Answering Your Water Pump Questions
with RPS Engineer Mike
How Many GPM (Gallons Per Minute) Does a House Need?
How many gallons per minute (GPM) a house needs can vary quite a bit depending on how big the house is and what kind of water needs the house requires. A two bedroom one bath house with no garden is going to require a lot less than a house with three bathrooms and a large garden. It isn’t as easy as saying “you need 10 GPM for a house”, there are a few factors to take into account that will help you figure out what kind of flow rate will be best for your intended use.
The first thing to keep in mind is that an average tap, like what is in your kitchen sink, will have a flow rate of around 3 GPM max, and that an average shower will use 3-5 GPM. With that in mind, you can say that a house with one bathroom may only need around 5 GPM so that they don’t experience a drop in flow rate. With more bathrooms in a larger house, you will likely need a higher flow rate. Usually you would want to match a flow rate to be able to handle the highest water needs possible in your situation. So if you have a house with three showers, you may want to get a pump that will have a high enough flow rate that it could handle all three showers running at the same time (somewhere around 12-15 GPM).
If you have a garden or do any irrigation, this may need to be even higher depending on your water needs. If you run sprinklers, you can look up the type of sprinkler heads you have and get a GPM rating for each individual sprinkler head. Multiply that GPM rating by how many sprinkler heads you have and that would be the GPM you require to run your sprinkler system correctly. For example, if you have 10 sprinkler heads and each one requires 1.5 GPM, then you will need 12 GPM flow rate from your well pump in order to keep up. You can do the same calculations with drip lines based on the GPM rating of each emitter.
What if you have a well that has a slow refresh rate and only produces 5 GPM yet you have a house that requires more than that? The best option in that case would be to get a larger pressure tank or to pump into a storage tank with an on demand pressure pump. The storage tank will be able to hold a lot of water that is available to use at once, and your flow rate at that point will be determined by the pressure pump. Pressure pumps often have a good flow rate, and you can get one big enough that it will handle your home’s water requirements. And a larger pressure tank will mean that there is more water stored and ready to be pushed into the household, and if the pressure tank is big enough that your water needs are finished before the tank is empty, you won’t have to rely on the flow rate coming from the pump as often. A pressure tank can push water out quicker than it gets put in, but once the tank is empty the flow rate will be dependent on the well pump supplying it. A large pressure tank makes that less of an issue because it can push more water before it becomes reliant on the incoming flow rate alone.
If you still have any questions at all, you can always give us a call and talk to one of our pump specialists who can help you find that right pump for your specific needs. Call us at 855-560-5670.
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