If the standing water was there immediately after the new dishwasher was ran the first time I would suspect a restriction in the discharge hose or a clog just past where it connects to the plumbing system. Start by checking the discharge hose for kinks. If there are no kinks provide more information about how it is connected and how it is routed so I can offer more suggestions.
If it develop over a few days or weeks after the install I suspect something is getting into the dishwasher and clogging the screen where the water drains. Remove the lower rack (it should just lift out) and check around the bottom center for junk that my be clogging the screen or grate.
Rege
If it develop over a few days or weeks after the install I suspect something is getting into the dishwasher and clogging the screen where the water drains. Remove the lower rack (it should just lift out) and check around the bottom center for junk that my be clogging the screen or grate.
Rege