What do you often get when you ask, “How many gallons per minute do I need for my home”? The answer probably comes in specific numbers like 5, 6, 12 GPM, etc. But the same does not apply to different cases. Maybe, your home needs 10 GPM while theirs do not.
To put it simply, we have a thorough guide for you to follow. Now, it is time to get started.
How Many Gallons Per Minute Do I Need for My Home?
Normally, each person needs around 120 gallons of water daily. Based on this estimate, the flow rate should be approximately 12 gallons per minute. However, for an accurate calculation, we have to consider some elements. And here we go.
Water flow vs water pressure differentiation
GPM, standing for “the gallons per minute”, is a unit of measurement for both water flow and water pressure. Since the similarity is likely to confuse some people and lead to misunderstanding, we should put them into a simple explanation first.
The water flow represents the volume of water that flows into the household pipe system. And the water pressure is an indication of the force of that water flow.
Undoubtedly, water flow and water pressure come as two different things. But the former also can help to determine the latter due to a link between them.
Flow rate by household size and by square footage
We divide factors affecting the water flow rate into two categories. One relates the rate by household size, while the other is by square footage.
By household size
What is the household size?
It indicates how many people live in your house. For a standard household, there are normally from 2 to 4 people. And being above this level means a large one.
Unlikely, the larger your household size is, the weaker water flow you tend to get. The fact points out that the flow rate depends on the water usage. Having a higher flow rate will be impossible when many people in the house use water simultaneously.
By square footage
The second one is about the water flow rate by your home’s square footage. A standard household often measures around 2,000 sq. ft. setting with no more than 60 psi water pressure. Hence, above that rate, a diminishing water flow may drive you insane.
Formula for Calculation of Water Flow Rate
Determining the water flow rate requires some data. There are two common ways for determination, including I.D (inside measurement) and O.D (outside measurement). The larger diameter size of the pipe will offer a greater rate of water flow. However, a slower velocity can ensure better water purification.
The following is a group of three formulas needed to determine the water flow rate. (1)
Let us explain.
There are three things to bear in mind.
- Pipe diameter (inches): Inside measurement of the water pipe.
- Velocity (ft/sec): Speed at which water flows through the pipe into a container.
- Flow rate: Constant pace, a volume of water flowing through the container.
For better accuracy, we suggest taking these measurements around three times, then finding out the average of results.
In terms of GPM, it is 60 divided by seconds which it takes for a one-gallon container to get filled with water. For instance, if 5 seconds are how long to fill the container, its GPM will be 12 (60/5).
References
As a reference, one person often uses between 100 and 120 gallons of water per day. This range corresponds to a flow rate from 6 to 12 GPM as the best supply for numerous household devices as:
- A toilet: 2.2 – 5.0 GPM
- A shower: 2.5 – 5.0 GPM
- A bathtub: 4.0 – 8.0 GPM
- A faucet: 2.5 – 3.0 GPM
- A dishwasher: 2.0 – 3.0 GPM
- A washing machine: 4.0 – 5.0 GPM
In case you find it difficult to calculate the water flow rate accurately, we suggest based on these references.
How to test the water flow rate currently in use?
Many people need the flow rate calculation to build a new water system for their house while some others do not. If yours is currently in use, here is how to check whether it meets the demand well or not.
There are five steps in total.
- Step 1: Preparing a bucket in size from 1 to 2 liters and placing it under any faucet in your house
- Step 2: Setting up a stopwatch (it is often ready right in your phone).
- Step 3: Turning the faucet on.
- Step 4: Starting the stopwatch and turning the faucet off when it strikes 6 seconds.
- Step 5: Calculating the GPM by multiplying the liters (0.6 liters for example) in the bucket by 10 (0.6 x 10 = 6 liters per minute) and then converting it to gallons.
If the rate cannot reach 10 liters/minute, it represents the low one. From 10 to 15, it is acceptable but still needs improvement. And the flow greater than 15 will be the best measure.
How to improve the water flow?
One of the most important factors deciding a household water flow is the water supplying service.
In cities as well as suburban areas, water mainly comes from a public utility. But the case of the countryside does not hit the same when people there get water from wells or pumps.
Based on that fact, the following five points will help to improve the water flow.
Water Pressure
For households with the water source supplied by a water company, attaching the hose bib with a water pressure gauge is a good idea. The closer to the water source your device is, the more exact the determination will be. After screwing to tighten the gauge into the hose bib, it is time to turn on the faucet.
Normally, the typical water pressure a company can deliver is 60 lbs./sq. If the pressure displayed on the gauge drops, it means that your house water pressure is not consistent. As a solution, you should ask the water company for advice. When the water pressure becomes better, the water flow also improves.
Valves And Water Restrictors
Again, with the suburban houses, locating the valve box where water comes can also improve the flow rate. And, do not forget to open that valve by turning it counterclockwise.
When the device is a kind of lever valve, there is a note for you. The valve closes if it and the pipe make a perpendicular angle. Besides, in the state of partially closing, the valve causes the water pressure to be weaker. Thus, you had better check this valve as regularly as possible.
Another suggestion is that the water pressure should not be greater than 60 psi which can damage both plumbing lines. Furthermore, it is quite necessary to remove water restrictors inside the faucet to increase the water flow.
Showerheads And Faucets
The main purpose of checking all showerheads and faucets is to check whether there is any blockage. The likelihood points out that hard water tends to leave some Ca buildup inside showerheads or faucets. For months, this ugly stuff probably weakens the water flow into your container.
So, if the buildup stays, what is the solution?
The simplest way is to soak these things into vinegar/baking soda or wrap a bag of vinegar around them. It often takes hours for the buildup to dissolve. Assuming that the vinegar or baking soda does not work, replacing the old showerhead and faucets with the new one should be an alternative.
Piping
Do you choose the right types of pipes to get great water flow into your house? For the best result, we highly recommend devices made from polyvinyl chloride or copper. By contrast, the galvanized pipes are not a good idea since it easily gets deposited over time.
Pressure Switch
The final solution is to adjust the pressure switch. Firstly, you need to remove the switch cover and find its plastic nut after turning it off. Then, turn it clockwise with the purpose of increasing water pressure.
Note: the bottom pressure that you set must be 2 psi greater than the one on the pressure tank. To put it simply, if you set the bottom pressure at 50 psi, the pressure tank should stop at 48 psi.
Conclusion
So, how many gallons per minute do I need for my home? It can be 8, 10, or something else. For an accurate answer, our guide with the formulas above may help. We hope that the information we provide will be useful for your estimation.
If you have any questions, please let us know so that we will be back with further support. Thank you!