Well flow test / well quantity or recovery rate test FAQs.

This article series describes how a home owner or home buyer can test, measure, or estimate the amount of water available from a well and how to evaluate the water pressure delivered in a building served by a private well.

Q&A on How to Do Your Own Well Flow Rate/Well Yield or Drawdown Test

These questions & answers about well yield testing or flow tests were posted originally at WELL FLOW TEST for WATER QUANTITY - be sure to see the procedures and advice given there.

The sketches shown here were provided courtesy of Carson Dunlop Associates.

On 2018-03-28 by (mod) - well pump protection for low flow wells

Scott a tailpiece in the well or a pump protection switch protect a well pump from being damaged when well flow rate is poor.

See WATER PUMP PROTECTION SWITCH

On 2018-03-28 by Scott Osman

I recently replaced a submersible well pump with a 10 GPM pump. What if my well isn't flowing 10 GPM? Does the pump match itself to well recovery or is it running away from my water? Thanks

On 2017-09-12 by (mod) -

Yes, but you would need a generator or an energy or power source to keep the pump running during the test.. That could be as long as 24 hours depending on the test specifications.

On 2017-09-12 by lemuseduardo3@gmail.com

Can a well flow test be done on a piece of property that has no power?

On 2017-02-07 by Claudia

The well at our home in Beaufort SC hits the Florida aquifer at 182 ft and is drilled to that depth.

The casing only goes down 92 ft. We are getting sand and/or silt in the water all the time for several years. We put in a filtration system to take the silt out as it enters our home.

The first of three filters shows an unusual amount of silt coming in. One expert told me that the casing should go all the way down to the same level as when it hits water. Is this true?

On 2016-05-10 by (mod) - home inspection dilemma about refusing to let a well be tested

Lisa

If a home seller will not permit a well water flow test or quantity test you should be very worried. There are in my experience only two explanations for such a position:

1. The seller knows that there is a well water problem or has had a history of running out of water or burning up well pumps, so she is telling you ahead of time that the well capacity is limited and that depending on the situation and your needs you could be facing a significant cost to get enough water supply.

2. There may be no actual problem but rather someone has told the seller to avoid letting your inspector test something because the "someone" has elsewhere run into these problems and hopes to avoid disclosing it at the seller's home.

However a well flow test needs to be performed properly. I'm not sure what "full blast" means. Nor do I consider 2-4 of running water a valid well flow test. Some water pumps are capable of delivering a very high water flow rate. If the volume of water your "test" is taking out of the well exceeds daily water usage norms in total volume or in time, then it's a bit of an extreme test that could also be questioned.

A properly constructed well flow test is done over 24 hours and measures the actual flow capacity of the well; it usually requires a calibrated, adjustable-flow-rate pump used by the well driller at the time of well construction: that's not something you're going to accomplish at a home inspection.

Other "tests" of water flow, such as running 3-5 gpm for some time period, are not a complete, valid test, but they are reasonable indicators that the well appears to be reasonably functional.

That is, unless the well has a very large static head, if the well flow rate is really inadequate, that usually shows up during the 2-3 hours of a home inspection or a septic loading and dye test.

On 2016-05-09 by Lisa Lewis

If the seller of a home insists that we do not run a quantity test on their home, which i'd like to purchase, how much should I worry?

She claims she is worried about the inspector burnig out her mototr if the water is run full blast for 2-4 hours.

On 2015-12-12 by (mod) - true pump delivery rate varies by lift height

Sorry I don't understand the question. IN general a 50 GPM pump can pump a maximum rate of 50 GPM - by definition.

The pump's actual pumping rate will be less depending on the number of meters of lift it has to overcome.

On 2015-12-12 y dvakar

how much a 50gpm pump pumps out n a submersible pump in a mines well, whether it will take 50 gpm or more

On 2015-10-17 by CJ

Thanks. Is it normal to have such a variance in recovery. My well is 32 feet deep(29 feet under ground) and has two capped well tiles for a reservoirs at the bottom of the well

The water level gets up to 24 feet level when the well is not pumped. The recovery seems better when the water is high 3/4 to 1 tile in a 24 hr period and I don't pump it down as far.

When I pump it below 3 tiles, it takes longer to pump the water out of the well(I'm guessing that's my static level), but the recovery is slower 1/4 tile to 1/2 tile in 24 hrs,

I'm assuming this is because it has to fill up the gravel and the tile in the lower section of the well? I have not built yet, I'm very nervous I won't have enough water, any insight would be greatly appreciated.

