How to Fix a Dishwasher That Will Not Drain. Part of the series: Home Improvements & Maintenance. To fix a dishwasher that will not drain, remove any clogs that are blocking the drain line by pouring a paste of baking soda, vinegar and water down the drain, and then pouring boiling water to clear the clog. Repeat the process several times to remove a severely clogged dishwasher drain with help from a remodeling contractor and home repair specialist in this free video on appliance repair.