Dish washer

Low water in all filling modes. Have to add water during all fillings.
How do I adjust or repair?

I cannot find any info on the given model number please check it.

The most common cause is a dirty screen filter on the input side of the fill calve. Remove the valve from the unit and clean/check the filter.
Do not permanently remove it from the valve as it is there to keep crud out of the valve which could hold it open and cause a flood.

If it still does not fill correctly I would replace the fill valve.

PS: Be sure to shut off the power and the water supply to the unit. Have paper towels etc. handy to wipe up any spilled water. Get a small pan/bowl etc. that will fit under the valve then loosen the input water line let it drip into the container emptying it as necessary. This will minimize the amount of water spilled.

My wife said our unit is about 12 to 15 years old. Maybe thats; why you could not find Model No. It is DU8700XY-1. Serial No. is FB2432446.
I will pull the intake valve & check it out. Do you think it may be the float or float switch?

Here are your parts
Replacement parts for WHIRLPOOL DU8700XY1 DISHWASHERS | AppliancePartsPros.com

[COLOR=“DarkRed”]Do you think it may be the float or float switch?[/COLOR]
No, as you are getting water just not enough.