainwater in my garden.

As far as flow, I think no, nothing matters but the smallest diameter in your line. I could be wrong but I can't see how.

My best advise for fittings and such is just to go to the agriculture supply store and look at it all in person. Because you are right, manufacturers lie.

Bert Bates wrote:Put another way, is the fact that MOST of the hose has an ID of 3/4 allow for a greater flow rate even though the end fittings are only 1/2 inch?

The answer is yes. The larger diameter pipe has less internal friction, so the flow will definitely be greater.

Bert Bates wrote:2 - Does anyone know of anywhere I could buy 1" or 1 1/2", POTABLE, hoses and fittings? One thing I'm encountering is that most shut-off valves have smaller IDs than they let on

If this is a somewhat permanent installation, I would use a fat diameter poly water pipe in a shallow trench. Costs less than hoses and lasts forever. It's available at pretty much any serious hardware or farm store. Plumbing supply houses will have it also. Around here, the pipe approved for potable water is clearly marked and has a red stripe.

Personally, I find that the most time-efficient way to water (sans a drip line or soaker hose) is to run the water into an open tank (like a stock tank) and move it with two big watering cans. A cattle float valve prevents overfilling. Hoses are a pain to move around, crush plants and are slower, even with a pressured system. My shoeleather express can move a helluva lot of water in record time.

Hahahaha DAMMIT!!

Not counting friction!!!

Thanks for the feedback.

I could have added that I'm filling 4, spaced apart 10-20 gallon buckets for horses. no plants to worry about crushing. so the permanent solution won't work because it's best to drag the hose back and forth between horse buckets.

Ah! I thought it was for a garden. Guess what's on my brain these days.

How long is the run from your tank to the "watering zone?" Can you run a fat poly pipe to a central spot and then a 3/4 hose from there?

Industrial supply houses will definitely have larger diameter hoses. But it gets pricey pretty fast. I don't know about potable-friendly; I have no doubt it's available, provided your wallet is fat enough.

Douglas Alpenstock wrote:Ah! I thought it was for a garden. Guess what's on my brain these days.

How long is the run from your tank to the "watering zone?" Can you run a fat poly pipe to a central spot and then a 3/4 hose from there?

Industrial supply houses will definitely have larger diameter hoses. But it gets pricey pretty fast. I don't know about potable-friendly; I have no doubt it's available, provided your wallet is fat enough.

It's about 75 feet. I get what you're suggesting, and that might work, I'll have to think about that.

I guess the fluid dynamics are such that if most of the 75 is wider, a short section of 3/4" hose will restrict flow less than if the entire 75 foot run is 3/4"? That's starting to make sense..

I agree with Douglas.
But I would do the final few feet differently.
I suggest run 1 1/2 " from the tank down and past each required watering point.
I would fit a saddle at each watering point with a 1 inch riser, right angle fittings and a ball valve which can discharge directly into the water bowls.
Later you may get away with float valves hidden from the stock!

Bert Bates wrote:I guess the fluid dynamics are such that if most of the 75 is wider, a short section of 3/4" hose will restrict flow less than if the entire 75 foot run is 3/4"? That's starting to make sense..

Yep, you've got it. Pipeline Theory 101.