How to clean a countertop ice maker

Two things build up inside an ice maker, they look similar, and they need different treatment. Confusing them is why people scrub a machine and find the smell comes back in a week.

Scale is mineral

Hard water carries dissolved calcium and magnesium. When water freezes or evaporates, those minerals stay behind as a chalky white or gray crust on the evaporator, the pump and the water path. Scale does not smell. What it does is insulate the cold surfaces, so cycles get longer, cubes get smaller and cloudier, and eventually the machine stops making ice at all. Scale is dissolved by acid - vinegar or citric acid - and nothing else you have in the house.

Biofilm is biological

Standing water at room temperature in a dark plastic box grows a slick layer of bacteria and, given long enough and some air exposure, visible mold. This is the source of the musty smell and the off taste, and it is the reason a machine left full of water for three weeks in a warm kitchen is worse than one used every day. Biofilm needs to be physically wiped off the surfaces you can reach and flushed out of the ones you cannot.

Both are predictable consequences of the design rather than defects. A countertop machine has no plumbing and no drain-to-waste, so by definition it holds standing water. The whole maintenance routine is about not letting that water stand for long.

1. Unplug it and empty it. Pull the bin, dump any ice, and drain the reservoir through the drain plug or by tipping it into a sink. Ice that has been sitting in the bin absorbs everything in the machine - it goes down the drain, not in a glass.
2. Wipe what you can reach. A soft cloth with warm water and a drop of dish soap over the bin, the reservoir walls and the lid seal. This is where visible biofilm lives, and no cycle reaches it. Rinse the soap out thoroughly.
3. Mix the descaler. Roughly one part white vinegar to ten parts water is the standard starting dilution, or food-grade citric acid at the concentration on the pack. If your manual specifies a branded cleaner, use that instead at its printed dilution - a few makers exclude acid damage from warranty cover.
4. Run a full cycle with the solution. Fill the reservoir with the solution, plug the machine in and let it make ice. The point is to circulate acid through the pump and over the evaporator, which is where the scale you cannot see actually is. Discard that ice.
5. Let it dwell if the scale is heavy. If cycles had got long and the cubes small, leave the solution sitting in the reservoir for twenty to thirty minutes before you run it, then run it. Acid needs contact time.
6. Rinse with two or three plain water cycles. Drain, refill with fresh water, cycle, drain again. Repeat until there is no vinegar smell at all. Under-rinsing is the single most common mistake and it is why people end up with faintly sour ice.
7. Throw away the first full batch. Not because it is dangerous, but because it will taste of the clean. The second batch is the one you drink.
8. Dry it with the lid open. Leave the reservoir empty and the lid open for a few hours. A dry machine grows nothing, which is why this step matters more than any other if you use the machine occasionally.

Never use bleach, a dishwasher tablet, a scouring pad or an abrasive cream inside an ice maker. Bleach residue in a water path is genuinely hard to rinse out, and scratched plastic gives biofilm more surface to hold on to than it had before you started.

If you are on hard water, a scale-inhibiting filter is better value than any cleaning routine, because it stops the mineral arriving rather than removing it afterwards. The GE Opal sells one as a consumable (P4INKFILTR) and the point of a consumable is that it gets consumed - see the Opal 2.0 review for what that costs in attention.

• Ice smells or tastes musty: biofilm in the reservoir. Wipe, descale, rinse hard, then dry with the lid open. If it returns in a week, you are storing the machine with water in it.
• Cubes getting smaller or cloudier: scale insulating the evaporator. Descale with a dwell. See why is my ice cloudy if the cubes were always cloudy rather than recently so.
• Cycles getting longer: scale, or blocked airflow. Descale, then pull the machine 4 to 6 in off the backsplash so it can reject heat.
• Visible black or pink specks: mold or a pink-pigmented bacterium, both common in standing water. Full clean, and from then on store it dry.
• Machine runs but makes no ice: past the point cleaning fixes. Check the water level sensor and the manual's error codes before assuming scale.
• Ice tastes faintly sour after cleaning: vinegar residue. Run two more plain-water cycles and discard the ice.

One habit removes most of this list: never leave water in a machine you are not using. Everything that grows inside an ice maker needs standing water, and draining takes a minute.

A spotless machine does not help if the ice goes into a bucket you last washed in spring, or gets handled with fingers, or sits in meltwater all evening. Stainless buckets go through the dishwasher; the tongs should too. How to store clear ice covers keeping a batch clean once it leaves the machine, and how to clean bar tools covers the rest of the station.

If you use molds rather than a machine, the same logic applies in a simpler form: silicone absorbs odors over time, so run molds through a dishwasher cycle periodically and store them dry rather than in the freezer full of old water. Best clear ice molds covers the hardware.