Why is My Ice Machine Full of Water?

The simple answer is because your drain is clogged. The long answer is if your bin is full of water it usually isn't your ice machine. It's just your bin.


There are two form factors of ice machines:


The first form factor is an ice machine head with a storage bin. The ice machine head is what produces the ice. It houses all of the mechanical ice making equipment. There is a large variety of ice machine heads which can produce from 300-2000+ pounds of ice from cube to nugget ice. This head makes the ice and drops it into the ice bin for storage. Below is an image of an ice machine head outlined in red.

Manitowoc Ice Machine Head at a Local Austin Charity
Manitowoc NXT Indigo Modular Head

However, the bin is often the source of visible clogging. The bin does two things. It holds the ice and drains as the ice melts. The bin is not a freezer. It is only insulated and slows down the ice melt. What causes the drain to get clogged 95% of the time is mold because the ice bin is mold’s favorite place to grow. Mold loves cool, damp dark places and your ice bin is the perfect opportunity for massive growth. That mold builds up in the bin but also builds up in the drain pipe from the bin to your sewer. This build-up in the drain line is often missed when you empty all of the ice out of your machine and clean it. When left alone long enough it will clog the drain preventing the ice melt from draining and eventually fill the bin with water. What do you have to do to get rid of it? Pull all of your ice out and clean the bin and drain line with a sanitizer that can kill and dislodge the mold. Below is an ice bin outlined in red.

Manitowoc Ice Bin B570
Manitowoc Ice Bin at a local Austin Charity

There is another possible reason for the ice machine and bin drain to be clogged. Scale. In fact scale can build up so much that a host of issues can stop your ice machine from even making ice. Scale can build up in your water valves, your water pump, on your evaporator and or course in the drain lines. If you are lucky enough to live somewhere where scale build up in your water system is not an issue, I’ll elaborate, you lucky dog. Scale in water slowly builds rock formations everywhere water travels and in this instance it builds up in your ice machine water system. If caught before it builds up too much, scale can be dissolved by things as simple as vinegar* which reacts with the scale hissing and bubbling away the rock build up. If left too long the scale build up is so thick that it will not dissolve or has caused mechanical failures requiring parts to be replaced. Below is a picture of a drain line from an ice bin so clogged with scale that the entire drain line was replaced.

Ice machine drain line completely stopped up with scale build up
Scale Build up on Ice Machine Bin in South Austin

Drains are far too often plumbed wrong for most ice machine head with bins. Unless your ice machine is a residential undercounter ice machine the drain should always be plumbed with ¾” PVC with a vent to allow proper drainage. Your bin should be drained separately from the ice machine if possible with ¾” PVC as well. If you see ½” PVC or flexible drain line without a vent it is done incorrectly and will cause drain issues. Below is an image of how to properly run a drain line from an ice machine and an image of how not to run your ice machine and bin drain line.

Properly plumbed and drain commercial ice machine
The Right Way to Plumb and Ice Machine Drain

improperly installed commercial ice machine with kink in plastic tubing
The Wrong Way to Plumb an Ice Bin Drain. This Does Not Work.

The second form factor of an ice machine is an under counter ice machine. The under counter ice machine has everything in one package. The machine makes the ice and has a bin to hold the ice all in one. These machines range 65 up to 300 pounds of ice per day and can store about 130 pounds in its internal bin. There is only one drain on this machine and when it clogs it will back-up into the machine itself. This drain has the same mold and scale issues as the other type of machines and can be cleared out in the same way. This machine’s drain lines should also be plumbed with ¾” PVC as well but sometimes these machines are jammed into little spaces where proper plumbing is not possible and unvented flexible tubing is the only option. When the flexible drain tubing is used it will clog considerably more than PVC. You are probably familiar with this type of under counter ice machine but I’ve attached an image below.

Koolaire undercounter commercial ice machine
Koolaire Under Counter Ice Machine at an Austin Regional Clinic

There is another situation that can back up water into your bin in an under counter ice machine. Your ice machine has a drain pump that is clogged or is not working. You’ll find this type of drain pump system in smaller ice machines often found in residential or small office spaces. Below is an example of a 15" wide ice machine designed to go in a small kitchen or kitchenette.

New Hoshizaki nugget ice machine being installed in austin texas
Hoshizaki C80-BAJ Nugget Ice Machine Ready to Install in Austin

Often, these machines are not in a place where there is a drain in the floor or below the level of the ice machine. In light of this, manufacturers offer the option to have an internal pump to drain water from the ice machine that otherwise could not get out. Depending on the manufacturer, the pumps are controlled by a pressure switch or a float switch. The pressure switch is separate from the pump and can get clogged fairly easily and when clogged will either run the pump non-stop or not run it at all. This pressure switch and pump can be found in Scotsman and Ice-O-Matic ice machines and typically is a common reason for water in the ice machine. The float switch drain pump is just that: a switch with a float that turns on the pump when the water level rises. The float switch is a superior switch style pump. The switch is integrated into the pump and fails considerably less. It can be found in Hoshizaki and Manitowoc ice machines. These pumps both can fail and stop pumping out the water. One advantage of these pumps is that they have kill switches in the pump wiring that will shut off the ice machine rather than keep making ice until water overflows out of the bin. Below is a drain pump from a Scotsman ice machine.


drain pump on commercial grade residential scotsman ice machine
Scotsman Ice Machine Drain Pump at a Residence in Lubbock

Below is a picture of a Hoshizaki ice machine drain pump.


Hoshizaki undercounter nugget ice machine for residential application internal drain pump
Hoshizaki Drain Pump for a Nugget Ice Machine in Lubbock

Depending on your situation the above explains why your drain is clogged and gives you some ideas of how to solve it. One thing you can do to keep your bin from clogging up is by doing semi annual cleaning of your machine. We offer recurring service to our customers to descale and sanitize our customer’s ice machine and bins. Not only does this keep the bin clean and draining correctly, it also keeps the ice machine parts clean so they can perform well. If you need help with your ice machine or bin, give us a call at 512-651-4565 in Austin and Lubbock, Texas (806) 787-4985 Or Visit our website at www.tripointrefrigeration.com

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*Vinegar may work well to dissolve scale but be sure that the vinegar will not damage the parts caked with scale. There are specific ice machine descalers that will not damage metals inside your ice machine. If you are not sure, ask for help.

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