Considering a gravity fed water pipe for the farm

johngalway

This bugs me, so I'm considering solutions and need some opinions.

Usually there is enough water for the sheep in the drains/stream. My holding is split in two. Rough grazing is higher, more grassy area is lower. Think of it as a blunt wedge, the high part is wider than the low part.

The rough grazing is where the ewes and lambs (those not on the commonage) are now, as I'm spraying rushes down below, tomorrow I'll need to start carrying water up to them as the drain there has stopped flowing.

Outside my top wall on the commonage there's a lake which Google Earth tells me is at 60m above sea level.

The lowest section in my rough grazing lies at 57m asl.

The lowest section in my grassy section lies at 45m asl.

I have some needs and wants.

I need to get water into my rough grazing. Two reasons, to water the animals there in dry spells without carrying the damn stuff uphill, and I'll be spraying off creeping gorse at some stage so will need water for that. I'd like to eventually have a storage tank there and also a drinker.

From the lake @60m asl to the low point in my rough grazing @57m asl is 310 metres. There is a high point of 67m asl 115 metres from the lake.

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I would like (this would be the want) to also have water at my shed which is the low point in the grassy section. This is roughly another 200 metres of pipe and would be 45m asl.

I've tried to do a bar graph here to show it a bit better.



The Green bar is the lake at 60m altitude
The Light blue is the high point at 67m altitude 115 metres from the lake.
The Purple bar is where I'd locate the tank/drinker at 57m altitude and 305 metres from the lake.
The Yellow bar is the shed at 45m altitude and 504 metres from the lake.

Probably over explaining this But I have no expierence with gravity feeds!

All help appreciated.

ATB,

John

valtra2

hi i kinda of get what you are talikng about, i used to do a bit of this work in nz on farms over there all i say is use big bore pipe and only reduse size on branches of to troughs, also make sure you put a air release valve on the highest point,also make sure you have good clean and nerver goes dry inlet

valtra2

oh ya and also watch your bar pressure on the pipe on lower ground as bar pressure will rise, roughley at evey meter you drop you get 0.1 bar pressure so at ten meters you get 1 bar, then you get have pressure loss due to friction loss on pipe, smaller pipe you loes pressure over long distance so that why use bigger bore pipe, sorry might not be explaning that well but if you have any quistions please feel free to ask

johngalway

I'm starting off with a 0 base of knowledge really. What I had thought of doing was puting a 1.5 inch pipe from the lake to the high point and then reducing it to inch to the tank. Or even inch at the lake going to half inch.

My mates Dad get's water from the same lake, I must ask him but he's laid up in hospital at the moment.

There wouldn't be huge demand on the supply to be honest, the most important aspect is just having water physically there when needed.

I may just go as far as the low point in the rough grazing to start out with and see how that works.

The idea of an air lock is a worry!

pakalasa

Yep Valtra2 is right.
You have a max drop of 15 Meters (60-45), so a potential pressure at your lowest point of 15 x 0.10 = 1.5 Bar (21.5 psi).
The problem is how do you get the water flowing over the hill. You'll have to siphon it. The easiest way is to pump water up from the lowest point untill all the air is out of the pipe. The water should then flow back down itself under gravity.
If any air gets back in, you'll have to purge it again, so any leaks in the pipe between the lake and the first hill and you'll loose it.
If you cant pump water up, then put a valve at each end and purge the air at a water tap elsewhere. Open both valves when the pipe is in place.

It should work, me thinks.

LostCovey

pakalasa wrote: »

Yep Valtra2 is right.
You have a max drop of 15 Meters (60-45), so a potential pressure at your lowest point of 15 x 0.10 = 1.5 Bar (21.5 psi).
The problem is how do you get the water flowing over the hill. You'll have to siphon it. The easiest way is to pump water up from the lowest point untill all the air is out of the pipe. The water should then flow back down itself under gravity.
If any air gets back in, you'll have to purge it again, so any leaks in the pipe between the lake and the first hill and you'll loose it.
If you cant pump water up, then put a valve at each end and purge the air at a water tap elsewhere. Open both valves when the pipe is in place.