On 2015-09-12 by (mod) - What is the minimum recovery I can live with

CJ

Please see the typical family water usage data at

WATER USAGE REQUIREMENTS

You can live with a horrible well recovery rate if you can store enough water on site and then simply refill the tanks slowly during off usage hours.

On 2015-09-12 by Cj

I have a dug well that's recovery varies from 1/4 tile to 2 tiles in a 24 hour period. What is the minimum recovery I can live with for a family of 3.

Well tiles are 4 feet by 4 feet. Thanks for any help

On 2015-08-22 by (mod) -

Good questions to pose, Chuck and good details for a property owner to have at hand.

On 2015-08-21 by Anonymous

Shanon:
Just a few questions so I have an idea about you well

Do you have a copy of your well log? If you don't the driller should have a copy.

What size pump is in the well and what depth is the pump set at?

What is the pressure when the pump is running?

Was a well drawdown test done?
Chuck

On 2015-07-26 18:42:00.343806 by Shanon Crumbley

I have been assuming the well was running dry, but now I'm not sure.

We bought this place that had a well and pump in the ground and have got electricity and put a pressure tank in. The well pump kept kicking on and off so we called the man who drilled the well back in 1985. He came and had to pull the pump and put a check valve in.

Since then when watering I would run out of water and then wait 20 min or so and it would be back on.

Over time I realized that it was not taking the same amount of time to run out of water or for the water to be restored. It's almost like the pump doesn't start replenishing the system till the water is all the way gone. Say I'm watering and the pressure is slowing so I think it's about to shut off so I turn it off.

15 min later I turn it on somewhere else and it runs 2 mins and is out of water but in 2 more minutes it has water again. What could cause this type of scenario. When the well was drilled the flow rate is recorded as 7-10 gpm

On 2015-07-24 by (mod) - There is no average residential well flow rate that is location or area independent

Ric

There is no average residential well flow rate that is location or area independent, but 20 gpm is a good flow rate, about 4x the minimum that a lender would typically want to see.

On 2015-07-24 by Ric

What is the average gallons per minute from a well. Is 20 gpm sufficient?

Comments:

(June 11, 2011) M.Akram said:

Very Informative

(Mar 7, 2012) bryan said:

ask thr neighbors about the well and any problems they might have had with their well or if the previous owner had anny well problems. a;ways talk to the neighbord before buying and also the health department and a well drilling company tht may have worked that neighborhood.

(Jan 27, 2013) Dan said:

I have been doing the well flow..with a hose and, flow guage for 17 years and, never got a call back that the well went dry or, the test was not accurate so..the hose with the flow meter test works...period

Reply:

Dan's hose and flow meter are of course not measuring well capacity nor flow rate, just a quantity delivered over his test interval, confounded by pumping rate and other variables. Useful but not a true well flow test.

Question:

why is my well water killign the leaves on my plants?

Reply:

Anon, I don't see a question from you here. And I have no reason to think that potable well water kills leaves on plants. If you suspect your well water you should have it tested by a certified lab. For that matter private well water ought to be tested annually in any case.

Or you may be over-watering your plants, drowning them.

Question: well test costs

(Apr 4, 2014) lorraine said:

Any one knows what a quantity test for a well will cost in rural WA?

Reply:

Well flow tests do vary widely by area and I don't have a figure for rural WA, but typically you can figure as much as $1200 or more for a true flow test.

Beware that short-cut tests may not be useful. To actually know a well's performance the contractor has to use a calibrated flow-rate pump at the well and pump for a specified time interval, possibly 24 hours, in order to be able to actually know the well's capacity.

If someone is charging you $50. and just stopping by to run water for five minutes, that might be measuring the flow rate of your pump and plumbing system by not the well capacity.

Question: well water problems in Spain Espana

(Apr 27, 2014) Jamas said:

Hello,

I am a farmer from Spain. I will try to explain my problem, but sorry for my bad english.

I have a well for 2 years now, 7 meter, and with 2 meters of water. Last month i decided to digg more on this well, because i need more water for the plants and trees.

After 3 meters, i found hard rocky ground (stones). after 6 meters, under the rocks i found now black sand.

total meters: 10 + 6 meters of rock = 16 meters. And still not more water found.

Do i have to digg more, or do you think there is no more water. How can i explain this black sand? is this a sign for water or not?

any advice will be appreciated.

Reply:

Jamas,

Gracias por la pregunta y explico que mi espan~ol no es perfecto tambien. No se si la arena negra significa que vas econtrar agua o no, pero es common que agua corre por arena por eso es posible.

