Dishwasher Not Cleaning Dishes? 5 Causes, Including LA Hard Water
From LA appliance technicians: why the hard water in your tap can be the root issue, and how to fix it.
In this guide
Why LA dishwashers struggle — the hard water reality
LADWP’s water-quality FAQ puts the water it supplies in the hard range. Its 2022 hardness figures by area:
| LADWP area | Average hardness | Range |
|---|---|---|
| San Fernando Valley and Western Los Angeles | 8.6 grains per gallon (147 mg/L) | 5.4–16.1 gpg (93–275 mg/L) |
| Silver Lake, Downtown and South Los Angeles | 9.8 grains per gallon (168 mg/L) | 5.4–17.0 gpg (93–291 mg/L) |
| Eastern Los Angeles and the Harbor | 16.3 grains per gallon (279 mg/L) | 16.1–16.4 gpg (275–281 mg/L) |
On LADWP’s scale, under 4 grains per gallon is soft, 4 to 7 is medium-hard and anything above 7 is hard. LADWP also notes that even its hardest water does not need softening to be safe or usable: the issue for appliances is scale, not safety. If your city runs its own water utility, as Santa Monica and Beverly Hills do, check that city’s water-quality report instead.
Over the years, that scale builds up on spray arms, heating elements and inlet valves.
This is why some “dishwasher not cleaning” calls in LA aren’t dishwasher failures at all: hard-water buildup has gradually degraded performance to the point of noticing.
Five common causes
| Cause | DIY-fixable? |
|---|---|
| Spray arm holes clogged with scale (hard water) | Mostly yes |
| Heating element scaled or failed | No (technical replacement) |
| Wrong detergent / empty rinse aid | Yes |
| Wash pump failure | No |
| Loading errors / filter clogged | Yes |
Three of the five are things you can check yourself. Worth trying before calling a technician.
DIY checks before calling us
1. Clean the spray arms
Remove the spray arms (upper, lower, and middle if your unit has one) per your owner’s manual. Look at the spray holes — are they showing white mineral deposits? Some completely closed?
Soak the arms in white vinegar for 30 minutes. Use a toothpick or small wire to clear individual holes. Reinstall and run a cycle. When blocked holes were the problem, this alone restores cleaning.
2. Check rinse aid
Many modern dishwashers rely on rinse aid for drying and for spot-free results in hard water. The rinse aid dispenser is typically on the inside of the door near the detergent dispenser. Refill if empty.
3. Verify detergent type
Bosch recommends tablets or powder and says liquid detergents often decrease cleaning performance, especially on tea and coffee stains. In hard water, it also says all-in-one tablets soften water and remove spots better than basic tablets. Never put hand dish soap in a dishwasher.
4. Run a vinegar descale cycle
Place a cup of white vinegar (upright) in the upper rack. Run an empty hot-water cycle. Vinegar dissolves scale throughout the dishwasher interior, including the heating element and water passages.
5. Clean the filter
Most modern dishwashers have a removable filter assembly at the bottom of the tub. Remove per owner’s manual. Rinse under running water. Reinstall. Some dishwashers (older Whirlpool, basic GE) have “self-cleaning” filters which actually just push debris back into the spray water — manual cleaning helps anyway.
When to call a professional
If DIY checks don’t restore cleaning quality, the issue is internal:
- Heating element failure or severe scale insulation: replacement runs $280-$420. Symptom: dishes come out wet, no detergent residue visible (the detergent didn’t dissolve because water didn’t heat).
- Wash pump or motor failure: replacement runs $320-$520. Symptom: cycle runs but minimal water spray sound.
- Water inlet valve restricted: replacement runs $200-$320. Symptom: dishwasher fills slowly or partially.
Dishwasher salt: Miele and some Bosch models
Some dishwashers have a built-in water softener that uses dishwasher salt. Miele’s US operating instructions (for example the G 6980) include a salt reservoir to refill when the display asks for salt, and Bosch says some of its dishwasher models use salt; in hard-water areas it calls salt essential for spot-free glasses and long-term reliability. Not every model has a softener, so check your owner’s manual. If yours has a salt reservoir, fill it with coarse dishwasher salt, never table salt: both makers warn against other salts. We service these on our Bosch repair and dishwasher repair pages.
