How To Fix A Keurig That only makes half a cup of Coffee

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If you’re experiencing a Keurig only making a partial cup, or a Keurig only makes a partial cup, or even your Keurig only filling half cup, you’re not alone.

This is a common issue that many Keurig users face, but don’t worry, there are several things that you can do to troubleshoot this problem.

Some common issues that can cause a Keurig coffee maker problems not brewing full cup include a blocked needle, low water level in the reservoir, or a clogged diaphragm valve at the bottom of the water reservoir.

If you’re wondering why your Keurig only brews a small amount or my Keurig only brews half a cup, it’s important to follow the troubleshooting steps outlined in this article to fix the issue.

Check The needle that punctures the k-Cups

First, check to see if there is anything blocking the needle.

The needle is what punctures the K-Cups and allows the water to flow through.

If there is something blocking the needle, it will not be able to puncture the pod and will not make a full cup of coffee.

half a cup of coffee

Check the water level in the reservoir

Check to see if the water reservoir is full. On some Keurig machines on on the back of the machine, and it may be hard to see the amount of water in the machine. Also some Keurig’s have a water sensor that prevent you from making coffee if the water is too low, so If it is not, then refill it and try again.

If you have tried these two things and still having issues the final step may fix your problem this is what finally fixed my problem and seems to be a very common issue.

Clean the diaphragm valve at the bottom of the water reservoir.

half a cup of coffee

Why Does The Valve Get Stuck?

Over time a scum can build up in the valve (gross I know) but this can clog the valve and prevent the water from being pulled from the reservoir properly, causing you to have a smaller cup of coffee.

How To Clean The Diaphragm Valve on a Keurig Machine.

1. Remove Reservoir

Start by removing the reservoir from the machine(it just pulls straight off).

2. Dump The Water

Dump all of the water out of the reservoir.

3. Flip The Reservoir Over And Locate The Valve.

The valve is a black tube on the bottom of the reservoir with a spring in it.

4. Brush The Valve

Using a brush and some soap and water scrub around the valve until all of the scum is gone. You may need to use a toothpick or something similar to get all of the scum out of the tiny hole in the valve.

5. Reassemble And Test

Reassemble your machine, add water and run a few test cups. This will flush the valve of any residual soap.


  • Soap
  • Water


  • Small Brush
  • Toothpick

How do I keep the valve from clogging in the future?

If your like me when you bought your Keurig it came with a filter to put over the valve at the bottom of the reservoir, and after a while you threw it away and never replace it…

Use that water filter! It may not totally prevent the valve from clogging again, but it will help.

The water filter are fairly inexpensive and can be bought in bulk on Affiliate LinkAmazon.

Premium 12-Pack Replacement Charcoal Water Filters for Keurig Coffee Machine


Hopefully you’re now enjoying a full cup of coffee, and aren’t too grossed out by what you had to clean out of your coffee maker.

If you have any other questions feel free to contact me and I will do my best to answer them!