Leaking water · symptom guide
Sub-Zero leaking water in Mountain View
Water on the floor by a Sub-Zero almost never comes from where it lands. The usual sources are a frozen or blocked defrost drain, a water-inlet valve or supply line weeping behind the cabinet, condensation from a tired magnetic gasket, or an ice-maker overflow. Because the puddle migrates along the floor before you see it, the fix starts with tracing the path — not mopping up. We find the true origin, repair it with genuine OEM parts, waive the $89 service call with the repair, and back the labor for 365 days.
- Defrost drain, inlet valve, gasket or ice-maker — traced to the source
- Leaks over Eichler slab floors and upstairs condos handled fast
- $89 waived with repair · 365-day labor warranty
$89 service call, waived with repair · 365-day warranty on all labor
Where the water is really coming from
On built-in Sub-Zero refrigeration, four sources cover the large majority of floor leaks. The most common is the defrost drain: every cooling cycle melts a little frost that should run down a small tube to an evaporation tray, but on units that have run for years the drain ices over or clogs, so the melt backs up and spills out the bottom. Second is the water side — the inlet valve, the saddle or shut-off on the household supply, or the plastic fill line behind the unit can develop a slow weep that only shows as a puddle hours later.
The third source is condensation from a magnetic door gasket that has hardened and stopped sealing, letting humid room air meet cold surfaces and drip. The fourth is the ice maker: a stuck fill cycle, an over-fill, or a cracked mold can overflow into the freezer and find its way to the floor. Telling these apart is the whole job, which is why we trace before we replace.
Symptom guide
Where the water shows up → likely source → what we do
A quick map from where you find the water to the most likely origin on a Sub-Zero built-in.
| Where you see it | Likely source | What we do |
|---|---|---|
| Puddle at the base, no ice involved | Frozen or clogged defrost drain | Flush and clear the drain; check the evaporator |
| Water behind the unit | Inlet valve, saddle valve or supply line | Pressure-check the water side and reseal or replace |
| Drips inside the cabinet walls | Worn gasket / humid-air condensation | Test the seal and door alignment; renew the gasket |
| Water in or under the freezer | Ice-maker fill or mold overflow | Inspect the fill cycle, mold and shut-off |
| Pooling only in summer | Marine humidity meeting a weak seal | Confirm gasket, then check drain and door switch |
Tracing the origin first avoids repairs that don’t stop the leak.
Do not
What not to do with a leaking built-in
A few common reactions make the diagnosis harder or the damage worse.
- Don’t keep mopping and ignoring it — water tracks under the slab or to the unit below before it shows.
- Don’t pour hot water or jab a wire deep into the defrost drain; you can crack the tube or damage the evaporator.
- Don’t shove the unit back hard against the wall — you can kink or crush the water line.
- Don’t assume a new water filter alone fixes a leak; the source is usually the drain, valve or gasket.
- Don’t leave the supply on if water is actively running, especially in an upstairs condo — shut the valve and book.
Quick check
A two-minute check before you call
- 01
Find where it pools
Note whether the water is at the front base, behind the unit, inside the cabinet, or near the freezer — it points to the source.
- 02
Look behind for moisture
If you can see behind the unit, check the supply connection and line for any dampness or mineral crust.
- 03
Check the door seal
Run your hand around the gasket for gaps; a seal that no longer grabs paper can let humid air condense and drip.
- 04
Shut the water if it’s active
If water is actively running, close the unit’s supply valve, then note your model and serial and book a visit.
Why a slow leak gets expensive fast in Mountain View
The floors under Mountain View kitchens are unforgiving of standing water. In the Monta Loma Eichlers and other mid-century streets, the kitchen sits on a concrete slab with radiant heat tubing cast into it; a leak wicks under the cove base and along the slab edge before any sign appears at the surface, so by the time you spot it the cabinet kick and subfloor have already been wet for days. In the older bungalows around Old Mountain View, original oak and fir flooring cups and stains quickly once moisture gets under a built-in.
