Which Pump Should I Put in my Deep Well?

One of the most common questions we get is, “which pump do I need for my well?” If you need a quick and simple answer, then this is the guide for you.

Note: This guide is specific for Hallmark Industries pumps, which we use the most often in our installations.

It will be tempting to use your old pump’s horsepower and just go with that, but there is no guarantee that will work. Every company will have different hp ratings for their pumps, so it’s always safer to go through this guide and make sure.

A few quick numbers you will need before we get started:

• Your pressure tank switch settings (if you have one). These typically come in three settings: 20/40, 30/50, and 40/60.
• Your well’s depth to water (or head). This is the distance from the top of the water to the top of the well. If you don’t have your well’s depth to water information, check out our handy guide here to measure it yourself.
• The power source you have available for your pump, 110v or 220v.
• Your well casing diameter. The smallest well casing these pumps will fit is a 4 inch well casing.

Once you have that information, simply take your well head number and match it to the pump on the table. We advise against getting a pump that is too powerful for your application, as it may cause additional stress to your system.

If you have a pressure tank, you will have to do an additional calculation. Take the higher pressure number, multiply it by 2.307, and add it to your well head. This will be your well head number that you match to the table.

Let’s try an example. Say I have a well that has a head of 100ft, and my pressure switch is 30/50. I would multiply 50 by 2.307 and add it to 100. So (50 * 2.307) + 100 = 215.35. Since the 1HP pump can only handle 207ft, I would go to the next one up and choose the 2HP pump.

Tip: If your well head is just above the previous threshold, consider sizing down your pressure switch. In the previous example, if I switched from a 30/50 to a 20/40 switch, I could use the 1HP pump and save some money.

And that’s it! If you still need help or have an unusual application, give the manufacturer a call here. Good luck!