Annual professional service makes sense in LA
Given LA’s hard water, we recommend annual professional dishwasher service for premium units:
- Spray arm inspection and cleaning
- Filter inspection and replacement if needed
- Softener salt check, on models that have one
- Heating element scale inspection
- Door seal inspection
$120-$180 annually. Compared to a $400 heating element replacement caused by scale damage, the math is straightforward.
Seeing a dishwasher error code?
If your dishwasher is displaying a fault code (E15, E24, i10, F8, etc.), look it up in our Dishwasher Error Code Database for brand-specific meaning and fix steps.
Call (213) 205-2055
Or text a photo of your dishwasher with the model-number visible (typically inside the door panel).
FAQ
Why isn't my dishwasher cleaning dishes properly?
Five common causes in LA: (1) Clogged spray-arm holes from hard-water mineral buildup. LADWP's 2022 area averages run from about 147 to 279 mg/L of hardness, which LADWP itself classes as hard. Scale clogs the spray-arm holes, reducing cleaning power. (2) Heating element failure or scale-coated element — cold water doesn't dissolve detergent properly. (3) Wash pump or motor failing. (4) Wrong detergent type or empty rinse-aid dispenser. (5) Loading errors blocking spray-arm rotation.
How does LA hard water affect dishwashers?
Over time, through scale. LADWP's 2022 figures average 8.6 grains per gallon (147 mg/L) in the San Fernando Valley and Western LA, 9.8 (168 mg/L) in Silver Lake, Downtown and South LA, and 16.3 (279 mg/L) in Eastern LA and the Harbor; LADWP calls anything above 7 grains per gallon hard. Cities with their own water utility, such as Santa Monica and Beverly Hills, publish their own figures. The effects: (1) Spray-arm holes clog with mineral deposits over years, reducing water spray. (2) Heating elements develop scale insulation that reduces heat transfer. (3) Water inlet valves slow due to mineral buildup. (4) Detergent doesn't dissolve as effectively in hard water.
How can I fix a dishwasher not cleaning dishes myself?
Try these in order: (1) Inspect and clean the spray arms — remove them per your owner's manual, soak in white vinegar for 30 minutes, use a toothpick to clear individual spray holes. (2) Refill the rinse-aid dispenser. (3) Use dishwasher detergent, tablets or powder: Bosch says liquid detergents often clean less well. (4) Run an empty cycle with white vinegar in the upper rack to dissolve scale. (5) Clean the dishwasher filter (typically removable from the bottom of the tub). If these don't help, professional service is needed.
Does dishwasher detergent type matter?
Yes. Bosch recommends tablets or powder and says liquid detergents often decrease cleaning performance, especially on tea and coffee stains. In hard water, Bosch also says all-in-one tablets soften water and remove spots better than basic tablets. Never use hand dish soap: Bosch warns it is too foamy and can damage the appliance. Check your own manual for what your model needs, and keep the rinse-aid dispenser filled to cut spotting.
How much does dishwasher repair cost in Los Angeles?
Most repairs for not-cleaning issues run $180–$520. Heating element replacement (most common when scale damages it) $280–$420. Wash pump motor $320–$520. Drain pump $220–$340. Spray arm replacement $180–$280. Filter assembly $150–$240. Our $85 service call is credited toward the completed repair. We also offer descaling service ($120-$180) which can resolve scale-related issues without parts replacement.
How often should I clean my dishwasher?
Filter cleaning: every 1-2 months. Spray-arm inspection: every 2-3 months. Full vinegar descale cycle: every 3-6 months. Annual professional inspection: yearly. LA's hard water makes regular maintenance worthwhile.
Should I get a water softener for my dishwasher?
A whole-home softener reduces scale in every water-using appliance, but LADWP says even its hardest water does not need softening to be safe or usable, so it is a cost decision: get a plumber's quote. For the dishwasher alone, rinse aid and a periodic descaling product are the inexpensive options. Some dishwashers have a built-in softener with a salt reservoir; Miele's US manuals call for dishwasher salt, and Bosch says some of its models use it. If yours has one, fill it with coarse dishwasher salt as the manual says, never table salt.
Got an appliance that needs fixing? We cover LA and the Valley.
Call (213) 205-2055 or text a photo of your appliance.