Upstairs is its own risk. In the condos and townhomes near Castro Street and throughout Whisman and Rex Manor, a leak that escapes the unit can reach the ceiling of the home below before anyone notices — which turns a small valve repair into a neighbor problem. That is why we treat an active leak as time-sensitive and trace it to its origin the same visit.
Condensation or a true leak? They are fixed differently
Mountain View sits in the marine-influenced mid-Peninsula, and the summer fog that rolls in off the Bay near Shoreline keeps kitchen humidity higher than people expect. That matters because a worn gasket or a propped-open door lets damp air condense on cold interior walls and run down — water that looks like a leak but is really humidity. We check the gasket seal, the door alignment and the interior frost pattern to separate condensation from an actual plumbing or drain fault, because patching the wrong one wastes your money.
How we trace and repair it
We confirm where the water is pooling, then work backward: inspect and flush the defrost drain, pressure-check the supply and inlet valve, examine the fill tube and ice-maker, and test the gasket seal around the full perimeter. Once we know the source you get an itemized quote before any work. Drain and gasket fixes are usually same-visit; valve and line repairs are quick once diagnosed; and every repair carries genuine OEM parts and a 365-day labor warranty.
Pricing
Typical leak-repair ranges
| Repair | Draft range |
|---|---|
| Defrost drain clear / flush | $160–$340 |
| Water inlet valve | $240–$520 |
| Supply / fill line repair | $180–$460 |
| Door gasket (condensation) | $400–$900 |
| Ice-maker fill or mold | $275–$650 |
Draft ranges only; the $89 service call is waived with the repair.
Reviews
What Mountain View homeowners say
Water kept appearing along the kick of our Eichler galley and I was terrified about the slab. They traced it to a frozen defrost drain, flushed it, and showed me the dry tray after. No more puddle, and they were careful with the mahogany panel.
Upstairs condo near Castro Street, so a leak is a real worry. They shut the supply, found a weeping inlet valve behind the unit, and replaced it with an OEM part the same visit. Calm and quick — exactly what I needed.
Thought our older built-in had a major problem. Turned out the gasket had hardened and summer humidity was condensing inside. New seal, dry cabinet, fair price, and a year of labor warranty. Honest work.
FAQ
Frequently asked questions
My Sub-Zero is leaking water onto the floor — what causes it?
The four common causes are a frozen or clogged defrost drain, a weeping water-inlet valve or supply line, condensation from a worn door gasket, and an ice-maker overflow. We trace which one it is rather than guessing, because each is repaired differently.
There’s water but the fridge is still cold — is it serious?
It can be. A cold unit that leaks is often a defrost-drain or gasket issue, which is usually inexpensive to fix but can damage flooring if ignored. Over an Eichler slab or in an upstairs condo it’s worth addressing quickly.
Could Mountain View’s humidity be causing it?
Sometimes. Summer fog off the Bay keeps kitchen humidity up, and a tired gasket lets that damp air condense inside and run down. We separate true condensation from a drain or valve leak before recommending a fix.
Is it the water filter?
Rarely the leak itself. An overdue filter can affect taste and flow, but floor water almost always traces to the defrost drain, the inlet valve or supply line, the gasket, or the ice maker. We check the actual source.
What should I do right now if it’s pooling?
Mop what you can, shut the unit’s water supply valve if water is actively running, and avoid pushing the unit hard against the wall. Then note your model and serial and book — especially if you’re upstairs over another home.
How much does a leak repair cost?
Most leak repairs run from about $160 for a drain clear to $900 for a gasket, depending on the source. You get an itemized quote on-site and the $89 service call is waived with the repair.
Water under your Sub-Zero?
Shut the supply if it’s active, then book — we’ll trace the source and stop it this week.
$89 service call, waived with repair · 365-day warranty on all labor