Water storage system for low yield well - help!

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bhlyw

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Hi, we're new to your forum and would like help designing a water storage4system for our home.

We have a 260' 5" well into shale that yields about 5 gal per hour. The pump is a 3/4 HP, 7gpm Goulds sitting at 235'. The depth to water at best is ~95' giving us storage in the well of 140 gallons. There are only two of us but we hate having to worry about running out of water. We'd like suggestions on how large a storage tank to add and where to add it into our current system.

In the basement we have a standard pressure tank at 40/60 and a Reactor Series water filtration system to help filter out the organic and inorganic Fe in the well water.

We're thinking of adding a 250 gal, non-pressurized doorway storage tank and are not sure how to go about it. Is that a good size tank for our needs? What are the benefits of a pressurized vs a non-pressurized storage tank? Where do we put the storage tank considering our current system?

Ideally we'd like to have a well that produces more water and eventually we'll probably try drilling a new well but for now we've got to live with what we have.

Thanx in advance for your help!

:confused:
 

Bob NH

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5 Gallons per hour? 120 gallons per day?!!

You might find that you can get more yield if you maintain the level at a lower level in the well. More on that later.

As for storage, 250 gallons is probably enough if you are now getting by without such storage. You can use a float switch in the tank to turn on the pump in the well. You should also have a switch in the tank to sense low level and protect the pump that you will use to pump from that tank to the pressure tank.

You will need a shallow well jet pump or a multistage centrifugal pump to pressurize your tank.

Maybe you have already done what I am going to describe below, but if not, you may be able to get more water out of the well.

If the water rises to within 95 ft of the surface then there is pressure in the aquifer corresponding to 140 ft above the pump; assuming that the aquifer enters the well at or below the pump. If you keep the water in the well pumped down to only 20 ft above the pump then there is always about 120 ft of pressure trying to recharge the well.

Your well pump could be operated with a Pumptec http://www.wwpp.us/pumptec/pumptec.shtml or other such device to protect the pump from pumping the well dry. That would allow you to maintain the level down nearer the pump and might increase the recharge rate.

The Pumptec would allow the water to be pumped down to where the pump runs out of water; then try again after a set period of time. You would set the time based on tests to see how long it takes to get a a reasonable amount (perhaps 20 gallons) of water above the pump.

Under normal conditions the pump would act as it does now. The Pumptec and pumping down to the pump would occur only if you are using more water than can be produced when the water is higher in the well.

You could test whether the such a plan would increase the yield.
1. Run the pump until you run out of water; then shut it off.
2. After 1 hour, run it again until it runs out of water, and measure the amount produced the second time.

The 7 GPM 3/4 HP Goulds pump is just adequate for pumping from 235 ft to a pressure tank but will work fine pumping to a non-pressurized tank. I am surprised that the well-driller would put a 7 GPM pump on a 5 gallon per hour well. I believe a 5 GPM pump would be a better fit.
 

bhlyw

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Thanx Bob!

We do have a PumpTec - I neglected to mention that.

Interesting thoughts about increasing production. Until recently we've just used water normally and only had issues when we did lots of laundry in the same day so your comments make sense - the more we use the more the well may produce to a point. 4 loads of laundry, several flushes and two showers does it in for sure!

Actually, the driller put in a 1/2 HP 7GPM pump at first and we went through almost 2 months of hell thinking we had no water at all. I finally figured it out after hours and hours of internet search and phone calls. My clue came from this forum! The pump simply was not capable of pumping the water.

So we get the new 3/4 HP 7 GPM next week and are looking forward to being able to access what little water we have. The 3/4 HP is rated to ~420' and our total dynamic head ranges between ~400' and 200'. We looked at a 5 GPM pump but thought the 7 GPM would keep the pressure more constant over short periods of pumping.

So, back to thoughts of a large storage tank... I'm afraid it will be dirty and nasty if we put the storage tank in before the water filtration system. We have about 0.5 ppm iron in our water. I don't want to have to clean the tank out regularly. Can we put the tank in after the filtration system so it fills with the already-clean water?

