Automatic Keurig Filler

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The Story

Call me lazy, but I can't stand the idea of constantly refilling my Keurig water. Since it was sitting right next to the sink I decided to run a water line and set up a way to automatically refill the container.

NOTE: I consider myself pretty handy, but plumbing is one area that always makes me nervous. Anytime I work with water I make sure I'll be around for a while to check for leaks.


First I needed a way to get water to the Keurig. I got this nice Icemaker water line kit from Amazon for a quick and easy water line addition under the sink. I drilled a 1/4 inch hole through the corner of my stainless steal sink and used rubber grommets to protect the water line from rubbing against the sink. Finally, I put a 1/4 inch valve in line so I could turn the water on and off easily while working on the fill control.

Icemaker kit connected to cold water The Keurig


I've tried 2 different control methods and I'll cover both here.

Mechanical Control ~$8

I started out with a simpler and cheaper mechanical control for the water flow. For about $8 you can get a float valve, commonly used to keep fish tanks at the proper water levels. The problem I ran into with this method is finding room for the float inside the pitcher. My Keurig model has the water filter inside the tank, which means there's a big tab sticking up for you to pull the filter out for replacement. This tab doesn't leave much room for a float to function properly. You have to hold the float valve to the lid of the water tank to see where it looks like the float will fit, between the filter tab and the back of the tank. The float valve I used had an adjustable float arm that helps to let it fit in the tight space. Even with this the valve on mine didn't always close all the way. I ended up waiting till the tank got low and then opened the shutoff valve. When the water got high enough the float valve would at least slow down the flow until I turned the shutoff valve back off. More careful placement of the float valve in the tank lid and/or removing the water filter would make this control much more reliable.

Electronic Control ~$30

Since the mechanical control didn't work out for me I started working on electronic flow control. The electronic controls system I'm setting up can be 3-4 times the cost of the simple mechanical control, but the end result will be more reliable. I started with 3 components: a 12V/1A power supply, a normally open dual float switch, and a normally closed 12V solenoid valve.

The problem with only using these 3 components is the float switch quickly turns on and off every time you use the Keurig, which can shorten the life of the solenoid and the float switch. To resolve this you can add a relay to the circuit so that the lower float causes the water to turn on and the upper float causes the water to turn off.

Float Control Circuit

You can see an interactive simulation of this circuit at this link. In the simulation you can click on the bottom and top switches to see how the circuit works. As the water lowers it closes the top switch and then the bottom switch. The output of the top switch feeds through the relay and ties into the output of the bottom switch and the relay coil input, latching the relay until the water is high enough to open the top switch. The resistor in the circuit represents the solenoid.

Since the solenoid is normally open when you lose power nothing happens. This way you don't have to worry about the tank overflowing when it storms.

Finished Product

I wrapped the hole thing up in a project box for a clean, finished look. The project box I used is about 5 inches long x 3 inches wide x 2 inches deep.

This box is about the perfect size, leaving a comfortable amount of space aside the solenoid to fit the external connections and the relay necessary to prevent short cycling the valve. I put one hole in the end for the wiring to pass through and a hole on both sides for the water to come in and out.

Assembled Electronics Finished Control Box

Make sure to mount he float inside the tank where the top float is sure to be triggered before the container overflows.

Float Mounted in Tank

Enjoy and feel free to report any problems or suggestions to