RickB
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Still the best answer.
Good vs Poor Wells - What makes a well a good well?
- Thread starter Pettrix
- Start date
Still the best answer.
cat fever
Elite Member
I agree with this post as well as Egon's.
My well is 180' deep with the pump at 156'. The drill truck was pumping over 100 GPM with no draw down on the well. My area sits on a giant aquifer so geology plays a big part.
CurlyDave
Elite Member
Whenever the discussion turns to wells, I always like to start an analysis from the back of the water supply issue.
We have a 4 bedroom house and the county required a 350 gallon per day septic system. The county standards are that we could support 8 people with that septic system. This is a flow rate of just under 0.25 gallons per minute.
We only have two of us, and our actual water use, with no attempt at conservation is about 175 gallons per day, which would be 0.125 gallons per minute.
If you are not going to irrigate, I would put the minimum acceptable flow rate at 0.12 to 0.25 gpm for a residence. Now with that low of a well flow you will need a cistern to provide some temporary reserve capacity.
Our well is about 2.5 gpm, we irrigate about 1/4 acre, and we never have any issue with water quantity. We flush toilets, take a shower, and run the washing machine, and irrigate at the same time and have never even notice any flow restriction. The standard for the well test is to pump at full capacity for 1 hour and then measure sustained flow after that. We get around 7 or 8 gpm for the first part of that hour, and then the flow drop off to a sustained 2.5 gpm.
I do have a storage tank for irrigation, which is by far the biggest user, and restrict the input to 1 gpm and have zones to limit the total flow to irrigation from the tank to ~ 2.5 gpm. The cistern is about 500 gallons, and we only irrigate for about 1 hour several times per day, which allows the tank time to fill.
I had heard the 5 gpm rule of thumb before we started and paid dearly for it. The first well we drilled, in search of 5 gpm was ~ 700' deep and still only produced 2.5 gpm. The pump failed at an age of about 8 years because the bore collapsed due to poor strata at that depth. The majority of the flow came in at about 250 feet. We had to drill a second well which I stopped at ~ the 250 foot level, and we are much happier with this well.
FHA and most banks have gotten away from the old 5 gpm "standard", and will now loan on almost any reasonable well.
If your well produces good-tasting water it is vastly more than sufficient at 20 gpm. That is about 100 times more water than you really need.
Turbys_1700
Elite Member
My water is supplied by a surface spring that has been in use by my family for over 200 years. I have no idea how much flow it has. We've never run out even during our worst drought 12 years ago or so. We've not had a lot of houses built close to the farm over the years and I guess the water table has remained stable. I have a small pressure tank and a spring box with a foot valve running into the spring house. Guess the water is OK since crawdads stay in there. I tell everyone that the water was so bad that it killed my great grandfather at the age 94. Never had it tested but I can't stand the taste of treated water.
oosik
Super Star Member
Hey, Turby - sounds a lot like my water supply. Its a spring, used by the original homesteader, starting in 1892. I upgraded it with cast,perforated cement rings to a depth of 16 feet. I surged it for 48 hours to reduce the silt & sand - dug with a tracked back hoe. Installed a 6" trash pump - pumped continuously for 48 hours - every hour I went down and "stirred the pot". After 48 hours of continuous pumping, the surface water level had not dropped an inch. I have a 3/4 horse submersible pump with a standard 60 gallon bladder tank, up here in the basement. The spring is around 150 feet from the house - down in the valley.
Never had it tested, however the little green frogs seem to like it just fine. It goes so very well with JD and a few cubes.
Never had it tested, however the little green frogs seem to like it just fine. It goes so very well with JD and a few cubes.
Turbys_1700
Elite Member
I figure as long as crayfish can live in my water it's OK to drink. Same with yours and the green frogs. I've got a few of them too. When you think about it the spring self cleans since it is constantly running. My grandparents used to keep milk in the spring house prior to electricity to keep it cool. About 10 years ago the county ran water past the house and wanted 2K to hook up. I passed. If my spring goes dry then I'll have to due to county ordinances unless I am 500 feet from the line. Think I am OK though.
crackerjack222
Silver Member
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Pretty much anything in the water can be filtered out.
Valveman, I would appreciate your comments on my situation:
I have a well on my ranch, SE of San Antonio, 700' deep, 5hp pump set at 360" in 4" pvc casing. The static level measured 20 years ago when it was drilled was ~50'. The pump will make about 40 gpm all day long. the problem: it has always made sand, a lot of sand. I call it sand, but it is a grey powder when dry. It will go through a "Whole House" filter with paper cartridge. There is so much sand it would be useless to put a finer filter because it would fill up in minutes. I can turn the pump on discharging on the ground thru 2" pipe and for the first ~minute the water will be clear as the pump draws from the casing. After about 1 minute the water turns gray with sand, then slowly clears up after 30 minutes to an hour. At one time I put the pump on a timer to cycle the pump on for an hour every 4 hours. After a few days of this there was not so much sand, but after sitting for a few days we were back to the same problem. Originally, I wanted to use this well to irrigate a large garden but the water is too bad (high TDS and salt) for that. I now use the well only for a bunkhouse and use bottled water for drinking.
I am considering two possible solutions, either replace the pump with a smaller one, say 1 hp, or put in a ~1000 gallon settling tank and pump out of that from about half-way down with a jet pump. My thought is that the smaller pump will not draw (as much) sand from the bottom of the well. The settling tank would likely only be partially effective depending on how soon water was drawn from it after the well pump had topped it off.
If you have any suggestions, I am all ears (or eyes in this case).