Thanx!
 

Southern Man

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I don't think well yield is the problem. 5gpm x 60 x 24 is 7200 gallons per day. I figure 150 gallons per person per day is a conservative (high) estimate of demand, unless you are irrigating. If you are running out of water either theirs a problem with the pump or that’s not your actual well yield.

See a similar issue here: https://terrylove.com/forums/showpost.php?p=144886&postcount=7
 

Bob NH

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Iron in the water is usually dissolved when in the well. It can't be removed by filters when dissolved.

When you put it in the tank it will become aerated and forms insoluble iron oxide. You may also want to occasionally add about 2 Tablespoons of unscented chlorine bleach to the 250 gallon tank to prevent any bacterial action in the tank. There will always be things getting into that tank. The bleach will also cause oxidation of dissolved iron.

If it were mine I would filter both before (remove the suspended solids such as sand and silt), and after it goes into the atmospheric storage tank (remove precipitated iron and things that will inevitably get into the unpressurized tank). You will have enough head available with the 3/4 HP 7 GPM pump to deliver water through a cartridge filter into the unpressurized tank.

The 3/4 HP 7 GPM pump will work fine with the atmospheric pressure tank. If you are considering using it with the pressure tank, you would be better served with the 3/4 HP 5 GPM pump. I looked at the curve and the 5 GPM pump delivers 4.5 GPM at 400 ft while the 7GS07 is at shutoff (0 GPM) at 400 ft, and delivers about 4 GPM at 360 ft. http://www.goulds.com/pdf/7310.pdf

You will also get longer filter life with the 5 GPM pump filling the 250 gallon storage tank. Filter life is based on pressure drop across the filter and the 5GS07 delivers lower flow at the lower head condition of the 250 gallon tank. It will also give you longer run times with the pump, which is good for the pump.
 

bhlyw

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Hi Bob,

Thanx for your insight.

Hum, if we pump into a non-pressurized tank that changes the head ranges significantly. From 400'/200' to 250'/115' and the 115' looks like it would be problematic for either pump. Is there a calculation for back pressure from an inline filter that needs to be added into the calculation? Yikes, this is confusing!

Of course, we're not ready to do the storage system immediately so until we are we need to be able to use the water system as is until we are ready to add the storage tank.

Hi Southern Man - we've got about 5 gallons per hour of well production, not 5 gallons per minute. That's 5 x 24! Well yield is for sure the problem. If we had more water available we'd just get a new pump and be done. Luckily I travel most of the week so its only an issue if I'm home and doing lots of laundry.

;)
 

Southern Man

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.....

Hi Southern Man - we've got about 5 gallons per hour of well production, not 5 gallons per minute. That's 5 x 24! Well yield is for sure the problem. If we had more water available we'd just get a new pump and be done. Luckily I travel most of the week so its only an issue if I'm home and doing lots of laundry.

;)


Wow! That's barely enough to drink!

If you can't get it out of the well you'll have to set up a cistern and collect off the roof. Plumbing Codes will govern what has to be done. You might be able to ease somewhat by having a separate supply system for washing/ flushing.
 

bhlyw

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Wow! That's barely enough to drink!

If you can't get it out of the well you'll have to set up a cistern and collect off the roof. Plumbing Codes will govern what has to be done. You might be able to ease somewhat by having a separate supply system for washing/ flushing.
You're stating the obvious... To this post and to the "To shock or not to shock" post.

That's why I'm asking all these questions about storage systems.
 

Valveman

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Even with a storage tank, your supply has to be as much as the demand. Only adding 120 gallons per day to storage will not help, if you use more than that everyday. Might want to use the money you are going to spend on storage tanks and booster pumps to find a well with a little more supply.

Otherwise 250 gallons of storage would give you a couple of days supply. My hat if off to you if you can survive on that small amount of water. Talk about conservation!!!
 

bhlyw

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Even with a storage tank, your supply has to be as much as the demand. Only adding 120 gallons per day to storage will not help, if you use more than that everyday. Might want to use the money you are going to spend on storage tanks and booster pumps to find a well with a little more supply.