It should work, me thinks.

It will work fine John if you bury the pipe in as straight a line as possible, we did the same thing, and it worked for over twenty years. What I mean about the straight line is that if you put a 'hump' in the pipe (e.g. over a rock in the trench), that is where you will get airlocks. Also, remember to put a couple of settlement tanks (to trap silt) and a mesh filter over the upper end of the pipe. One of our blockages in the early days was caused by a frog!

Lakes are tricky because levels go up and down, and there is often a muddy bottom. Consider damming the outgoing stream as a way of getting a reliable level, from which you can direct the water to settlement tanks.

Also remember that an open tank is a serious drowning hazard for kids/animals, so either keep it shallow or fence it off. We put several cross-walls in the collecting tank, so water went from chamber to chamber, and there was hardly any silt ever in the third tank. We put the inlet point about half way between the bottom of that tank and the surface.

I know a guy who has a big differential like yours and uses the flow from the pipe to drive a small turbine. More novelty than any thing else but it runs some lights.

LostCovey

johngalway

The pipe won't be buried, it can't be in a lot of spots as the bedrock is real close to the surface so I'd be a busy fool doing that. In deep ground it'd have merit, frost protection and such.

The settlement tank and filter are good ideas, thanks for those I would have copped the filter but not the settlement tank.

I was thinking of a closed tank, 1000 litre IBC tank or such can be picked up for small money. Not sure how good they are for drinking water mind. Mates Dad sunk a block, tied the pipe end to it and a buoy on the end, keeps the pipe off the bottom.

Do you know what pressure the lad running the turbine has, it's an interesting idea. I've no leccy in the shed and it'd be handy for lambing time!

LostCovey

johngalway wrote: »

The pipe won't be buried, it can't be in a lot of spots as the bedrock is real close to the surface so I'd be a busy fool doing that. In deep ground it'd have merit, frost protection and such.

The settlement tank and filter are good ideas, thanks for those I would have copped the filter but not the settlement tank.

I was thinking of a closed tank, 1000 litre IBC tank or such can be picked up for small money. Not sure how good they are for drinking water mind. Mates Dad sunk a block, tied the pipe end to it and a buoy on the end, keeps the pipe off the bottom.

Do you know what pressure the lad running the turbine has, it's an interesting idea. I've no leccy in the shed and it'd be handy for lambing time!

No I don't know the pressure, nor the exact height differential to be honest. Will try to find out.

However he came up with a clever alternative to burying the pipe, which completely avoids frost - he ran the pipe down in the bed of the stream, just put rocks or a bucket of cement on it to tack it in a few places. This may not suit you if the stream doesn't run in the right place.

LC

blue5000

just a couple of things to add, use a fairly fine filter. Fish do a right job at blocking a ballcock. Dung or sand over the pipe might also stop it freezing

johngalway

I was just checking other bits of land with Google Earth earlier and the altitude wasn't correct on them. Going to have to take a walk out to the lake with an altimeter to make sure or could be an expensive mistake!

Bog Man 1

Just a few pictures of our gravity water supply that fills a tank that we use for spraying it also supplys a few drinking troughs, and by manipulating a few gate valves can supply the yard taps with water. In an extreme emergency it could also supply the house but I would be reluctant to drink it. It fills the sprayer tank at about 1000 Gals an hour. The stream covers everything with a layer of lime which causes its own problems. The pipe diameter is about an inch an a half.But go for as big a pipe as you can afford and then go bigger.This system has been working for us for more than thirty years so it is a long term investment. We had problems after the last frost when all the lime on the inside of the pipe dislodged and blocked the pipe. The pipe is laid on the bed of the stream so it is unusual for it to freeze.