The phone worked. That was the whole problem.
A buyer picked up a two-year-old Android that passed every check he ran — screen clean, battery fine, cameras sharp, network registered. Eleven weeks later the charging port started refusing cables at certain angles, then the bottom microphone went, then the phone stopped charging entirely.
None of it was bad luck. The device had been in water at some point before he owned it, and corrosion had been quietly working through the board the entire time he was using it happily.
Water damage is the only common fault that reliably passes inspection and fails later. That’s what makes it worth its own set of checks.
Why “water resistant” doesn’t mean what people think
Modern phones carry IP ratings, and those ratings are real. They’re also narrower than the marketing implies.
Ratings are established in controlled laboratory conditions — fresh water, a specified depth, a specified time, no pressure, no movement. Real exposure involves salt water, soap, chlorine, hot water, or a phone being moved through liquid, all of which behave differently.
More importantly, resistance degrades. The seals and adhesive that create it age, and any repair that opens the device ends it unless the seals are properly replaced. A three-year-old phone that has had a screen fitted at a walk-in shop has, for practical purposes, no water resistance at all regardless of what the box said.
And every major manufacturer excludes liquid damage from warranty coverage, which tells you how they regard the rating themselves.
The liquid contact indicator
The first place to look, and it takes four seconds.
Phones carry small stickers that change colour on contact with liquid — white or silver when dry, pink or red once triggered.
On iPhone, the indicator sits inside the SIM tray slot. Pull the tray and look into the opening with a light, or check the tray itself.
On most Android phones, it’s in the SIM or memory card slot too, though placement varies by manufacturer. Some models have additional indicators inside the case that you won’t see without opening it.
The gap worth knowing about: phones with no SIM tray at all — including US models of recent iPhone generations, which are eSIM-only — remove this check entirely. There’s no tray to pull, so you’re relying on the other signs below.
A triggered indicator isn’t proof of damage. Humidity and steam can set one off without any harm being done. What it does is shift the burden: a red indicator means you need much stronger evidence from everything else before you buy.
Physical signs of corrosion
Where liquid has been, corrosion follows, and it appears in the same places.
The charging port. Take a light and look in properly. You’re looking for green or white powdery deposits on the pins, discoloured metal, or pins that look dull rather than bright. Compacted grey lint is common and harmless; corrosion looks chemical rather than fluffy.
The SIM tray and its slot. Rust marks on the tray, or discolouration around the opening.
The speaker and microphone grilles. Deposits or staining around the openings at the bottom edge.
Under the screen glass at the edges. Faint watermarks, cloudiness, or a slight discolouration ring visible on a white background.
The headphone jack, on phones that still have one — a classic collection point.
Corrosion has a distinctive look once you’ve seen it. Bright metal that’s gone dull, or coloured residue where there should be none.
Where to look, and what you’re looking for
| Location | How to check | What’s a problem |
|---|---|---|
| SIM tray slot | Pull the tray, use a light | Pink or red indicator instead of white/silver |
| SIM tray itself | Look at both faces | Rust marks or discolouration |
| Charging port | Light, straight down the opening | Green or white residue, dull pins |
| Speaker and mic grilles | Angle under light | Staining or deposits around the openings |
| Screen edges | Plain white background, full brightness | Watermarks, cloudiness, a discoloured ring |
| Camera lenses | Photo in low light | Haze or spotting that cleaning won’t remove |
| Headphone jack, if present | Light | Corrosion inside the barrel |
| Screws by the charging port | Close look | Chewed heads, suggesting the phone was opened |
That last row belongs on a water damage list for a specific reason: a phone that’s been opened for a liquid clean is a phone that had liquid in it. Signs of disassembly on a device the seller describes as untouched deserve a direct question.
Symptoms that suggest past exposure
Functional signs, which are worth testing precisely because a corroded phone often works partially.
- Charging that works at some cable angles and not others
- The bottom microphone sounding muffled while the top one is fine, or vice versa
- A speaker that crackles at volume
- Intermittent touch response in one region of the screen
- Wi-Fi or Bluetooth that drops in ways signal strength doesn’t explain
- A camera with a faint haze or spotting that no amount of cleaning removes
- Buttons that need a firmer press than they should
One of these is probably nothing. Two or three together, on a phone with a triggered indicator, is a pattern.
The delayed failure problem
This is the reason water damage deserves more caution than a crack does.
A cracked screen is fully visible and fully priced. Liquid exposure is a process. Corrosion spreads across contacts and connectors over weeks and months, and the phone fails progressively — one component, then another, in no predictable order.
Which means a phone that’s been in water can genuinely pass every test you run at the meetup and still be on a trajectory. You aren’t testing whether it works. You’re trying to establish whether the process has started.
That asymmetry is why my position on this is harder than on most faults: on any phone with real value, a triggered indicator plus any corrosion sign is a walk-away, not a negotiation. You cannot price a fault whose timing and extent are unknowable. Repairs on liquid-damaged devices are similarly unpredictable, which is why our repair-or-replace guide puts them near the bottom of the worth-fixing list.
