DishwashersStandard
LG LDT780#** Dishwasher Manual
Setup, everyday use, maintenance and troubleshooting for the 24 in. stainless-tub dishwasher, with verified specifications.
- Capacity15 place settings
- Width23.7 in.
- Water use2.9 gal/cycle
- Est. yearly cost$49.81
About the LG LDT780#**
Model LDT780#** from LG is a 24 in. stainless-tub dishwasher that meets ENERGY STAR efficiency requirements. It is rated for 15 place settings and measures 23.7 in. wide and 24.6 in. deep.
Listed equipment includes a stainless steel tub, a soil sensor that adjusts the cycle to how dirty the dishes are, a third rack for utensils and flat items, and hidden top-edge controls. Its listed drying method is fan-assisted drying.
Rated energy use is 238 kWh per year (22% below the federal limit), and each normal cycle uses 2.9 gallons of water (42% below the limit). That is better than 61% of the 617 standard dishwashers in our database.
Specifications
| Brand | LG |
|---|---|
| Model number | LDT780#** |
| Size class | Standard |
| Capacity | 15 place settings |
| Width | 23.7 in. |
| Depth | 24.6 in. |
| Tub material | Stainless Steel |
| Drying method | Fan-Assisted Dry |
| Soil sensor | Yes |
| Control placement | Top (hidden) |
| Third rack | Yes |
| Listed features | Top Controls, Third Rack |
| Annual energy use | 238 kWh/yr |
| U.S. federal standard (energy) | 307 kWh/yr |
| Energy savings vs. federal standard | 22% |
| Water use | 2.90 gal/cycle |
| U.S. federal standard (water) | 5.0 gal/cycle |
| Water savings vs. federal standard | 42% |
| Smart / connected features | No |
| ENERGY STAR Most Efficient | No |
Safety information
- Connect the dishwasher to a properly grounded 120 V circuit as specified in the installation instructions — hard-wired or through a grounded outlet, depending on the model and local code.
- Do not sit, stand or lean on the open door or racks; the door can bend or the cabinet can tip forward.
- Load sharp knives and utensils with the points down, or lay them flat in a utensil tray or third rack.
- Keep detergent pods and packets out of children's reach and close the dispenser right after filling; detergent is a poisoning and eye-injury hazard.
- Steam and very hot water can escape when the door is opened mid-cycle or at the end of a heated cycle. Open the door slowly and let dishes cool before unloading.
- Use only detergent made for automatic dishwashers. Hand dishwashing liquid creates excess suds that can overflow onto the floor.
- Wash only items marked dishwasher-safe; thin plastics can melt near a heating element.
Installation and first-time setup
This model is 23.7 in. wide, sized for a standard 24 in. cabinet opening. Rated depth is 24.6 in.; confirm that the opening is deep enough for the unit plus the water, drain and electrical connections behind it. Height is not published in the certification data, so measure the opening from floor to the underside of the countertop and compare it with the manufacturer's specification sheet.
- Shut off utilities
Turn off the circuit breaker and the hot-water supply before removing an old dishwasher or making connections.
- Connect the water supply
Connect the inlet valve to the hot-water line with a new 3/8 in. compression supply line (braided stainless is the most durable choice). Water pressure should fall within the range listed in the installation instructions — commonly 20–120 psi.
- Connect the drain
Route the drain hose to the sink drain or disposer with a high loop up under the countertop or through an air gap, as local plumbing code requires. If you connect to a new garbage disposer, knock out the plug inside its dishwasher inlet first — a forgotten knockout is the most common reason a new dishwasher will not drain.
- Make the electrical connection
Hard-wire the unit in its junction box or use the manufacturer's power-cord kit, following local code. Most dishwashers call for a dedicated 15 A or 20 A, 120 V circuit; use the rating on the installation instructions.
- Level and secure
Adjust the legs until the dishwasher is level front to back and side to side and the door opens and closes without rubbing, then fasten the mounting brackets to the countertop or side cabinets so the unit cannot tip forward.
- Test for leaks
Restore water and power and run a short cycle while watching every connection. Check again after the first full cycle.
Using your dishwasher
Loading for best results
The 15-place-setting rating is a standardized test measure; real capacity depends on the size and shape of your dishes. Scrape off food scraps, but skip pre-rinsing — this model's soil sensor reads how dirty the water is and may choose a lighter wash if dishes go in already clean.
- Lower rack: plates, pans and serving bowls facing the center spray arm, with the dirtiest surfaces facing the spray.
- Upper rack: glasses, cups, small bowls and dishwasher-safe plastics, angled so water drains off.
- Mix forks and spoons handle-down in the basket so they do not nest; knives point-down.
- Make sure nothing blocks the spray arms from turning or covers the detergent dispenser door.
- Use the third rack for spatulas, serving utensils, lids and other flat items to free up space in the lower racks.
Detergent and rinse aid
Use automatic-dishwasher detergent — pods, powder or gel — in the amount recommended for your water hardness; too much detergent in soft water can etch glassware. Keep the rinse-aid dispenser topped up, especially if the dishwasher does not use a heating element to dry.
Choosing a cycle
The Normal (or Auto/Eco) cycle is the one used for the certified energy rating of 238 kWh per year. Efficient dishwashers save energy by washing longer at lower temperatures, so cycles of two to three hours or more are normal. Run the kitchen tap until the water is hot before starting, and save Heavy, Sanitize or high-temperature options for loads that need them.
Drying
- Fan-assisted drying circulates air through the tub to carry moisture out.
