Making My Backroom More Functional

Figuring Out How Much Water You Should Use Before Choosing a Submersible or Jet Well Pump

by Phil Lawrence

Before choosing a submersible or jet well pump, you will need to have a good idea of your overall water needs. Start with the approximate gallons per minute (GPM) you will need the pump to handle. This will help to narrow down your pump choice considerably.

Estimating Your Needed Gallons per Minute or Hour

Submersible and jet well-pump sizes are usually rated by how many gallons they can pump per minute. The pump size you require should coincide with your peak amount of water usage. There are several ways to figure out the approximate GPM, and here are a few of them.

Add up the people—The USGS estimates that each person uses up to 100 gallons of water per day through doing things like taking showers, washing their hands, flushing toilets, and so forth. All of these things contribute to that number.

What you can do is add up the number of people that will be in the building on any given day. Multiply that number by 100. You can divide that result by the hours in the day or by how long the building will contain people each day. The result is your GPH rate. If you divide that further by 60, you will have your needed GPM rate.

Add up your water fixtures—If you add up every source of water in and around the building, you can figure out a rough GPM figure. Most faucets have a 1 GPM minimum and around a 2.5 GPM maximum draw.

Add up every faucet, hose, spigot, and appliance that uses water. That will give you a general GPM to work with. Sometimes, the fixture itself will have its GPM rating stamped into the metal.

Do the math—Getting a specific number can become complicated. You can get close to one yourself with a calculator. However, for very specific GPM numbers, you should really speak with a professional pump seller or contractor.

Remember that you're looking for peak demand. Your building won't operate at peak demand at all times. You want a well pump that can easily handle daily usage without that usage putting any strain on the pumping mechanisms.

What Happens After You Know Your GPM

Knowing your needed GPM will help you narrow your choices down to the pumps that will serve you best. Your well depth can help you choose between jet and submersible options. Your budget will help you make the final decision from there. Choosing to purchase your pump from a reputable dealer will take you the rest of the way.