Asking the seller
Two questions, and the second is better than the first.
“Has it ever been in water?” invites a no.
“Has it ever been wet — rain, a spill, a bathroom shelf, a pocket in a downpour?” invites a more honest answer, because it describes situations people actually remember and don’t consider damage.
Plenty of exposure is innocent. A phone caught in rain on a walk home is not the same as one dropped in a sink. What you’re trying to establish is whether liquid has been inside, and the specific story usually tells you more than the yes or no.
One further check, if the seller allows it: ask whether the phone has been opened for a cleaning at any point. A device that was professionally cleaned after exposure is in a genuinely better position than one that was dried in a drawer and hoped for, because ultrasonic cleaning removes the residue that becomes corrosion. It’s still a phone that was wet — but the difference between treated and untreated exposure is real, and a seller who had it done properly will usually have a receipt.
While we’re here: rice doesn’t work
Worth stating because the advice persists.
Uncooked rice is not meaningfully absorbent at the scale that matters, doesn’t reach inside a sealed device, and adds a new problem — starch and dust getting into ports. Apple’s own guidance advises against it explicitly.
What actually helps a recently wet phone: power it off, don’t charge it, don’t use heat, remove any tray to open an air path, leave it somewhere dry with moving air for a good while, and get it professionally cleaned if the exposure was anything worse than a splash. Ultrasonic cleaning at a repair shop genuinely removes residue that would otherwise become corrosion; a bowl of rice does not.
If you’re buying and the seller mentions the rice trick, you’ve learned the phone has been wet.
Buying a phone advertised as water damaged
Occasionally sellers are upfront about it, and the price reflects it. Worth knowing when that’s a reasonable purchase.
Reasonable: you want a parts device, you’re buying it at parts pricing, and you have somewhere to sell or use the components. Screens, cameras, and housings from a liquid-damaged phone are often perfectly fine, since corrosion concentrates around the board and connectors.
Reasonable: a disposable secondary device where failure costs you nothing — a phone for a workshop, a dashcam, a device that lives on a shelf running one app.
Not reasonable: a daily phone at a discount. The discount never covers the risk, because the timeline is unknowable and the failures arrive one after another.
If you do buy one, assume the price you pay is the total value you’ll get. Don’t plan to repair it, don’t plan to resell it, and don’t put anything on it you’d miss.
Common mistakes to avoid
- Trusting the IP rating on a used phone. Seals age and repairs void them.
- Skipping the SIM tray. Four seconds for the most direct evidence available.
- Treating a working phone as an undamaged one. Corrosion is progressive.
- Negotiating a discount on a liquid-exposed phone. You can’t price an unknown timeline.
- Ignoring a single odd symptom. Muffled mic plus a red indicator is a pattern, not a coincidence.
- Assuming eSIM-only phones can be checked the same way. No tray, no indicator, more reliance on everything else.
- Buying a liquid-damaged phone cheaply “for parts.” Fine if you genuinely want parts, expensive if you were hoping it would hold.
FAQ
Where is the liquid contact indicator on a phone?
Usually inside the SIM tray slot on both iPhones and most Android models. Pull the tray and look into the opening with a light. Phones without a SIM tray don’t offer this check.
Does a red indicator always mean the phone is damaged?
No. Humidity and steam can trigger one without harm being done. It means the phone has been in a wet environment, which raises the standard of evidence you should want from every other check.
Can a water-damaged phone work normally for months?
Yes, and that’s the danger. Corrosion progresses slowly, so a device can pass every inspection and start failing components weeks later.
Is water damage covered by warranty?
Generally no. Major manufacturers exclude liquid damage from standard warranty coverage regardless of the phone’s IP rating.
My phone got wet and still works. Should I sell it?
You can, and you should disclose it. Selling a device with known liquid exposure without saying so is how disputes start, and buyers who discover it later have a legitimate complaint.
Does the liquid indicator ever reset or change back?
No. The dye change is permanent, which is why it’s useful evidence. A tray showing white on a phone the seller admits was wet usually means a replacement tray, which is itself worth asking about.
Can a repair shop tell me if a phone has been wet?
Yes, and more reliably than you can from outside — opening the device reveals internal indicators and any corrosion on the board. If you’re considering an expensive used phone with an ambiguous history, an inspection before purchase is money well spent.
Is a liquid-damaged phone ever worth buying?
Only as a parts device at a parts price, or as a disposable secondary phone you won’t mind losing. Not as a daily driver at a discount.
Make the SIM tray your first move at every viewing — before the screen, before the battery menu. It’s the fastest four seconds in the entire inspection and it changes how you read everything that follows.
Shopping now? Browse listings on ExploreFrag and run the ten-minute fault test alongside this.
About the author
Emran Ahmed is the founder and CEO of ExploreFrag, a marketplace for buying and selling used phones and accessories across every brand. Liquid damage is the fault he’s least willing to negotiate on, because it’s the only one that reliably passes inspection and fails afterwards. He checks the SIM tray on every phone he handles, out of a habit he’d recommend to anyone.