Otherwise 250 gallons of storage would give you a couple of days supply. My hat if off to you if you can survive on that small amount of water. Talk about conservation!!!

Guys, guys, guys! I appreciate your concern but if you'd please read the beginning of this you will find that there are only two of us and we don't run out of water unless we flush and shower normally AND do 4 loads of laundry.

We DO plan on adding an additional well but we can't quite afford that yet and must live with what we've got for a bit longer. We've been doing just fine since last November. We only had problems 3 or 4 times and that was after multiple loads of laundry and not paying attention. I'd rather spend a couple hundred now and live a bit more comfortably for the next year or two.

Bob has given us some really helpful information here and I'd like to continue along that positive path. So, my question again:

If we pump into a non-pressurized storage tank, that changes the total dynamic head ranges significantly. From 400'/200' to 250'/115' and the 115' looks like it would be problematic for either the 5GPM or the 7GPM pump. And, is there a calculation for back pressure from the inline filter that needs to be added into the calculation?

Thanx!
 

Bob NH

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If we pump into a non-pressurized storage tank, that changes the total dynamic head ranges significantly. From 400'/200' to 250'/115' and the 115' looks like it would be problematic for either the 5GPM or the 7GPM pump. And, is there a calculation for back pressure from the inline filter that needs to be added into the calculation?

Thanx!

You can make either pump work.

If you consider the idea that the new pump might be moved to a new well that has more capacity but nearly the same head, I would select the 5GS07 pump. It will provide plenty of head while the 7GS07 will be marginal for the deepest drawdown.

If the flow is too great at low heads (high level in the well) you can throttle the flow with a gate valve in your open tank setup. If the filter is on the supply to the tank, you would put the valve on the inlet side of the filter, and tighten the packing nut and take the handle off after it's adjusted so it is not inadvertantly closed. With the 5GS07 pump the valve will be set so there will be about 30 psi pressure loss across it when the flow is 7.5 GPM. At 5 GPM the pressure loss across the valve will be about 15 psi.

With the 7GS07 pump you would throttle the valve down to have about 50 psi pressure drop at 10 GPM.

As the water level goes down in the well the pump will operate along its curve at reduced flow and the pressure loss across the valve will become insignificant.

The pressure loss through the filter will vary from zero to about 30 psi, which is well within the range that the pump will handle.

You are trying to operate the pump to deliver a small average flow from the well, so throttling it when pumping into the tank is not a problem.
 

bhlyw

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You can make either pump work.

If you consider the idea that the new pump might be moved to a new well that has more capacity but nearly the same head, I would select the 5GS07 pump. It will provide plenty of head while the 7GS07 will be marginal for the deepest drawdown.

If the flow is too great at low heads (high level in the well) you can throttle the flow with a gate valve in your open tank setup. If the filter is on the supply to the tank, you would put the valve on the inlet side of the filter, and tighten the packing nut and take the handle off after it's adjusted so it is not inadvertantly closed. With the 5GS07 pump the valve will be set so there will be about 30 psi pressure loss across it when the flow is 7.5 GPM. At 5 GPM the pressure loss across the valve will be about 15 psi.

With the 7GS07 pump you would throttle the valve down to have about 50 psi pressure drop at 10 GPM.

As the water level goes down in the well the pump will operate along its curve at reduced flow and the pressure loss across the valve will become insignificant.

The pressure loss through the filter will vary from zero to about 30 psi, which is well within the range that the pump will handle.

You are trying to operate the pump to deliver a small average flow from the well, so throttling it when pumping into the tank is not a problem.

Excellent, that's the best news so far through this whole fiasco!

When we do drill it will be more shallow - more in line with neighbors who are at ~100' and getting between 8 and 20 GPM. But this set-up will stay intact for yard and horses.

We're not ready to do the storage system immediately but I imagine we will before winter. I think we've got all the information we need for now.

Thanx so much Bob for your thoughts and advice. You've been really helpful and we've learned so much. We'll keep you posted!
 
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