- Whatever the method, rinse aid makes the biggest difference, and unloading the bottom rack first keeps drips from cups and bowls off dry dishes.
Care and maintenance
| When | What to do |
|---|---|
| Every month (or weekly with heavy use) | Remove and rinse the filter assembly under warm running water; scrub the fine mesh with a soft brush. |
| Every month | Wipe the door gasket, the door edges and the bottom of the door (outside the tub) where splashes collect. Run an empty hot cycle with a dishwasher cleaner approved by the manufacturer. |
| Every 3 months | Check the spray arms for clogged holes; clear them with a toothpick and rinse. Make sure the arms spin freely. |
| As needed | Refill rinse aid when the indicator shows or the dispenser looks low. Clean the air gap cap on the sink, if fitted. |
| Before a long absence | Leave the door slightly open to prevent odors. In an unheated home at risk of freezing, have the water line and pump drained. |
Troubleshooting
Most dishwasher problems come down to loading, the filter or the water supply. Work through the checks below before calling for service; if the display shows a code, look it up in the code table in your manufacturer's manual.
| Problem | Possible cause | What to try |
|---|---|---|
| Dishes not getting clean | Clogged filter; blocked spray arm; overcrowded racks; water not hot at the start; too little detergent. | Clean the filter and spray arms; reload with space between items; run the tap hot before starting; adjust detergent for your water hardness. |
| Cloudy or spotted glasses | Hard-water minerals; empty rinse-aid dispenser; etching from too much detergent in soft water. | Refill rinse aid; use a detergent with a hard-water booster. Film that will not wipe off with vinegar is permanent etching — cut back on detergent. |
| Dishes still wet at the end | Normal for plastics; no rinse aid; dishes unloaded too soon. | Use rinse aid, select the strongest drying option offered, and wait 15–30 minutes after the cycle before unloading. |
| Water left in the bottom | Clogged filter; kinked drain hose; blocked air gap or disposer inlet; cycle interrupted. | Clean the filter, straighten the hose, clear the air gap, and run the disposer before starting the dishwasher. |
| Leaking onto the floor | Wrong detergent causing suds; unit not level; damaged door gasket; loose supply or drain fitting. | Use only dishwasher detergent; re-level; inspect the gasket; tighten fittings with the power and water off. |
| Dishwasher will not start | Door not latched; control lock or delay start active; tripped breaker; supply valve closed. | Close the door firmly, cancel the lock or delay, check the breaker and make sure the water valve is open. |
| Bad odor | Food trapped in the filter or around the gasket; door kept closed between uses. | Clean the filter and gasket, run a hot cleaning cycle, and leave the door ajar after use. |
| Cycle seems very long | Normal for energy-efficient cycles; cold incoming water; sensor adding time for heavy soil. | Long Normal or Eco cycles are expected. Running the tap hot before starting can shorten heat-up time. |
Energy use and running costs
The LG LDT780#** is rated at 238 kWh per year under the U.S. Department of Energy test procedure, which assumes 215 cycles a year and includes the energy to heat the wash water with an electric water heater. At $0.17 per kWh, that is about $40.46 per year.
At 2.9 gallons per cycle, the same 215 cycles use about 624 gallons of water a year — roughly $9.35 at $0.015 per gallon for water and sewer. Combined running cost: about $49.81 per year.
The federal limits for this size class are 307 kWh/yr and 5 gallons per cycle. Compared with a model at the limit, this one saves about 69 kWh ($11.73) a year and 452 gallons of water. Its water use per cycle is lower than 82% of comparable models in our database.
If your home has a gas water heater, your electricity cost will be lower than shown and part of the cost shifts to gas. Running full loads and skipping heated dry and high-temperature options are the easiest ways to cut costs further.
Frequently asked questions
How many place settings does the LG LDT780#** hold?
It is rated for 15 place settings. Real capacity depends on the size and shape of your dishes and cookware.
What are the dimensions of the LG LDT780#**?
The certification data lists a width of 23.7 in. and a depth of 24.6 in. Height is not published there, so confirm it with the manufacturer's specification sheet before ordering.
How much does it cost to run the LG LDT780#**?
It is rated at 238 kWh per year and 2.9 gallons per cycle. At $0.17/kWh and $0.015/gallon, that is about $49.81 a year over 215 cycles.
How does the LG LDT780#** dry dishes?
The certification record lists fan-assisted drying as its drying method. Keep the rinse-aid dispenser filled for the best results.
What is the tub made of on the LG LDT780#**?
It has a stainless steel tub, which resists staining and odors and holds heat well for drying.
Does the LG LDT780#** have a third rack?
Yes. A third rack is listed among its features — use it for utensils, spatulas and other flat items.
Is the LG LDT780#** ENERGY STAR certified?
Yes. It appears on the ENERGY STAR certified dishwashers list, with a certification date of June 2023.
Sources and disclaimer
Specifications on this page come from the ENERGY STAR certified dishwashers dataset published by the U.S. Environmental Protection Agency (record certified June 20, 2023), retrieved October 7, 2026.
The setup, operating, maintenance and troubleshooting guidance is written by ManualHarbor's editors for this specific product type and configuration. It is an independent guide — not a reproduction of the manufacturer's manual — and ManualHarbor is not affiliated with LG. Always follow the safety instructions, installation requirements and warranty terms supplied with your unit, and contact LG or an authorized service provider for warranty repairs and replacement parts.
Running-cost figures use assumed U.S. average utility prices and are estimates for comparison only. See our editorial methodology for details.
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