GPM from pump, or is it from tank?

I have to fill out a useless but required real estate form that asks what is the "Gallons per minute capacity of your well pump" How can I get this accurate? If I do the "fill the 5 gal bucket" method, it will only measure how fast my tank can push water out since it has a 5.9 gal output.

Pump is 1/2 HP Goulds submersible at 200 ft, with a Well X Trol 202 tank. If I do the test at the low pressure end of the tank (30-50 switch), the pump will kick on during the test. Will that give me different results (shorter time to fill).

thanks,

Open a hose faucet and let it run. After the pump starts, let it run until the pressure stabilizes, presumably below shutoff pressure.

Measure the flow rate with a bucket and watch. That is the capacity of the well and pump AT THAT PRESSURE. It will pump more at lower pressure.

Unless you run the well out of water you are measuring the capacity of the pump; not the capacity of the well.

Bob, When I let a hose run I can see the pressure slowly fall, then rise when the pump kicks in, then slowly fall. It seems that the hose cannot drain the system as fast as the pump pressurizes the tank, so it hits the shutoff. Does this matter for my GPM tests? It seems that I am still getting pressure only from the tank for part of my bucket filling.

For reference, I fill my 5 gal bucket in 56 seconds.

Pick a number, any number. Make it above 4 GPM since that is the FHA/VA loan threshold, if you say 10 GPM, and they measure it and it's 8 GPM, it was because the pump is slowly wearing out....

i.e. make it up.

Rancher

I would first check the condition of your tank.It sounds like there isn't much air in it if the pressure is fluctuating like that.It also could be under sized.Check the air pressure by shutting the power to the pump and draining the water out of it.Your should have a minimum cycle of 30/50. Whatever pressure setting its at make sure the air pressure in the tank is 2lbs. below the turn on pressure of the pump. I would also run a hose straight off the tank and test the GPM from there. That is where you will get your most accurate gpm aside from running the water at the well.

SAM

OK. I will probably make up a nice believable number like 7.5 since they are not going to measure it, and there are no problems with the system. My test was done at the end of a long garden hose anyway and I might get over 7GPM anyway if I tested at the tank.

thanks,

Your line from the pump is usually the largest diameter, it then reduces going to the faucet you are connecting the hose to and then the hose diameter, usually 1/2" hose.

You can't get enough water out the pipe ID to the faucet, thru the faucet and then thru the hose to be able to control the pressure with the shut off valve to the average 40 psi for a 30/50 psi system. Which is how you normally are supposed to do this (with a flow meter on open discharge out of the meter). So you measure many gallons less than actual and see/suffer the pressure fluctuation which confuses things more.

In many cases the model number of the pump gives you a coded gpm of the pump. I.E. Gould's 5GS05*** is a 5 gpm 1/2 hp; 13GS15*** is 13 gpm 1.5 hp.

And that is what they actually asked for; "the gpm capacity of the pump". That isn't what they really want, they want to know how many gpm the house has to use so they might determine the peak demand gpm the house might have for use but... that then depends on the water level in the well at the time of the test and that can vary widely with recent and longer past precipitation levels.

They are attempting to 'test the well water system' without taking the well into account due to not wanting the expense of a well pump test that can take long hours to a couple days and costs hundreds of bucks at least. I suggest it is a liability CYA thing for the agency and agent. In today's "It's not MY fault' society, I'd be careful with the number I put down because the new owner may be able to come back on you when they want to add a sexy 6 body spray two person foot long showerhead each shower next year and find a trickle of water is all they get out of it after maybe ten grand to put it in.

In this area of the USA, you would be asked first what is WELL gpm production, for which you would [should] get from the well driller for about 250$ Unless he pulled your pump and used his test pump, that number is limited to the pumps capacity. The test is pressure irrelevant, so you could open a 1" line and let the pump run full bore to get the GPM figure.

I agree that it is safe to estimate low. Here, 2 GPM is adequate for approval.

Doctors that give you 3 months to live never get sued when you get 12 instead.

your GPM flow would be 5.35 based on the fact it took 56 seconds to fill your 5 gallon bucket:
(gallons / seconds x 60) = GPM

5gal / 56 x 60 = 5.35

Also I had the same problem with my pump fluctuating up and down. The well pump would only run for about 5 seconds then shut off... The pressure switch would hit 60 pounds, then shut off... it would be off for about 10 seconds and then kick on again. It was really causing my pump to work overly hard to keep up.

The problem was my pressure tank had gone bad. The bladder inside the tank was leaking air and no longer held enough pressure to let the system work properly. The pressure tank was replaced, and my water flow went back to normal. Now my pump will kick on and run for at least 30 seconds before shutting off... You should probably look into replacing your pressure tank. Hope this helps.

look up the pump spec. sheet, and see what the manufacture says, because going through the tank and the piping and hydrant you will not be able to get an accurate measurement of the well it self.

Even without measuring the bladder pressure in the tank, I believe that it is OK. When I water a new section of lawn, by hand with a hose I can see the pressure SLOWLY go down. This takes several minutes. Then when the low pressure limit hits, (30#) I can see the pressure build up to the Max. This takes about 30 seconds. All the while the hose is going pretty much full bore. Tank drawdown is 5.9 gal. Pressure in the house seems quite normal.

By the way, how often should I check the pressure in the bladder tank (Well-X-Trol 202)?