How to relieve air in spring-fed water line?

I agree that sediment is much more likely to be the issue. Since there is a tank at the house, my solution would be to rig up a backflush system. At the spring, I would install a backflow preventer and just below that an open ended standpipe aimed away from the spring. At the tank at the bottom of the run, I would install a pump, like a Harbor Freight 3/4 HP clear water pump, and a couple valves. When the water was slow, I'd throw the valves so water from the tank would go through the pump and into the line going uphill, and power on the pump. The backflow preventer at the top would prevent the spring from being contaminated and the stand-pipe would have a fountain of dirty water coming out of the top. Shut the pump off, and flip the valves and the water would then flow normally again. Total cost of the rig would be about $100.

I wouldn't think most pumps would be able to handle 200' of lift.

I wonder if it's possible to bring an air compressor tank filled to 100 psi and hook it up to the outlet and try to force air up the line to dislodge the sediment?

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Even if one couldn't do it alone, pumps can be ganged together, one after the other. Say that each pump has a 160' lift capacity; the first pump would pressurize up to the 100'+ level (allowing for de-rating) and the second do another 100'+ on top of that. The effective pressure on the pump impeller is only the difference between input pressure and output pressure.

I supplied creek water to our garden using such a system one year.

It would be much easier to pump down if the pumps are gas powered but I still think there must be a way to shock the sediments in the pipe loose if that is what is causing the problem. Just lifting the intake out of the water should allow the pipe to nearly empty assuming it has high spots.

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"Do you believe in the devil? You know, a supreme evil being dedicated to the temptation, corruption, and destruction of man?" Hobbs
"I'm not sure that man needs the help." Calvin

A jet pump would do 200' easily.

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Thanks for everyone's suggestions.

Looking at a topo map, I do believe the drop is 200' from the spring to the water tank. Another 30-50' from the tank to the cabin.

The pipe is 1" black sprinkler line PVC. Nothing special about it.

There are a few places where there are some high points, just barely. It is downhill most of the way but not all the way. Is that part of the problem?

No. with that kind of drop and and inch pipe there should be no problem with the (directly) with the flow. There might be a problem with sediment. Again, the best bet to keep the sediment out is to make sure the flow doesn't stop.

There may be a possibility, that if the spring is high in calcium or other minerals that is is adhering to the inside of the pipe. I don't know how well minerals adhere to black plastic, maybe someone on here does. If that is the problem, I don't think you are going to get it out easily.

If it is "loose" sediment, make sure there is an overflow down at the top of first tank so the water can continuously flow once the tank gets full. Since it works fine sometimes, I doubt if there is calcium adhereing to the inside of the pipe, but I guess it is a possibility. Sure the pumps or the compressed air would likely work for loose sediment, but why make something more difficult or expensive than necessary. If you have the tank full, pull out the feed pipe and let the water run out on the ground for several hours. It may take some time for the sediment to clear.

You only need a pump that will overcome the pressure from the drop in elevation. A pump that will do about 90 psi or greater will reverse the flow if the amount of drop is 200'. I'd go with a higher pressure pump to be safe if you're going to backflush the line. Make sure no air can get into the line from the downhill part of the system.

Still asking, does the water run all the time or does it shut off. If it shuts off, you could be getting an air bubble at the high spots. It will cause the water to run slower. Air expands much differently than water. An air relief valve will cure this. Does the intake ever get air in the line, (water flows faster at some point than comes into springbox) make sure it is submerged good....James

After dealing with to small of lines in my irrigation system and spring system I dug up everything and put 3" everywhere possible. Its amazing how much water can flow through that size gravity fed.

Makes a huge difference...

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The water does not flow full speed 100% of the time. It's a natural spring in the Colorado mountains, so the flow rate is dependent on how much water is coming down off the mountains from the Winter. We only visit the cabin during the summer. During the winter I would imagine the flow from the spring is quite minimal. So there is a great chance that the pipe is in-fact near-empty during the winter. The cabin is under 20-30+ feet of snow during the winter and is inaccessible, so I really couldn't be certain since I haven't been there during Winter.

During the time we are not there, we have various valves that we flip so that the water line bypasses the holding tank and cabin, thus allowing the water to freely flow through the pipe and exit the other end, thus keeping the water from holding still in the pipe and eventually freezing over winter and cracking the pipe.

I fixed a similar system for a lady in the mountains of NC. Initially I would have to make to trip to her place to get the system restarted every few months when she would call with the issue. She told me that the system always had this problem and that her late husband would sometimes spend days attempting to get the system flowing. Air pockets and sediment were the conclusion I came to as the cause. This lady had utility power but depended on gravity water and she did not want a pump due to freezing as she had frequent power outages in the Winter. All I had to do was install, at the house, a tee in the down hill line. The down hill line was plumbed into the inlet of the Tee, the side outlet of the tee and the remaining tee opening got ball valves. When the system ceased all she had to do was close the outlet ball valve feeding her cistern and open the ball valve that was plumbed a recycled tank with a shop vacuum mounted on the top of the tank. With the shop vacuum pump powered on the down hill line was powered siphoned with the water going into the recycled tank. This method would clean the down hill line with the trapped water washing out the line and at the same time get rid of the air trap. The recycled tank has a drain in the bottom for emptying said tank.. This "system" worked flawlessly and the elderly lady could do it herself! She certainly was appreciative and I got enjoyment from her excitement. If visitors dropped in I think she showed her water system to all of them. She liked her independence!

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Agmantoo
If they can do it,
you know you can!

I am wondering if air is getting into the line because of low flow in the summer. It depends on where these high spots are in the line (elevation) as to the flow being slower at times. There may be more flow than the spring is producing, thus inducing air in the line, collecting at the high spots and decreasing flow (suction)....James

My system in WV was very similar to the OP's. Sometimes the system would quit siphoning and only be running at a normal flow. I had the cistern 100' above the house, and 300' of 1" line coming down. The fix was to not use any water for a while, let the pipe fill up and then open it wide open to get the siphon going again. When operating as it should it would fill a five gal. bucket in just a few seconds. I don't know what the pressure actually was, but it was strong. I was careful of creating a water hammer, and was careful to instruct others to as well.

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Vicker
If you're born to hang, you'll never drown.

I have spring here at my cabin and it used to have a 3/4 poly waterline. There are no flat or uphill spots in it though. It has always worked well. I now have a 2" line because it feeds my microhydro generator. I flush the line once a month, open a 2" bypass valve and let it run for 20 minutes. In late summer it loses a lot of flow because the 2" waterline will flow more than the spring can deliver. I close it down slowly to let it build pressure to get the air out. I don't have a tank, just free flow through the generator nozzles and what ever water I use for the cabin and animals. Good flow will remove the air, but if it sets with no flow the air will burp up the pipe to a flat spot and become trapped.....James