Pero tambien hay peligro cavando muy profondo en un pozo por mano si no usas seguridad de una pared de cemento o piedra.

De que diametro esta el pozo. ?Si es ancho, sea posible cavar una cavacion mas fondo pero no ancho simplemente para buscar el agua?

Por favor, nunca trabajas solo.

Saludos

Daniel

Question:

(May 9, 2014) sylvie said:

Hi,

I forgot to turn off the faucet outside it ran for at least 4 hours. Now i have gray water everywhere when I turn the water on. Is it possible to empty a well because of it? Will it fill back up? How long will it take?

Reply:

Yes you may have run water so low in the well that you began picking up silt. Most wells will recover in anywhere from a few hours to overnight. If the silt problem continues you may need to flush the water tank and piping.

Question:

(May 22, 2014) Meme said:

My well pump goes on and off both approximately every 7 - 9 seconds. Is this ok? When faucets are open outside the pressure of the water increases and decreases according to the pump going on and off.

Reply:

No Meme

short cycling will burn up the pump

see

inspectapedia.com/water/Short_Cycling_Pump.php

Question:

(July 28, 2014) Melanie said:

My pressure tank will drop pressure every 60 seconds with out the water being on. I have looked all over the house for leaks and cannot figure out why it looses pressure on it's own. because of this it is about to wear the relay out. Any suggestions?

Reply:

Melanie

A good diagnostic for the pump cycling you describe is at

WATER PUMP INTERMITTENT CYCLING

Let us know if questions remain after you've seen that article.

Question: home seller does not want to permit a well flow test

9 Oct 2014 patti said:

My clients do not want a well inspection test done this time of year (Oct. in North Idaho) as the buyers have requested. My clients said when they do well tests and pump they run the well dry. Is that true?

Reply:

Patti.

A properly-conducted well test, if you're talking about a true flow test, might indeed "run the well dry" in which case the test has discovered a limit on the well's ability to deliver water.

What is very important is that the test person be on-site, paying attention. If the water supply stops, one must TURN OFF THE PUMP IMMEDIATELY to avoid possibly costly damage to the pump or its controls. Following that shut down one might also observe the necessary recovery time until water is again available, as that gives more interesting data about the well.

A sanity check on the procedure followed by the tester will include noticing just how much water the well delivered, over how much time. I'd want to know that data to protect against someone constructing a test that was unreasonable and thus did not give an accurate idea of the well's normal, in-use performance.

You've already been put on notice by their reluctance to permit a well test that this seller's well is probably of limited capacity - probably - else they'd not be worried about having a test performed. My OPINION (I'm not an attorney) is that this situation is just begging for a later dispute about fair and proper disclosure.

If I were selling this property I might however also be worried about some idiot flooding a septic system drainfield by running abnormal water levels into the wastewater system.

If I were buying this property and the sellers would not let me perform a normally-conducted property inspection or test I would have no choice but to assume that that component was not functional, and to consider that in deciding what I'd pay for the property.

However, in my opinion, it's rarely the case that a defect or repair should be a basis to abandon the purchase of a property: most repairs are a very small percentage of the total property value.

Even needing to improve a well's yield or drill a new wall, which could certainly be several thousand dollars or more, should fall in that category.

Finally (well it's never really final, is it?)

the "well test" performed by many amateurs and some "pros" is not a true well flow test - which is done by well drillers and requires a special variable-rate pump, at the well, running for 24 hours to measure flow rates over that period. More often an inspector just runs some volume of water over some interval, or combines a flow test with a septic loading and dye test.

Those tests are not complete, do not give a true well flow rate, and are confounded by pump rates and other variables. But those tests CAN detect a well that runs out of water after delivering only a comparably small volume of water.

...

Continue reading at WELL FLOW TEST for WATER QUANTITY or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

Recommended Articles

• WATER PUMP DRAWDOWN VOLUME & TIME
• WELL FLOW RATE
  • WELL DYNAMIC HEAD & STATIC HEAD DEFINITION
  • TOTAL DYNAMIC HEAD
  • WELL YIELD, SAFE LIMITS
  • WELL YIELD DEFINITION
  • WELL YIELD IMPROVEMENT
• WELL FLOW TEST for WATER QUANTITY
• WELL LIFE EXPECTANCY

Suggested citation for this web page

WELL FLOW TEST PROCEDURE FAQs at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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INDEX to RELATED ARTICLES: ARTICLE INDEX to WATER SUPPLY, PUMPS TANKS WELLS

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