Shopping Cart

Your cart is currently empty.

How To Test Your Well Water Flow Rate

well water flow rate

Welcome back to Clean Water Made Easy Podcast!  On this weeks episode, I talk all about well water flow rate and how easy it is for you to find out what the water flow rate is yourself.

Today’s episode may be brief, but it covers a necessary topic. Enjoy!



  • Why knowing your flow rate is important
  • Figuring out how many gallons flow from your pump in one minute
  • Important numbers to know
  • The process of checking your flow rate



Hello, welcome back! Thanks for tuning in to the Clean Water Made Easy Podcast. My name is Gerry Bulfin. I’m a water treatment contractor and WQA certified Master Water Specialist. In this podcast series, I give out easy to follow tips and information all about well water, well water treatment systems, and how to improve quality of your well water.

Importance of knowing your well water flow rate

In this episode we will cover the simple steps you’re going to take to find out the flow rate of your well pump. What’s the importance of this?, you might wonder. Why should I find out what my well water flow rate is? Well, flow rate is how many gallons per minute your well pump can put out. It’s important and nice to know what your well pump flow rate is and how many gallons per minute it can put out and then check it again a year from now. It just takes minutes to do so it’s easy to find out. It’s good to know if there’s any changes.

Why is it important to know your well water flow rate

One of the most important reasons is those for sizing. Sizing your filters, sizing your home, add bathrooms to your home, you want to know how many gallons per minute you have available from your well pump, you might want to, if it’s possible, change the pump size to get more flow rate is not always possible but there are some wells where this is possible. Or you need water treatment so a lot of folks come to us, they want to size a filter system but first you need to know how many gallons per minute your well pump can put out, we can figure out what size of filter system works for you.

Also a lot of folks want to know the well pump flow rate if they’re troubleshooting water pressure or low flow rate situation. I made a companion guide … to check your flow rate and also some pictures to and along with different information along with a simple calculator that will allow you to plugin and the 2 numbers that you need to quickly find out the flow rate. If you to get your free copy just text the word flow rate, one word to 44222 or go to and we’ll get that going to you free of charge.

What is flow rate?

So again, what is flow rate? Flow rate is simply defined as how many gallons in one minute your well pump can pump from your well. Now this is determined generally by the size of your well pump. So larger pumps will pump more gallons per minute, smaller pumps less, also how deep your well is, the pressure you have your pump is set at. But for these purposes, what we’re talking about is how many gallons can flow in 1 minute from the well into your pressure tank. That will give you an idea of what your well flow rate is.

So for instance, if you can fill a 5-gallon bucket in 60 seconds then you can consider you have 5 gallons per minute coming from your well pump. If you could fill that same 5-gallon bucket in 30 seconds then you could say you have 10 gallons a minute. You may have a submersible pump that has a variable speed and a pressure that is constant pressure system. Meaning that maintains a single fixed pressure in.

Measuring flow rate

What we’re talking about in this episode is measuring the flow rate from a standard single speed well pump, not constant pressure systems. Most folks have this type and you can generally tell if you have that kind, you have usually a blue tank, of course different colors, but blue common color, and you have a pressure switch, and you have a pressure gauge.

The pressure turns on at 1psi and off at another. So for instance, say you run the water and you notice when you clicked that your well pump is turned on at 30psi and then it turns off at 50psi or it might turn on at 40 or off at 60 but usually there’s a 20 psi differential where it turns on at the cut in, the lower pressure and cut out at the higher pressure. If you have that type, which most folks have. then you can easily figure out what the well water flow rate is.

How to measure  flow rate

If you have a constant pressure system, usually they maintain a single fixed pressure and a pressure tank usually a 5-gallon bucket and .. it’ll say, if you have any doubt you can talk to your contractor or well driller it can tell you what kind you got; they’ll also tell you what your flow rate is as well often they have the record, but oftentimes they might use a different test pump recommend folks, they also protect tell you what your or you need to look at the literature and find out based on the psi it will tell you how many gallons it’ll produce.

