Does a Whole House Water Filter Reduce Water Pressure?

You know your water quality is bad, and you hate drinking and showering in your water supply in its current state. But you still appreciate that you have instant access to water when you turn on your tap, and your shower water might be contaminated, but at least there’s plenty of it.

If you’re toying with the idea of getting a whole house water filter, but you’re scared about what it might do to your water pressure, you’re not alone. Water filters are a tempting investment – but only if you can be sure that they won’t cause water to trickle out of your faucets.

TL;DR: Do whole house water filters greatly affect water pressure?

We’ve tested tens of whole house water filters in our decade in the water treatment industry, so we can confidently say that no, a whole house filtration system won’t affect your water pressure, but only if you install the correctly sized filter and look after it properly.

Let’s look in more detail at whether whole house water filters restrict flow, and how to prevent your water pressure from dropping after installing a filtration system.

🤔 Why Does a Whole House Water Filter Affect Flow Rate?

Whole house water filters are designed to be installed at your main water pipe, so they shouldn’t interrupt your water pressure significantly.

There may be a slight slow down as water passes through the filter stages, and that’s because there’s resistance from the filters that reduces the flow of water. This helps the filter trap unwanted contaminants, so it’s important that flow rate is slowed somewhat – but it’ll usually only mean waiting a second longer for water to leave your faucets. The amount of water leaving your faucets shouldn’t decrease.

The average flow rate for a whole house water filter is 7-14 GPM.

Considering that the typical flow rate without a water filter is 6-12 GPM, you shouldn’t notice a difference in flow after installing a water filter.

📌 Factors That Affect Water Pressure After Installing a Whole House Filter

If you have noticed a significant drop in your water pressure after installing a water filter, here are some of the potential reasons why:

Factors affecting water pressure

Incorrect Filter Size

Buying the right-sized whole house filter system for your home is essential.

Most whole house water filtration systems come in at least two common sizes:

System Size# of BathroomsFlow Rate
Smaller1-37-10 GPM
Larger4-6~15 GPM

Let’s say you have a home or business with 4 bathrooms and you buy a system designed for homes with 1-3 bathrooms. This smaller system will have a lower flow rate which might be unsuitable for your home’s water pressure requirements.

The result? Your plumbing system can’t deliver water as quickly as it’s needed around your home, because your water flow is being slowed down by the filtration system.

Aside from the potential water pressure side-effects, it’s dangerous to buy an undersized whole house water filter, because the high flow rate of your water supply could damage the filters or crack the housing, resulting in leaking.

Poor Filter Quality

Some whole house filters are better than others.

A big aspect of a filter’s performance is its ability to effectively remove contaminants without significantly slowing down the flow rate. A poor-quality filter may only be able to do one or the other – or do both, but not very well.

If you want to prevent poor water pressure, make sure to buy a water filtration system that’s designed well.

Check customer reviews and read expert buying guides, like our best whole house water filtration system guide (read it here), so you know that you’re making a wise investment in a system that has a proven history of good performance.

High Number of Filter Stages

The number of filter stages affects the contact time between your water and the filtration system.

The more filters there are, the slower the flow rate. This is because it naturally takes longer for water to pass through a whole home filtration system with five separate filter cartridges, versus a system with a single cartridge.

In this case, we wouldn’t advise that you choose the single-cartridge system.

Filtration systems with more filter stages tend to provide a more thorough contaminant removal process. If contaminant removal is your goal, you might be happy to have a slightly slower flow rate for the benefit of drinking water that’s clean and properly filtered.

sediment filters

Clogged Filters

The filters in a whole house water filtration system don’t last forever.

The average lifespan of a cartridge filter in a whole house system is 6-12 months. Check your user manual to find out the exact lifespan of each of the filters in your system.

If you notice a gradual slowdown in water flow, it’s a good sign that one or several of your filters need changing.

Filters can become clogged faster than usual if your water quality is particularly poor, so you may need to change your filter cartridges earlier than expected if you experience significantly decreased water pressure.

Changing your clogged filters doesn’t only maintain your water pressure – it also ensures that the water you use for drinking and cooking purposes is clean and safe.

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

A flow rate of between 5 and 20 GPM is ideal for a whole house water filter system.

Why is this flow rate so varied? Because it depends on the size of your home, and the flow rate that you need.

  • Homes with 1-2 bathrooms should look for a water filtration system with a flow rate of 5-12 GPM
  • Homes with 2-3 bathrooms should use a water filter with a flow rate of 7-14 GPM
  • Homes with 3-4 bathrooms should buy a filtration system with a flow rate of 10-18 GPM
  • Homes with 4-5 bathrooms should aim to find a filter with a flow rate of 12-20 GPM

Most whole house filtration systems have a flow rate of at least 7 GPM. If you find a water filter system with a lower flow rate than this, it’s likely only suitable for apartments or small homes.

Household Size1-22-45-67-89-10
1-2 Bathrooms5 GPM7 GPM10 GPM10 GPM12 GPM
2-3 Bathrooms7 GPM10 GPM12 GPM12 GPM14 GPM
3-4 Bathrooms10 GPM12 GPM14 GPM14 GPM18 GPM
4-5 Bathrooms12 GPM14 GPM18 GPM18 GPM20 GPM

💭 Why is Water Pressure Important?

Now you know how to prevent a whole house water filter from causing a dip in water pressure, let’s look at why water pressure is so important in the first place.

Water pressure is a measure of the force of water flowing through your plumbing system. If your water pressure is too low, the speed of the water entering your appliances and leaving your faucets and shower heads will diminish.

Good water pressure allows your appliances to work properly, and lets you shower, wash your hands, and fill a glass with a good flow of water. So, if you currently have good water pressure, you don’t want to sacrifice this by installing a whole house water filter that slows your water flow right down.

Low water pressure

📈 How to Improve your Water Pressure

Poor water pressure isn’t always a sign of a problem with your whole house water filter.

Several other factors can affect water pressure, including:

  • Clogged pipes. If your pipes and hot water heater are clogged with sediment or hardness minerals, you’re likely to experience a steady decrease in water pressure.
  • Time of the day. Your water pressure will seem lower at peak water usage periods of the day, because your water needs to be divided between multiple appliances at once.
  • Demand and supply. It’s common for your water pressure to drop in the summer, when more people want drinking water, and water for watering their lawns or filling their pools.
  • Wrong pipe sizing. If your home’s pipes are too small compared to your water demand, you’ll probably have access to a slower flow of water than you need.

To improve the flow and pressure of your water, consider installing a pressure booster, which will boost water flow around your home. This will only work if you have access to the water in the first place, and your pipes are big enough to withstand an increase in flow. If you’re unsure, contact a local plumber and ask for their advice.