Residential dwellings with wells and pressure tanks are some of our most common pump sizing projects. We have a lot of experience here, and have seen anywhere from small 0.5 HP to quite large 3 HP pumps in a variety of households. Size is based on factors including the depth of your well, where you hit water, the production in Gallons per Minute (GPM) of your well, and the pressure any one individual prefers coming out of their household. Match that against the price you’re interested in paying, and the solution will always be a unique one.
If you’re specifically looking for a 1 HP pump, we have quite a variety, each with their own pump curves. To get a feel for the sizing process for a typical household, let’s run through some examples:
Example 1: Household A is replacing a 1 HP pump. They have a 300’ well with water at 150’. Their production is good at 2 GPM. They use about 500 gallons of water per day, and plumb directly from their well to a pressure tank.
In this example I’m going to assume a set max pressure into the pressure tank of 60 PSI. That is normally an overestimate to be safe, but if a customer tells me they’re looking for something else, I’ll change up that value. Using the value that 1 PSI of pressure is equivalent to 2.31’ of lift, I’ll be looking for a pump that can push about 140’, plus an extra 150’ to account for the Static Water Level (SWL) of the well. I don’t need to count the entire depth of the well because the production level is so high, so I wouldn’t expect the water level to drop at all. 500 gallons over a 16 hour waking schedule is about 0.5 GPM, as long as we stay above that value we should be good to go.
In this scenario I’d actually recommend a smaller 0.75 HP pump, our 05RPS07, that at 290’ of lift does about 5 GPM. 5 GPM is well over the minimum GPM required, so in general your pressure tank should always be filled. If the customer is still hoping for a 1HP pump, then our 10RPS10 at 10 GPM would be an excellent choice as well.
Example 2: Household B is replacing a 1 HP pump. They have a 400’ well with water at 50’. Their production is poor at 2 GPM. They also use about 500 gallons of water per day, and plumb directly to a pressure tank.
This example is a little trickier, because the well production is so poor. Setting the pump as deeply as possible is a priority, since whichever pump we have would most likely reduce the water level of the well as it pumps. If we set the pump at 380’ (20’ above the well bottom is standard practice) and add 60 PSI of pressure, we’re looking at a total lift of 520’. For 1HP pumps, the 05RPS10 is a feasible solution with about 3.5 GPM at that amount of lift. If the customer desired a higher GPM I would recommend the 07RPS15 instead.
Example 3: Household C has a new well and house, and are not interested in a pressure tank. Their well is 100’ deep, with water at 60’. Production is 20 GPM. They have a storage tank of 1500 gallons they want to make use of. They are also worried about freezing. They want us to assume all 1500 gallons get used per day.
This example has even more moving parts, but it has the potential for a really elegant solution. If there is a heated basement with the space then I would recommend placing the storage tank there. Otherwise the customer would need to bury the storage tank, with an additional underground platform for our 1HP EcoSteady Booster Pump. This pump has the ability to directly pressurize lines at the PSI you program for it (up to 55 PSI), so we highly recommend it if customers don’t have access to or don’t want a pressure tank. You would pair that pump with a smaller 18RPS05 well pump that matches the production of the well. Whenever a valve is opened at home, the EcoSteady Pump will sense that automatically and pump water at its’ set PSI. The well pump will need to be paired with a float to sense when the storage tank is no longer full; it would only run when the storage tank needs to be topped off.
As you can see, the well pump business is not a one-size-fits-all sort of affair. If you have questions or concerns about replacing a well pump or starting a new project from scratch, give us a call at (855)-560-5670 or email us at help@ruralpowersystems.com. We have friendly pre and post sales support, and we don’t make any commission so there’s never any pressure to buy on the spot. Let’s chat through your needs, and come to a solution that makes you confident in your own abilities to self-install!