Okay, so basically there are only 2 numbers that we need—just need to know what the drawdown is coming out of your pressure tank. All these is your pressure tank fills up with water when the well pump pumps it up the pressure switch shuts it off then you got a pressure tank that is full of water and it might have 5,10, 20, some have 20, 25, gallons of water in a larger size.

Anyway they have a certain amount of water in them that, if you run the water say in a hose bib or a faucet and you’re getting water out of the pressure tank first and then once you draw the water out of the pressure tank, the pressure will drop and the pressure switch will turn on the well pump so that’s considered the drawdown.

Like I said the common drawdown is somewhere between 10 and 20 gallons depends on the size of your pressure tank more or less. So that’s the first thing we need to find out — is how many gallons of drawdown do you have. And the other number we need is, how many times in seconds does it take your well pump to turn on and the pressure tank to turn off. This is referred to as the cut-in, cut-off cycle of the well pump.

So that’s it, you just need to know 2 numbers – the amount of water in gallons for the draw down, the time in seconds it takes for the well pump to fill up pressure tank, more or less. So it’s pretty straightforward. First what you want to do is to allow the well pump to build up, all you have to do is pressure first run the water in the home until you hear the pressure switch points…clicked, then you hear your well pump turn on.

Some folks will say pretty silent they just cant hear anything. It’s pretty rare you cant help it especially if your system is a little older. Easily get to it, but if you can go near the pressure tank, pressure switch… You can hear the, not exactly the well pump itself, which is submerged in water they’re working down, but you can hear the pipes kinda move when the water starts to flow the idea is we want to start with a full pressure tank.

So you run the water in the house, let the pump build up the pressure, shut the water off, your well pump is built up to pressure and then there’s nobody else using the water in the house. The next thing you want to do is get a bucket, I use 5 gallon bucket but you can use any size bucket as long as you know how many gallons it is.

Then measure the water out of that pressure tank. Use a hose bib near at or one you say doesn’t really matter. The idea is you’re going to measure how many gallons is coming out of that pressure tank until you hear the well pump turn back on. So you run some water in the 5-gallon bucket then, run some more into the 5-gallon bucket, finally in our example here, we’re going to say it’s 20 gallons. So you get 20 gallons .

So you filled up that 5- gallon bucket 4 times, now you have 20 gallons and also you hear the pressure switch point close and the pump is turning on and flowing because the pressure dropped down. So now we know we have 20 gallons of draw down. Next, we just want to time the period it takes for the well pump to build back up to pressure.

That is between the cut in and cut out of pressure switch. What we do there is run the water make sure no one else is using the water, run the water until the pump turns on. Then you turn off the water. Then time it in seconds. How many seconds it takes to build back up the pressure tank shut off. So now we have the 2 numbers, the drawdown in gallons, we say it’s 20 and I’m going to say it’s 120 seconds to build the pressure back up.

So for instance, you have say 20 gallons drawdown and it takes 120 seconds to pressure back up. I’m going to take 20 and divide that by 120. The calculator came out to .166. Now just take that number .166 multiplied by 60 which is the number of seconds per minute. These are gallons per minute comes out to 10. It’s pretty common for eventual applications.

There you have it. We have 10 gallons per minute flow rate. So this is all in the guide How to Find Out Your Well Water Flow Rate mini ebook and you get that for free. Just text the word flowrate to 44222 or go to the website and you can find it there. Okay. This was a short but important episode. The next episode, we’re going to delve into How to Test your Well Water, what to test for, and difference between do it yourself (DIY) and Certified Lab Test with together versus test-it-yourself. That’s it, looking forward to talking again.

If you find the information here helpful, please share it with your friends.

[bctt tweet=”“It is important to test your well water flow rate and it is easy to do as well!” -Gerry Bulfin” username=”@gerrybulfin”]

Share Button
  • Clean Water Systems & Stores, Inc., Water Treatment Equipment,Service & Supplies, Santa Cruz, CA

Visa, Discover, MasterCard, American Express, & PayPal

Font Resize