A dishwasher speaks of holiness and righteousness. It speaks of being cleansed (It is the opposite of the Scripture that says that people who do bad things will not see God). Sin removes our ability and the privilege to see God. To see God is to be with God. If you are in God’s presence, you have a personal relationship with him.
To be kept cleansed and holy plays a part in this. The fact that the plastic container is placed diagonally and with the opening facing down, speaks of an important position. We are earthly vessels that are supposed to be full of God (standing upright and filled with the Holy Spirit and Jesus in us and the Father in us), but when it comes to cleansing and holiness (dishwasher) our position must be diagonal and the opening must be at the bottom so that all sin and dirt and things that make us unholy can be removed (flows out). We need to be pure and clean vessels.
People cannot know God intimately when they are doing wrong things. Even the small little sins that Christians harbor in their hearts separate them from God. This is why God is so strict when it comes to the pursuit of holiness. Sin takes away our confidence in Christ. It replaces it with guilt and doubt and that removes us from the presence of God. Adam and Eve decided to hide away from God immediately after they committed sin. This is still true, even in the lives of Christians.
This dream is a confirmation that when people want to know God intimately, they need to pursue holiness.
Yet, the symbols in this dream are not about baths or showers or soap or the washing of the body or face or hands and feet, although this is also true for those symbols, this specific dream is about doctrines and belief systems and the ability to accommodate the right doctrines. This dream is about the washing of cutlery and equipment that we use in kitchens to provide people with food and drinks. This is what dishwashers are for. It speaks of us being pure vessels with the ability to contain the pure word of God and the ability to grasp and accept His will and His ways.
This speaks of the fact that false teachings and wrong perceptions of God and his word and his will also lead to separation. It speaks of the fact that what we know and believe, contaminates our ability to know God or negatively influences our ability to know God intimately. We cannot know God intimately if we believe wrong things about him and his ways and his will.
I believe that the large plastic container symbolizes you (or your heart for your heart (tables of your heart) is where the word of God or beliefs about God and his word and his ways are kept). It speaks of you allowing yourself to be cleansed of wrong teachings and wrong ideas about God and his word and his will so that your relationship with him can improve and so that you can learn to know him more intimately.