Valveman, I would appreciate your comments on my situation:
I have a well on my ranch, SE of San Antonio, 700' deep, 5hp pump set at 360" in 4" pvc casing. The static level measured 20 years ago when it was drilled was ~50'. The pump will make about 40 gpm all day long. the problem: it has always made sand, a lot of sand. I call it sand, but it is a grey powder when dry. It will go through a "Whole House" filter with paper cartridge. There is so much sand it would be useless to put a finer filter because it would fill up in minutes. I can turn the pump on discharging on the ground thru 2" pipe and for the first ~minute the water will be clear as the pump draws from the casing. After about 1 minute the water turns gray with sand, then slowly clears up after 30 minutes to an hour. At one time I put the pump on a timer to cycle the pump on for an hour every 4 hours. After a few days of this there was not so much sand, but after sitting for a few days we were back to the same problem. Originally, I wanted to use this well to irrigate a large garden but the water is too bad (high TDS and salt) for that. I now use the well only for a bunkhouse and use bottled water for drinking.
I am considering two possible solutions, either replace the pump with a smaller one, say 1 hp, or put in a ~1000 gallon settling tank and pump out of that from about half-way down with a jet pump. My thought is that the smaller pump will not draw (as much) sand from the bottom of the well. The settling tank would likely only be partially effective depending on how soon water was drawn from it after the well pump had topped it off.
If you have any suggestions, I am all ears (or eyes in this case).
Egon
Epic Contributor
Clay particles.
oosik
Super Star Member
CrackerJack,
It may be worthwhile to have a well driller look at your situation. If you aren't bottomed in a clay layer, he may be able to surge the well and pump out the majority of the silt & clay. They have the equipment to put a LOT more force into the well and draw the fines out from a long way around the intake.
It may be worthwhile to have a well driller look at your situation. If you aren't bottomed in a clay layer, he may be able to surge the well and pump out the majority of the silt & clay. They have the equipment to put a LOT more force into the well and draw the fines out from a long way around the intake.
Valveman
Platinum Member
It is always better to solve the original problem when you can by cleaning or developing the well. But surging or blowing a 700' well will not be cheap, and is not guaranteed to work. Reducing the flow rate could help lower the amount of clay you are getting. But you still need enough velocity in the drop pipe to get the fines to come out the top of the well. When you have too little flow in too large of a pipe the velocity will not bring up the sand. It will just settle to the bottom until there is enough to hold the check valve closed. So if you switch to a smaller pump, you should also switch to smaller pipe.
The reason the water first comes out clean is because it has had time to settle in the drop pipe. This is a good thing because at least the stuff will settle. Stuff that stays suspended in the water is hard to get rid of.
You could use a gate or ball valve to throttle the output of the pump to about 20 GPM, which is about as low as you want velocity in 2" pipe. Then I would use two smaller storage tanks instead of one. Bring the well water into the first tank about half way down. And bring it in with large pipe to slow the velocity. Then let the first tank overflow into the lower half of the second tank. You should draw pretty clean water from the upper half of the second tank. But you will need a booster pump to supply this water to the house.
Another idea would be to test the well with the existing pump. You can safely pump a 5HP at flow as low as 3 GPM. What you want to know is the water level in the well while drawing say 5-10 GPM for a long period of time. If the water level only draws down to say 100', then you could use a much smaller pump, set at a much shallower setting. Drawing lower flow from higher up in the well may allow the fines to settle in the well, and never get to the pump. If water is only used for the house, a 3/4HP, 10 GPM sub could be set at 120' and would produce 10-12 GPM at 50+ PSI.
I have also done wells that no matter what you did they would make fines for a while after they were started. In one case we set up a little 1/2HP pump to run all the time. We just used a modulating pressure relief valve and dumped anything over about 75 PSI. In this case there was a stock tank where the water could go and be used. So when the house was not using water the pressure relief would dump 2-3 GPM to the stock tank. When the house used water the pressure would drop below 75, the pressure relief valve would close, and the house would have 8-10 GPM available at 50 PSI. When the house stopped using water the pressure would increase to 75 and the relief valve would again dump water to the stock tank. In this way the pump never shut off and therefore never made sand, unless starting back up after a power outage.
The reason the water first comes out clean is because it has had time to settle in the drop pipe. This is a good thing because at least the stuff will settle. Stuff that stays suspended in the water is hard to get rid of.
You could use a gate or ball valve to throttle the output of the pump to about 20 GPM, which is about as low as you want velocity in 2" pipe. Then I would use two smaller storage tanks instead of one. Bring the well water into the first tank about half way down. And bring it in with large pipe to slow the velocity. Then let the first tank overflow into the lower half of the second tank. You should draw pretty clean water from the upper half of the second tank. But you will need a booster pump to supply this water to the house.
Another idea would be to test the well with the existing pump. You can safely pump a 5HP at flow as low as 3 GPM. What you want to know is the water level in the well while drawing say 5-10 GPM for a long period of time. If the water level only draws down to say 100', then you could use a much smaller pump, set at a much shallower setting. Drawing lower flow from higher up in the well may allow the fines to settle in the well, and never get to the pump. If water is only used for the house, a 3/4HP, 10 GPM sub could be set at 120' and would produce 10-12 GPM at 50+ PSI.
I have also done wells that no matter what you did they would make fines for a while after they were started. In one case we set up a little 1/2HP pump to run all the time. We just used a modulating pressure relief valve and dumped anything over about 75 PSI. In this case there was a stock tank where the water could go and be used. So when the house was not using water the pressure relief would dump 2-3 GPM to the stock tank. When the house used water the pressure would drop below 75, the pressure relief valve would close, and the house would have 8-10 GPM available at 50 PSI. When the house stopped using water the pressure would increase to 75 and the relief valve would again dump water to the stock tank. In this way the pump never shut off and therefore never made sand, unless starting back up after a power outage.