Sub-Zero 7042803 Ice Maker Water Filter (UC-15I): The Complete Guide

If you own a Sub-Zero UC-15I undercounter ice maker, there's one small part that has an outsized effect on how your ice looks, tastes, and smells: the water filter. The genuine part is the Sub-Zero 7042803 (it replaces the older 7012333), and keeping a fresh one in place is the single easiest thing you can do to protect both your ice and the machine that makes it.

This is your complete owner's guide. We'll cover what the 7042803 actually does, how often to replace it, how to tell when it's overdue, why "genuine OEM" matters on a machine this expensive, and the questions Sub-Zero owners ask us most.

What is the Sub-Zero 7042803 ice maker filter?

The 7042803 is the genuine OEM water filter cartridge for the Sub-Zero UC-15I and UC-15IP undercounter ice makers. It sits inline on the water supply feeding your ice maker and reduces sediment, chlorine taste, and odor before the water ever freezes into a cube.

Here's why that matters more than people expect: ice is basically frozen tap water, and it picks up every off-taste and smell the water carries. A tired filter lets chlorine, minerals, and musty odors straight through, and then you're serving that in a glass of ice water or a cocktail. 👉 If your ice has started tasting "off," the filter is almost always the first thing to check.

The 7042803 is a genuine Sub-Zero part built to the exact tolerances of the UC-15I housing, so it seats correctly and flows at the rate the machine expects. You can find it here: the genuine Sub-Zero 7042803 UC-15I ice maker water filter.

How often should you replace the 7042803?

Straight from Sub-Zero: replace the water filter on the UC-15I(P) every six months, after any prolonged shutdown, or whenever the red REPLACE FILTER light comes on. Whichever happens first is your cue.

Six months is the baseline, but a couple of things can move that date up. If you're on well water or have hard, heavily chlorinated municipal water, the filter works harder and clogs sooner. If the machine sat unused during a vacation, a seasonal closing, or a renovation, replace the filter when you fire it back up rather than trusting stale water that's been sitting in the line.

👉 One easy habit: write the install date on the filter with a marker, or set a recurring calendar reminder. It's the kind of thing that's simple to forget and simple to stay ahead of.

Signs your ice maker filter is overdue

Your ice maker will usually tell you it's time, one way or another. Watch for:

• The red REPLACE FILTER indicator — the most direct signal, and the one Sub-Zero built in for exactly this.
• Ice that tastes or smells off — chlorine, staleness, or a musty note usually points at the filter.
• Cloudy or smaller cubes — reduced flow from a clogging filter can change how cubes form.
• Slower ice production — when water can't move through the filter freely, output drops.
• It's simply been six months — even if nothing seems wrong, the media is spent on schedule.

None of these are emergencies, but they're all fixable in a few minutes with a fresh cartridge.

Isn't this the same as my refrigerator water filter? (No.)

This trips people up constantly, so let's clear it up. The 7042803 is for the undercounter ice maker. It is not the same as the filter inside your Sub-Zero built-in refrigerator — that's the Sub-Zero 4204490 refrigerator water filter (which replaced the older 7023812). Different machine, different housing, different part number.

If you own both a Sub-Zero fridge and a UC-15I ice maker, you have two separate filters on two separate schedules. Not sure which cartridge your appliance takes? Our model-by-model guide to which Sub-Zero water filter you need walks through it by appliance.

Genuine 7042803 vs. cheap aftermarket filters

You'll see aftermarket cartridges online for a few dollars less, and on a $6 fridge filter maybe that's a debate. On a Sub-Zero undercounter ice maker, it isn't. Here's the honest comparison:

A Sub-Zero ice maker is a premium appliance, and a leak or a bad seal from a loose-fitting cartridge can cost far more than the few dollars you'd save. The genuine part is cheap insurance.

How to replace the 7042803 (the quick version)

Swapping the filter takes only a few minutes and no tools. In short: locate the filter in the ice maker, turn the old cartridge to release it, insert the new 7042803 and lock it in, then run and discard the first batch of ice so any loosened carbon fines flush out. Reset the filter indicator if your model prompts you.

👉 That "throw out the first batch" step matters — it's how you get clean, clear cubes right from the start. For the full walkthrough with photos, see our detailed guide on how to replace your Sub-Zero 7042803.

Frequently asked questions

What filter does the Sub-Zero UC-15I use?

The genuine part is the Sub-Zero 7042803, which replaces the older 7012333. It fits the UC-15I and UC-15IP undercounter ice makers.

How often should I replace the ice maker water filter?

Every six months, after a prolonged shutdown, or when the red REPLACE FILTER light comes on — whichever comes first.

Is the 7042803 the same as my Sub-Zero refrigerator filter?

No. The refrigerator uses the 4204490 (formerly 7023812). The 7042803 is only for the UC-15I ice maker.

Do I really need to throw out the first batch of ice?

Yes. The first batch after a filter change can carry harmless carbon fines and should be discarded so your ice comes out clean and clear.

Can I use an aftermarket filter instead?

You can, but on a premium ice maker we don't recommend it. Genuine OEM tolerances protect the seal, the flow rate, and the machine itself.

The bottom line

The Sub-Zero 7042803 is a small, inexpensive part that quietly does a big job: clean, clear, great-tasting ice and a healthier ice maker. Replace it every six months (or when your machine tells you to), always choose the genuine OEM cartridge, and remember that your fridge and your ice maker are on separate schedules with separate filters.

Ready for fresh ice? Grab the genuine Sub-Zero 7042803 UC-15I ice maker water filter and keep a spare on the shelf so you're never caught off guard when that REPLACE FILTER light comes on.

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