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How Does the PUR Water Filter Light Work? Let’s Find Out Right Now!

Fact checked by Stephen Conklin

How Does the PUR Water Filter Light Work

Have you ever wondered why your PUR water filter has LED lights? While you may think they look cool and futuristic, these lights have a very important function. They give you an idea of whether your water filter is working or not. I know you have been itching to ask, how does the PUR water filter light work?

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Why Do PUR Water Filters Have LED Lights?

If this is your first time owning a PUR water filter, you may have already noticed one or a few LED lights on your appliance. You can see these lights on a PUR water filter pitcher, dispenser, and faucets.

PUR water filters are like any other modern device you may have. Look at your mobile phone, and you may see a small LED light at the top of the screen. If your screen is off, you know if you missed a call or message when you see a blinking light. It alerts you to check your phone.

The same is true with PUR water filters. These devices do not have voice assistants to tell you when to change the filter or something is wrong with the unit. Instead, PUR decided to integrate lights to catch your attention.

Essentially, the LED lights are notifications for the water filter’s current status. You will know if the filter is ready to deliver safe drinking water to your glass or not. More advanced models can also provide you with flashing or blinking lights. It would be impossible to miss these.

How Do These Lights Work?


Many people think of water filter indicator lights as a form of sophisticated technology. While that may be true, a water filter light is nothing more than a timer or counter.

No one knows precisely how the PUR water filter light or that of any other brand works. Is it a trade secret? No one in the ordinary world of men knows.

However, the current opinion is that the light mechanism connects to a digital timer or counter. It tracks the number of times you’ve refilled your pitcher and computes the average volume of water you pour into a glass.

For a PUR faucet filter, the mechanism can be a bit more complicated. When you open your tap, a sensor tracks the volume of water passing through the filter, relying on a predetermined water volume, and factoring in the flow rate.

Both methods have two predetermined thresholds. When the filter unit reaches the first threshold, it sends a signal to the controller to change the LED color. Reaching the second threshold level also changes the LED’s color.

Let us try to understand this a little bit.

When you look at your PUR filter, you may see that it has a filter lifespan of two months or 40 gallons. These numbers are the absolute thresholds of your unit. Some products may have a longer filter lifespan.

The point is that when your filter senses that it is nearing the 40-gallon mark or the 60th day, it activates the LED to show a different light color. The first color change you see warns you that your filter is near the end of its service life. You can still enjoy a few more gallons or so.

Once the LED switches to another color, it is a sign that your PUR water filter has already reached its end. You should never use your filter again. The only action to take now is to replace the filter.

Some people think that PUR water filters have advanced sensors that measure the number of particles or sediments present in the filtration membrane. The theory is that the system controls the LEDs depending on water contaminant levels.

However, I cannot say I agree with this theory. First, there is no contact between the LED control box and the filtration membrane. Second, I have yet to see sensors in the filter cartridge or membrane itself. Even if there are sensors, I cannot see any wire that connects the sensors to the control module.

But hey, if you think otherwise, I sure would love to hear your thoughts and share them with everyone else.

What Do the Different Colors Mean?


PUR water filter lights have three different colors corresponding to the filter status. You might want to check your owner’s manual to see what the various light shades represent. For example, a steady, solid light can indicate normal operation, or it may be a sign of a problem.

Interestingly, PUR and other water filter brands almost always use a traffic light color scheme. Maybe they designed their water filter lights for instant recognition.

  • Green

Like the traffic light on a busy intersection, the color green indicates your filter is all good to go. You can drink the water from the unit safely.

You might notice your water filtration unit with a blinking green light right after filter replacement. There is no need to worry about it because your water filter only tells you that it is ready to serve safe, great-tasting, and clean water.

There are other instances when the unit has a flashing green light. For example, cleaning your filter and putting it back will often set off the green flash when you restart the filtration system. As long as the color is green, there is no cause for concern.

  • Yellow

A flashing yellow LED notifies you that your PUR water filter is near its end. Unfortunately, no one knows how many more gallons you can enjoy before the filter is useless.

One thing you must know is that the yellow light serves as your warning. It gives you sufficient time to collect your pennies and dimes to purchase a replacement filter.

  • Red

You already know by now what a flashing red light means on your PUR water filter — it can no longer filter your water as effectively as it used to.

While it may be tempting to continue using the filter despite the red light indicator, I beg you not to. There is no way of knowing whether you already have harmful contaminants in your drinking water. I think you should learn more about the lifespan of the PUR water filter. I believe it will help you.

How Can I Reset My PUR Water Filter Light?

If your PUR water filter starts blinking yellow, you will soon have to purchase a replacement filter. Of course, you can wait until the light turns red before changing the filter to make the most out of your investment.

Once replaced, you must reset the water filter light. It is wise to remember that your device keeps track of the water volume you consume. If you do not reset it, your filtration unit will emit a flashing red light.

Resetting your filter light is as easy as pressing and holding the RESET button for about five seconds. This action will move its ‘counter’ or ‘timer’ to start at zero.

When you operate your filter for the first time after filter replacement, you should see a blinking green light before it steadies into a solid color.


If you ever wondered “how does the PUR water filter light work,” now you know. The system works by monitoring your filter usage and alerts you when it is time to replace the filter. You can look at it as the water filter version of an ordinary traffic light.

Green is for a well-functioning water filter, while yellow prepares you for an impending filter change. The red light is your sign that you must replace the filter at once.

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