Whole House Water Filter Pressure Drop (Updated 2023)

One of the most common concerns people have when they are considering installing a whole-house water filter is whether or not it causes a drop in water pressure. This concern is because any filter will restrict water flow to some degree.

There are a number of factors in any home that can contribute to a change in your home’s water pressure and whether it’s too low. Read on to learn what the optimal water pressure is and how to increase it after installing a filter.

What Is Flow Rate & Water Pressure

There are two critical factors at play when it comes to the strength of the water coming out of your faucets, and these are flow rate and water pressure. Though these two factors are related and often confused, they are by no means the same.

The flow rate refers to the amount of water that moves through your home’s pipes. In contrast, water pressure refers to the force exerted on the water in order to move it, which is, in turn, exerted back on your home’s plumbing.

These two factors have a strong relationship because the higher the pressure, the faster water will move through your pipes. Similarly, the larger the diameter of the pipes, the less pressure will be needed to move water through your home. All things equal, the greater the pressure and size of your home’s pipes, the greater the water flow.

Calculating Your Water Pressure And Flow Rate

If you are using a city water supply, then you can figure out what your home’s water pressure is by requesting a reading from the municipal supplier. When the pressure is too low, then the company itself may be responsible for solving it.

If you are on well water or just want to do it on your own, you can also use a water pressure gauge. To do this, simply shut off all the faucets in your home and attach a gauge to an outdoor faucet. Next, turn the faucet with the gauge attached and observe the reading.

The gallons per minute flow rate in your home can be calculated by tracking the amount of time it takes to fill up a container of water. Take a 5-gallon bucket and place it beneath your faucet. Turn the faucet completely open and measure the time it takes to fill the bucket with a stopwatch. When the bucket is filled turn off the faucet and stop the timer.

To calculate GPM use the following equation: 60 ÷ seconds to fill x number of gallons filled = GPM

Factors That Affect Water Pressure

In most cases, water pressure is measured in pounds per square inch (psi). In a typical household, water pressure is between 40 and 60 psi, which is suitable for providing a healthy flow of water without risking damage to pipes. There are several factors that come into play in either increasing or decreasing water pressure. Here are some of the most significant.

Water Source

No matter how powerful the water pressure is at the source, either the utility or well pump, its location relative to your home will play a large role in how powerful it is by the time it reaches your faucet. For every foot of the pipeline between your home and the source, friction will result in a significant loss in pressure and flow.

Additionally, every curve or fitting causes a loss of energy which reduces pressure by the time it reaches your home. Keep in mind that not every utility or well pump will create the same pressure to start with, either.

Size Of Pipes

The size of the pipes in your home will determine the amount of water that can flow through them. If these pipes are too small relative to the demand in your home, this will lead to a significant loss of pressure when multiple outlets are running. The same applies if clogs or a buildup of scale results in a lower effective diameter.

Time Of Day

Many people aren’t aware, but the time of day can have a significant impact on water pressure. This is because, during peak hours of usage, more people are drawing on the water supply. Likewise, water pressure will drop during summer and spring when water is used more heavily. 

Do Whole House Water Filters Reduce Water Pressure?

When regularly maintained and installed correctly, a whole house water filter should not cause a meaningful reduction in your home’s water pressure.

A whole house water filter does create a restriction in order to clean the water coming into your home, but in most cases, this is limited to only two to three psi which won’t be noticeable under most circumstances. However, there are some conditions under which a whole house filter can cause a loss of water pressure. This includes the following:

• The system is undersized for the home;
• The plumbing connection uses too small a diameter;
• The filter ports are too small;
• If the filter is low quality; or
• If the filter elements have become clogged.

Additionally, a whole house water filter can reduce water pressure if they are not properly maintained. The best way to avoid this is to follow a regular filter replacement schedule so any problems are caught early and don’t lead to costly repairs.

If you have a correctly sized, high-quality system that is in good working order, it shouldn’t cause problems with water pressure. It is important to understand the filter’s specifications to ensure the system you have is correctly sized for your home.

What’s a Good Flow Rate for a Whole House Water Filter?

The optimal flow rate for a whole house water system can be anywhere between 5 to 20 gallons per minute (GPM). This is a wide range, but that is because the particular flow rate depends on the size and number of residents in your specific home.

Here is a more specific breakdown based on the number of residents in a two-bathroom home to help you understand the optimal flow rate for your home.

• Houses with 1-2 residents should use systems offering a flow rate of 5-10 GPM.
• Houses with 2-3 residents should use systems offering a 7-12 GPM flow rate.
• Houses with 3-4 residents should use systems offering a 10-14 GPM flow rate.
• Houses with 4-5 residents should use systems offering a 12-20 GPM flow rate.

In addition to residents, the number of bathrooms and appliances can have a significant effect on the demand for water. In general, higher demand means a greater flow rate is required.

How To Increase Your Water Pressure

Chances are if you’re dealing with poor water pressure, a whole-house water filter is not the cause of the issue. Many other factors play a role in water pressure which is more likely to cause a weak water supply.

If you have low water pressure after installing a water filter, take these steps to help solve the problem:

Clean Or Replace Sediment Filter

A whole house water filter may be accompanied by a sediment filter that captures debris in the water before it enters the system. Depending on the micron rating of the filter, it can become clogged, which will restrict water flow and reduce water pressure. Like all water filters, these need to be replaced or cleaned regularly to ensure high pressure.

Check Your Shut-Off Valves

Your first step to solving your low water pressure should be to ensure all of your valves are completely opened. You can start with your main shut-off valve, which often is located in a basement or crawlspace. Next, look for the main feed valve, which is typically located close to the meter.

Unclog Constricted Pipes 

For homes with hard water, which is most of them, it is possible that your pipes have built up deposits of limescale from the minerals in your water. This can create constriction reducing flow and pressure. A water softening system can prevent this issue, and in time the soft water may dissolve some of the buildups. However, in severe cases, the affected pipes may need to be replaced.

Install A Pressure Booster

In cases where the water pressure in your home is low due to factors you cannot solve, such as a weak municipal supply, adding a booster pump may solve the issue. A booster pump can be installed to increase pressure on your whole home. Doing this will allow the filter to operate more effectively at the appropriate PSI ratings.